U.S. patent application number 11/395159 was filed with the patent office on 2007-01-04 for light-emitting device with built-in microlens and method of forming the same.
This patent application is currently assigned to SANYO ELECTRIC CO., LTD.. Invention is credited to Masayuki Shono, Keiji Tanaka.
Application Number | 20070001184 11/395159 |
Document ID | / |
Family ID | 31492396 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070001184 |
Kind Code |
A1 |
Tanaka; Keiji ; et
al. |
January 4, 2007 |
Light-emitting device with built-in microlens and method of forming
the same
Abstract
A light-emitting device with a built-in microlens having a
microlens integrated with a semiconductor light-emitting device
causing no misalignment of an optical axis is provided. This
light-emitting device with a built-in microlens comprises a
semiconductor light-emitting device and a microlens, integrated
with the semiconductor light-emitting device, formed through light
emitted from the semiconductor light-emitting device. Thus, the
optical axis of the microlens is automatically aligned in formation
of the microlens.
Inventors: |
Tanaka; Keiji; (Sapporo-shi,
JP) ; Shono; Masayuki; (Osaka, JP) |
Correspondence
Address: |
McDermott Will & Emery LLP
600 13th Street, N.W.
Washington
DC
20005-3096
US
|
Assignee: |
SANYO ELECTRIC CO., LTD.
Osaka
JP
|
Family ID: |
31492396 |
Appl. No.: |
11/395159 |
Filed: |
April 3, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10636736 |
Aug 8, 2003 |
7038247 |
|
|
11395159 |
Apr 3, 2006 |
|
|
|
Current U.S.
Class: |
257/98 ;
257/E33.068; 257/E33.073; 438/27 |
Current CPC
Class: |
H01S 5/4087 20130101;
G02B 6/4203 20130101; G02B 6/4206 20130101; H01S 5/0267 20130101;
H01L 33/58 20130101; H01L 33/44 20130101; H01S 5/4025 20130101 |
Class at
Publication: |
257/098 ;
438/027; 257/E33.073 |
International
Class: |
H01L 33/00 20060101
H01L033/00; H01L 21/00 20060101 H01L021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 9, 2002 |
JP |
JP2002-232374 |
Claims
1-14. (canceled)
15. A method of forming a light-emitting device with a built-in
microlens, comprising steps of: forming a photosensitive material
on an emission surface of a semiconductor light-emitting device;
and forming a microlens integrated with said semiconductor
light-emitting device by irradiating said photosensitive material
with light emitted from said semiconductor light-emitting device
thereby reacting said photosensitive material.
16. The method of forming a light-emitting device with a built-in
microlens according to claim 15, wherein said step of forming said
microlens includes a step of forming such a graded index microlens
that the refractive index of a photo-irradiated portion of said
photosensitive material is larger than the refractive index of the
remaining unirradiated portion of said photosensitive material.
17. The method of forming a light-emitting device with a built-in
microlens according to claim 15, wherein said step of forming said
microlens includes a step of forming a convex microlens by
irradiating said photosensitive material with said light emitted
from said semiconductor light-emitting device and thereafter
etching a prescribed region of said photosensitive material.
18. The method of forming a light-emitting device with a built-in
microlens according to claim 15, wherein said step of forming said
microlens includes a step of forming a concave microlens by
irradiating said photosensitive material with said light emitted
from said semiconductor light-emitting device thereby evaporating
said photosensitive material.
19. The method of forming a light-emitting device with a built-in
microlens according to claim 15, further comprising a step of
performing heat treatment at a temperature around the glass
transition temperature of said photosensitive material before
irradiating said photosensitive material with said light emitted
from said semiconductor light-emitting device, wherein said step of
forming said microlens includes a step of forming a graded index
microlens having a convex shape by irradiating said photosensitive
material with said light emitted from said semiconductor
light-emitting device after said step of performing heat
treatment.
20. The method of forming a light-emitting device with a built-in
microlens according to claim 15, further comprising a step of
forming a transparent insulating spacer on said emission surface of
said semiconductor light-emitting device before forming said
photosensitive material on said emission surface of said
semiconductor light-emitting device.
21. The method of forming a light-emitting device with a built-in
microlens according to claim 15, further comprising steps of:
forming a first antireflection coating on said emission surface of
said semiconductor light-emitting device before forming said
photosensitive material on said emission surface of said
semiconductor light-emitting device, and forming a second
antireflection coating on the surface of said photosensitive
material after forming said photosensitive material on said
emission surface of said semiconductor light-emitting device.
22. The method of forming a light-emitting device with a built-in
microlens according to claim 15, wherein said microlens consists of
a photosensitive material of either chalcogenide glass or
photoreactive organic matter.
23. A method of forming a light-emitting device with a built-in
microlens, comprising steps of: arranging a photosensitive material
in the vicinity of an emission surface of a semiconductor
light-emitting device; and forming a convex microlens integrated
with said semiconductor light-emitting device by irradiating said
photosensitive material with light emitted from said semiconductor
light-emitting device thereby evaporating said photosensitive
material.
24. The method of forming a light-emitting device with a built-in
microlens according to claim 23, wherein said microlens consists of
a photosensitive material of either chalcogenide glass or
photoreactive organic matter.
25. The method of forming a light-emitting device with a built-in
microlens according to claim 15, wherein said step of forming said
microlens includes a step of forming said microlens for each of a
plurality of emission parts of said semiconductor light-emitting
device having said plurality of emission parts.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a light-emitting device
with a built-in microlens and a method of forming the same, and
more specifically, it relates to a light-emitting device with a
built-in microlens having a microlens integrated with a
semiconductor light-emitting device and a method of forming the
same.
[0003] 2. Description of the Background Art
[0004] In general, a microlens having an aperture of about several
10 .mu.m is known as an optical lens employed for an optical
communication system. This microlens is employed in an optical
communication system having a transmission medium of optical fiber
for efficiently interconnecting optical components such as a
semiconductor laser and an optical fiber member with each
other.
[0005] When such a microlens is assembled with a light-emitting
device such as a semiconductor laser, a microlens group
manufactured independently of the light-emitting device is
generally combined with the light-emitting device thereby obtaining
necessary optical properties. When the light-emitting device and
the microlens group are manufactured independently of each other,
however, the light-emitting device is disadvantageously hard to
miniaturize. Further, such combination of the microlens group and
the light-emitting device inconveniently requires an optical axis
adjusting step with precision of about 1 micron.
[0006] Therefore, Japanese Patent Laying-Open No. 2001-28456 or the
like generally proposes a technique of forming a microlens
integrated with a semiconductor light-emitting device. According to
the technique proposed in this gazette, a cladding layer and a
contact layer of the semiconductor light-emitting device are
partially worked by lithography and etching thereby forming a
Fresnel lens pattern (microlens). Thus, a Fresnel lens part
(microlens) integrated with the semiconductor light-emitting device
is so formed as to require no optical axis adjusting step and
enable miniaturization.
[0007] In the structure proposed in the aforementioned gazette,
however, the microlens is formed by partially working the cladding
layer and the contact layer of the semiconductor light-emitting
device by lithography and etching, and hence patterning
misregistration may be caused in lithography. Such patterning
misregistration may disadvantageously result misalignment of an
optical axis.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to provide a
light-emitting device with a built-in microlens having a microlens
integrated with a light-emitting device causing no misalignment of
an optical axis.
[0009] In order to attain the aforementioned object, a
light-emitting device with a built-in microlens according to a
first aspect of the present invention comprises a semiconductor
light-emitting device and a microlens, integrated with the
semiconductor light-emitting device, formed through light emitted
from the semiconductor light-emitting device.
[0010] The light-emitting device with a built-in microlens
according to the first aspect is provided with the microlens formed
through the light emitted from the semiconductor light-emitting
device as hereinabove described, whereby the optical axis of the
microlens is automatically aligned in formation of the microlens so
that the optical axis is not misaligned by patterning
misregistration dissimilarly to a microlens formed by lithography
and etching. Further, the microlens is so integrally provided with
the semiconductor light-emitting device that an emission source can
be miniaturized.
[0011] In the aforementioned light-emitting device with a built-in
microlens according to the first aspect, the microlens preferably
consists of a photosensitive material of either chalcogenide glass
or photoreactive organic matter. According to this structure, the
microlens can be easily formed by irradiating the aforementioned
photosensitive material with the light emitted from the
semiconductor light-emitting device.
[0012] In the aforementioned case, the chalcogenide glass may
include an As.sub.2S.sub.3 film.
[0013] In the aforementioned case, the microlens may include a
microlens having either a convex shape or a concave shape, or a
graded index microlens.
[0014] In the aforementioned case, the microlens may be formed as a
graded index microlens having a convex part.
[0015] In the aforementioned light-emitting device with a built-in
microlens according to the first aspect, the microlens preferably
has a function of substantially circularizing an elliptic emission
spot from the semiconductor light-emitting device. According to
this structure, light can be easily introduced into a cylindrical
optical system such as an optical fiber member with the microlens
in the semiconductor light-emitting device such as an edge emission
laser having an elliptic emission spot.
[0016] In the aforementioned light-emitting device with a built-in
microlens according to the first aspect, the semiconductor
light-emitting device may have a plurality of emission parts, and
the microlens may be formed for each of the plurality of emission
parts.
[0017] The aforementioned light-emitting device with a built-in
microlens according to the first aspect preferably further
comprises a transparent insulating spacer provided between an
emission surface of the semiconductor light-emitting device and the
microlens. According to this structure, the distance between the
emission surface of the semiconductor light-emitting device and the
microlens can be varied by adjusting the thickness of the spacer,
thereby varying imaging characteristics of the microlens. In this
case, the spacer may include a GeO.sub.2 film.
[0018] The aforementioned light-emitting device with a built-in
microlens according to the first aspect preferably further
comprises a first antireflection coating provided between an
emission surface of the semiconductor light-emitting device and the
microlens and a second antireflection coating provided on the
surface of the microlens. According to this structure, the first
and second antireflection coatings can prevent multiple reflection,
whereby the characteristics of the microlens can be improved. In
this case, the first antireflection coating and the second
antireflection coating may include CdSe films.
[0019] In the aforementioned light-emitting device with a built-in
microlens according to the first aspect, the microlens preferably
includes a photo-irradiated part irradiated with the light emitted
from the semiconductor light-emitting device, and the
photo-irradiated part of the microlens preferably has a larger
refractive index than the remaining part of the microlens.
According to this structure, a graded index microlens having a
photo-irradiated part exhibiting a larger refractive index than
that of unirradiated part can be easily formed.
[0020] In the aforementioned light-emitting device according to the
first aspect, the semiconductor light-emitting device preferably
includes an edge emission semiconductor laser. According to this
structure, an edge emission semiconductor laser with a built-in
microlens inhibited from misalignment of an optical axis can be
easily obtained.
[0021] A method of forming a light-emitting device with a built-in
microlens according to a second aspect of the present invention
comprises steps of forming a photosensitive material on an emission
surface of a semiconductor light-emitting device and forming a
microlens integrated with the semiconductor light-emitting device
by irradiating the photosensitive material with light emitted from
the semiconductor light-emitting device thereby reacting the
photosensitive material.
[0022] In the method of forming a light-emitting device with a
built-in microlens according to the second aspect, the microlens
integrated with the semiconductor light-emitting device can be
easily formed by forming the photosensitive material on the
emission surface of the semiconductor light-emitting device and
thereafter irradiating the photosensitive material with the light
emitted from the semiconductor light-emitting device thereby
reacting the photo-irradiated part of the photosensitive material.
Consequently, an emission source can be miniaturized. The microlens
is so formed through the light emitted from the semiconductor
light-emitting device mounted with the microlens that the optical
axis of the microlens is automatically aligned in formation of the
microlens, whereby the optical axis is not misaligned by patterning
misregistration dissimilarly to a microlens formed by lithography
and etching.
[0023] In the aforementioned method of forming a light-emitting
device with a built-in microlens according to the second aspect,
the step of forming the microlens preferably includes a step of
forming such a graded index microlens that the refractive index of
a photo-irradiated portion of the photosensitive material is larger
than the refractive index of the remaining unirradiated portion of
the photosensitive material. According to this structure, the
graded index microlens can be easily formed so that the
photo-irradiated portion of the photosensitive material has a
larger refractive index than that of unirradiated portion.
[0024] In the aforementioned method of forming a light-emitting
device with a built-in microlens according to the second aspect,
the step of forming the microlens preferably includes a step of
forming a convex microlens by irradiating the photosensitive
material with the light emitted from the semiconductor
light-emitting device and thereafter etching a prescribed region of
the photosensitive material. According to this structure, the
portion irradiated with the light emitted from the semiconductor
light-emitting device is hardly etched in response to the exposure,
whereby an unirradiated portion and part of the irradiated portion
of the photosensitive material are easily selectively etched. Thus,
the convex microlens can be easily formed.
[0025] In the aforementioned method of forming a light-emitting
device with a built-in microlens according to the second aspect,
the step of forming the microlens preferably includes a step of
forming a concave microlens by irradiating the photosensitive
material with the light emitted from the semiconductor
light-emitting device thereby evaporating the photosensitive
material. According to this structure, the concave microlens
consisting of the photosensitive material having a concavely
evaporated portion can be easily formed.
[0026] The aforementioned method of forming a light-emitting device
with a built-in microlens according to the second aspect preferably
further comprises a step of performing heat treatment at a
temperature around the glass transition temperature of the
photosensitive material before irradiating the photosensitive
material with the light emitted from the semiconductor
light-emitting device, and the step of forming the microlens
preferably includes a step of forming a graded index microlens
having a convex shape by irradiating the photosensitive material
with the light emitted from the semiconductor light-emitting device
after the step of performing heat treatment. The heat treatment and
photoirradiation are so performed that the refractive index of the
portion of the photosensitive material irradiated with the light
emitted from the semiconductor light-emitting device is increased
while the volume is also simultaneously increased due to
photoinduced volume expansion when this portion is irradiated with
the light emitted from the semiconductor light-emitting device,
whereby a protuberance is formed on the irradiated surface of the
photosensitive material. Thus, the graded index microlens having a
convex shape consisting of the photosensitive material having the
protuberance on the irradiated surface can be easily formed.
[0027] The aforementioned method of forming a light-emitting device
with a built-in microlens according to the second aspect preferably
further comprises a step of forming a transparent insulating spacer
on the emission surface of the semiconductor light-emitting device
before forming the photosensitive material on the emission surface
of the semiconductor light-emitting device. According to this
structure, the distance between the emission surface of the
semiconductor light-emitting device and the microlens can be varied
by adjusting the thickness of the spacer, thereby varying imaging
characteristics of the microlens.
[0028] The aforementioned method of forming a light-emitting device
with a built-in microlens according to the second aspect preferably
further comprises steps of forming a first antireflection coating
on the emission surface of the semiconductor light-emitting device
before forming the photosensitive material on the emission surface
of the semiconductor light-emitting device and forming a second
antireflection coating on the surface of the photosensitive
material after forming the photosensitive material on the emission
surface of the semiconductor light-emitting device. According to
this structure, multiple reflection can be so prevented that the
characteristics of the microlens can be improved.
[0029] In the aforementioned method of forming a light-emitting
device with a built-in microlens according to the second aspect,
the microlens preferably consists of a photosensitive material of
either chalcogenide glass or photoreactive organic matter.
According to this structure, the microlens can be easily formed by
irradiating the aforementioned photosensitive material with the
light emitted from the semiconductor light-emitting device.
[0030] A method of forming a light-emitting device with a built-in
microlens according to a third aspect of the present invention
comprises steps of arranging a photosensitive material in the
vicinity of an emission surface of a semiconductor light-emitting
device and forming a convex microlens integrated with the
semiconductor light-emitting device by irradiating the
photosensitive material with light emitted from the semiconductor
light-emitting device thereby partially evaporating the
photosensitive material.
[0031] In the method of forming a light-emitting device with a
built-in microlens according to the third aspect, the microlens
integrated with the semiconductor light-emitting device can be
easily formed by arranging the photosensitive material in the
vicinity of the emission surface of the semiconductor
light-emitting device and thereafter irradiating the photosensitive
material with the light emitted from the semiconductor
light-emitting device thereby evaporating the photosensitive
material. Consequently, an emission source can be miniaturized.
Further, the microlens is so formed through the light emitted from
the semiconductor light-emitting device mounted with the microlens
that the optical axis of the microlens is automatically aligned in
formation of the microlens, whereby the optical axis is not
misaligned by patterning misregistration dissimilarly to a
microlens formed by lithography and etching.
[0032] In the aforementioned method of forming a light-emitting
device with a built-in microlens according to the third aspect, the
microlens preferably consists of a photosensitive material of
either chalcogenide glass or photoreactive organic matter.
According to this structure, the microlens can be easily formed by
irradiating the aforementioned photosensitive material with the
light emitted from the semiconductor light-emitting device.
[0033] In the aforementioned method of forming a light-emitting
device with a built-in microlens according to the second aspect,
the step of forming the microlens may include a step of forming the
microlens for each of a plurality of emission parts of the
semiconductor light-emitting device having the plurality of
emission parts.
[0034] The foregoing and other objects, features, aspects and
advantages of the present invention will become more apparent from
the following detailed description of the present invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a sectional view showing the structure of a
light-emitting device with a built-in microlens according to a
first embodiment of the present invention;
[0036] FIGS. 2 to 4 are sectional views for illustrating a process
of forming the light-emitting device with a built-in microlens
according to the first embodiment shown in FIG. 1;
[0037] FIG. 5 is a sectional view of the light-emitting device with
a built-in microlens according to the first embodiment, which is
applied to a light-emitting device having a plurality of emission
parts;
[0038] FIG. 6 is a sectional view showing the structure of a
light-emitting device with a built-in microlens according to a
second embodiment of the present invention;
[0039] FIGS. 7 and 8 are sectional views for illustrating a process
of forming the light-emitting device with a built-in microlens
according to the second embodiment shown in FIG. 6;
[0040] FIG. 9 is a sectional view showing the structure of a
light-emitting device with a built-in microlens according to a
third embodiment of the present invention;
[0041] FIGS. 10 and 11 are sectional views for illustrating a
process of forming the light-emitting device with a built-in
microlens according to the third embodiment shown in FIG. 9;
[0042] FIG. 12 is a sectional view showing the structure of a
light-emitting device with a built-in microlens according to a
fourth embodiment of the present invention;
[0043] FIGS. 13 and 14 are sectional views for illustrating a
process of forming the light-emitting device with a built-in
microlens according to the fourth embodiment shown in FIG. 12;
[0044] FIG. 15 is a sectional view showing the structure of a
light-emitting device with a built-in microlens according to a
fifth embodiment of the present invention;
[0045] FIG. 16 is a sectional view showing the structure of a
light-emitting device with a built-in microlens according to a
sixth embodiment of the present invention; and
[0046] FIG. 17 is a sectional view for illustrating a process of
forming the light-emitting device with a built-in microlens
according to the seventh embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] Embodiments of the present invention are now described with
reference to the drawings.
[0048] (First Embodiment)
[0049] In a light-emitting device with a built-in microlens
according to a first embodiment of the present invention, a graded
index microlens consisting of a chalcogenide glass film 11 is
integrally formed on an emission edge of an edge emission
semiconductor laser 10 having an emission layer 10a as shown in
FIG. 1. The chalcogenide glass film 11 constituting the microlens
consists of an As.sub.2S.sub.3 film having a thickness of about 4
.mu.m and has a photo-irradiated part 12 having a larger refractive
index than that of unirradiated part. The semiconductor laser 10 is
an example of the "semiconductor light-emitting device" in the
present invention, and the chalcogenide glass film 11 is an example
of the "photosensitive material" in the present invention.
[0050] A method of forming the light-emitting device with a
built-in microlens according to the first embodiment is now
described with reference to FIGS. 2 to 4.
[0051] First, the chalcogenide glass film 11 consisting of an
AS.sub.2S.sub.3 film is formed on a side edge of the edge emission
semiconductor laser 10 with the thickness of about 4 .mu.m, as
shown in FIG. 2.
[0052] Thereafter the semiconductor laser 10 is so driven as to
emit a laser beam 100 from the emission layer 10a, as shown in FIG.
3. More specifically, the semiconductor laser 10 irradiates the
chalcogenide glass film 11 with the laser beam 100 of about 660 nm
with power of about 50 mW for about 10 minutes. Thus, the
refractive index of the photo-irradiated part 12 of the
chalcogenide glass film 11 is increased due to photopolymerization
and photoinduced refractive index change.
[0053] When the semiconductor laser 10 continuously irradiates the
chalcogenide glass film 11 with the laser beam 100, the increasing
change of the refractive index of the photo-irradiated part 12 of
the chalcogenide glass film 11 is saturated. Thus, the graded index
microlens consisting of the chalcogenide glass film 11 having the
photo-irradiated part 12 exhibiting a larger refractive index than
that of unirradiated part is formed as shown in FIG. 4.
[0054] According to the first embodiment, as hereinabove described,
the laser beam 100 emitted from the semiconductor laser 10 is
applied to the chalcogenide glass film 11 employed as a
photosensitive material for increasing the refractive index of the
photo-irradiated part 12 of the chalcogenide glass film 11 due to
photopolymerization and photoinduced refractive index change,
whereby the graded index microlens having the photo-irradiated part
12 exhibiting a larger refractive index than that of unirradiated
part can be easily formed.
[0055] According to the first embodiment, further, the microlens
consisting of the chalcogenide glass film 11 is formed through the
laser beam 100 emitted from the semiconductor laser 10 mounted with
the microlens so that the optical axis of the microlens is
automatically aligned in formation of the microlens, whereby the
optical axis is not misaligned by patterning misregistration
dissimilarly to a microlens formed by lithography and etching.
[0056] According to the first embodiment, in addition, the
chalcogenide glass film 11 is formed on the emission edge of the
semiconductor laser 10 by vacuum deposition for thereafter forming
the graded index microlens having the photo-irradiated part 12
exhibiting a larger refractive index than that of unirradiated part
by photoirradiation from the semiconductor laser 10, whereby the
microlens can be easily integrated with the semiconductor laser
10.
[0057] The semiconductor laser 10 may be formed by a multi-beam
semiconductor laser having a plurality of emission parts or a
semiconductor laser array. More specifically, a semiconductor laser
50 having a plurality of emission parts consisting of a plurality
of emission layers 10a may be formed with a microlens consisting of
a chalcogenide glass film 11 having a photo-irradiated part 12
exhibiting a larger refractive index than that of unirradiated part
for each of the plurality of emission parts, as shown in FIG. 5.
Further, the semiconductor laser 10 may also be formed by a
multi-wavelength laser including a plurality of emission parts
having different oscillation wavelengths, or a two-dimensional
laser array employing an edge emission laser or the like. When the
semiconductor laser 10 is formed by a multi-beam semiconductor
laser or a semiconductor laser array, a multi-beam semiconductor
laser or a semiconductor laser array with a built-in microlens can
be easily prepared. In this case, the beam interval of the
semiconductor laser 10 is preferably larger than about 10 .mu.m,
more preferably larger than about 15 .mu.m in order to prevent
influence exerted by an adjacent laser beam on formation of the
microlens. It is also possible to prepare a desired microlens every
beam by varying the photosensitive material and the method of
preparing the microlens with each beam.
[0058] (Second Embodiment)
[0059] Referring to FIG. 6, a chalcogenide glass film 21
constituting a microlens has a concave shape in a light-emitting
device with a built-in microlens according to a second embodiment
of the present invention. The chalcogenide glass film 21 is
integrally formed on an emission surface of an edge emission
semiconductor laser 10 having an emission layer 10a. This
chalcogenide glass film 21 is an example of the "photosensitive
material" in the present invention.
[0060] A method of forming the light-emitting device with a
built-in microlens according to the second embodiment is now
described with reference to FIGS. 7 and 8.
[0061] First, the chalcogenide glass film 21 consisting of an
As.sub.2S.sub.3 film having a thickness of about 50 .mu.m is formed
on the emission edge of the semiconductor laser 10, as shown in
FIG. 7.
[0062] Then, the semiconductor laser 10 is driven under a condition
increasing light intensity beyond that in the aforementioned
embodiment, as shown in FIG. 8. More specifically, the
semiconductor laser 10 emits a laser beam 100 of about 660 nm with
power of about 100 mW for about 2 minutes. Thus, a portion of the
chalcogenide glass film 21 irradiated with the laser beam 100
emitted from the semiconductor laser 10 is partially evaporated.
Consequently, the microlens consisting of the chalcogenide glass
film 21 having a concave shape is formed. Thus, the optical path
length of the portion strongly irradiated with light is so reduced
as to concavely form the microlens.
[0063] According to the second embodiment, as hereinabove
described, the chalcogenide glass film 21 consisting of an
As.sub.2S.sub.3 film is formed on the emission edge of the
semiconductor laser 10, which in turn is driven under a condition
increasing the intensity of the laser beam 100, whereby the concave
microlens integrated with the semiconductor laser 10 can be easily
formed.
[0064] According to the second embodiment, further, the microlens
consisting of the concave chalcogenide glass film 21 is formed
through the laser beam 100 emitted from the semiconductor laser 10
mounted with the microlens so that the optical axis of the
microlens is automatically aligned in formation of the concave
microlens, whereby the optical axis is not misaligned by patterning
misregistration dissimilarly to a microlens formed by lithography
and etching.
[0065] (Third Embodiment)
[0066] Referring to FIG. 9, a microlens consisting of a convex
chalcogenide glass film 33 is integrally formed on an emission edge
of an edge emission semiconductor laser 10 having an emission layer
10a in a light-emitting device with a built-in microlens according
to a third embodiment of the present invention. The chalcogenide
glass film 33 is an example of the "photosensitive material" in the
present invention.
[0067] A method of forming the light-emitting device with a
built-in microlens according to the third embodiment is now
described with reference to FIGS. 10 and 11.
[0068] First, a chalcogenide glass film 33a consisting of an
As.sub.2S.sub.3 film having a thickness of about 4 .mu.m is formed
on the emission edge of the semiconductor laser 10 by vacuum
deposition, as shown in FIG. 10.
[0069] Thereafter the semiconductor laser 10 is driven under
conditions similar to those in the formation process according to
the first embodiment shown in FIG. 3, thereby irradiating the
chalcogenide glass film 33a with a laser beam 100. More
specifically, the semiconductor laser 10 applies the laser beam 100
of about 660 nm to the chalcogenide glass film 33a with power of
about 50 mW for about 10 minutes. Thereafter an unirradiated
portion and part of the irradiated portion of the chalcogenide
glass film 33a are etched by wet etching employing an alkaline
solution such as an NaOH aqueous solution or plasma etching with
SF.sub.6 or the like, for example. In this etching, the portion
irradiated with the laser beam 100 is hardly etched in response to
the exposure, to result in formation of the convex microlens
consisting of the convex chalcogenide glass film 33 as shown in
FIG. 11.
[0070] The convex shape of the microlens reflects intensity
distribution of the laser beam 100 applied thereto. If the beam
spot is elliptic, therefore, the convex microlens exhibits an
elliptic shape (not shown). The elliptic convex microlens can
substantially circularize the elliptic beam spot. More
specifically, the convex microlens having an elliptic shape
remarkably reduces the major axis direction of the elliptic beam
spot while slightly reducing the minor axis direction thereof,
whereby the beam spot can be substantially circularized.
[0071] According to the third embodiment, as hereinabove described,
the convex microlens integrated with the semiconductor laser 10 can
be easily formed by forming the chalcogenide glass film 33a
consisting of an As.sub.2S.sub.3 film on the emission surface of
the semiconductor laser 10 by vacuum deposition and thereafter
forming the convex microlens by photoirradiation from the
semiconductor laser 10 and etching.
[0072] According to the third embodiment, further, the optical axis
of the microlens is automatically aligned in formation of the
microlens by forming the microlens consisting of the chalcogenide
glass film 33a through the laser beam 100 emitted from the
semiconductor laser 10 mounted with the microlens, whereby the
optical axis is not misaligned by patterning misregistration
dissimilarly to a microlens formed by lithography and etching.
[0073] According to the third embodiment, in addition, a convex
shape can be formed with a portion intensely irradiated with the
laser beam 100 having a large optical path length, whereby a beam
can be formed with small aberration. Thus, coupling efficiency of
the laser beam 100 emitted from the semiconductor laser 10 can be
improved with respect to an optical fiber member or the like.
[0074] (Fourth Embodiment)
[0075] Referring to FIG. 12, a microlens consisting of a
chalcogenide glass film 41 having a photo-irradiated part 42
exhibiting a larger refractive index than that of unirradiated part
and a convex part 43 is integrally formed on an emission edge of an
edge emission semiconductor laser 10 in a light-emitting device
with a built-in microlens according to a fourth embodiment of the
present invention. The chalcogenide glass film 41 consists of an
As.sub.2S.sub.3 film having a thickness of about 4 .mu.m. This
chalcogenide glass film 41 is an example of the "photosensitive
material" in the present invention.
[0076] A method of forming the light-emitting device with a
built-in microlens according to the fourth embodiment shown in FIG.
12 is now described with reference to FIGS. 13 and 14.
[0077] As shown in FIG. 13, the chalcogenide glass film 41
consisting of an As.sub.2S.sub.3 film having the thickness of about
4 .mu.m is formed on the emission edge of the semiconductor laser
10. Thereafter heat treatment is performed at a temperature close
to the glass transition temperature (about 180.degree. C. to about
220.degree. C.) of the AS.sub.2S.sub.3 film. More specifically, the
heat treatment is performed at a temperature of about 180.degree.
C. for about 1 hour. Thereafter the semiconductor laser 10 is
driven to apply a laser beam 100 of about 660 nm to the
chalcogenide glass film 41 with power of about 50 mW for about 1
hour, as shown in FIG. 14. Thus, the refractive index of the
photo-irradiated part 42 is increased due to photoinduced
refractive index change while the volume is also simultaneously
increased due to photoinduced volume expansion. In other words,
expansional deformation of the photo-irradiated part 42 irradiated
with the laser beam 100, starting to expand due to the photoinduced
volume expansion, is restricted by the outer peripheral portion of
the photo-irradiated part 42 not influenced by the photoinduced
volume expansion. Therefore, the photo-irradiated part 42 starting
to expand is stressed, to form a protuberance (convex part 43) on
the free surface portion for relaxing the stress. Consequently, the
convex microlens consisting of the chalcogenide glass film 41 is
formed to have the photo-irradiated part 42 exhibiting a larger
refractive index than that of-unirradiated part and the convex part
43.
[0078] According to the fourth embodiment, as hereinabove
described, the graded index microlens having a convex shape
integrated with the semiconductor laser 10 can be easily formed by
vacuum-depositing the chalcogenide glass film 41, heat-treating the
same at a temperature close to the glass transition temperature
thereof and applying the laser beam 100 from the semiconductor
laser 10 thereto.
[0079] According to the fourth embodiment, further, the optical
axis of the microlens is automatically aligned in formation of the
microlens by forming the graded index microlens having a convex
shape through light emitted from the semiconductor laser 10 mounted
with the microlens, whereby the optical axis is not misaligned by
patterning misregistration dissimilarly to a microlens formed by
lithography and etching.
[0080] According to the fourth embodiment, in addition, a convex
shape can be formed with a portion intensely irradiated with light
having a large optical path length, whereby a beam can be formed
with small aberration. Thus, the coupling efficiency of the laser
beam 100 emitted from the semiconductor laser 10 can be improved
with respect to an optical fiber member or the like.
[0081] (Fifth Embodiment)
[0082] Referring to FIG. 15, a light-emitting device with a
built-in microlens according to a fifth embodiment of the present
invention has a structure obtained by adding a transparent
insulating spacer 53 between a semiconductor laser 10 and a
microlens in a structure similar to that of the first embodiment
shown in FIG. 1.
[0083] In the light-emitting device with a built-in microlens
according to the fifth embodiment, a graded index microlens
consisting of a chalcogenide glass film 51 having a
photo-irradiated part 52 exhibiting a larger refractive index than
that of unirradiated part is integrally formed on an emission edge
of the edge emission semiconductor laser 10 having an emission
layer 10a through the transparent insulating spacer 53, as shown in
FIG. 15. The spacer 53 consists of a GeO.sub.2 film formed by
high-frequency sputtering, for example, and has a thickness of
about 5 .mu.m to about 100 .mu.m. The chalcogenide glass film 51
constituting the microlens consists of an As.sub.2S.sub.3 film
having a thickness of about 4 .mu.m. The chalcogenide glass film 51
is an example of the "photosensitive material" in the present
invention.
[0084] According to the fifth embodiment, as hereinabove described,
the transparent insulating spacer 53 is provided between the
semiconductor laser 10 and the chalcogenide glass film 51 so that
the distance between a beam spot position on the emission edge of
the semiconductor laser 10 and the chalcogenide glass film 51 can
be varied by adjusting the thickness of the spacer 53, thereby
varying imaging characteristics of the microlens. The insulating
spacer 53 can alternatively be formed by air. For example,
chalcogenide glass may be bonded to a window member of a laser
cover for mounting a microlens on the bonded chalcogenide
glass.
[0085] The remaining effects of the fifth embodiment are similar to
those of the aforementioned first embodiment.
[0086] (Sixth Embodiment)
[0087] Referring to FIG. 16, a light-emitting device with a
built-in microlens according to a sixth embodiment of the present
invention has a structure obtained by adding antireflection
coatings 63a and 63b to a structure similar to that according to
the first embodiment shown in FIG. 1.
[0088] According to the sixth embodiment, the antireflection
coatings 63a and 63b are formed between an emission edge of an edge
emission semiconductor laser 10 having an emission layer 10a and a
chalcogenide glass film 61 and on the surface of the chalcogenide
glass film 61 respectively, as shown in FIG. 16. The antireflection
coatings 63a and 63b are formed by CdSe films of about 100 nm in
thickness formed by high-frequency sputtering. According to the
sixth embodiment, the chalcogenide glass film 61 is so formed as to
increase the refractive index of a photo-irradiated part 62,
thereby forming a graded index microlens having the
photo-irradiated part 62 exhibiting a larger refractive index than
that of unirradiated part. The chalcogenide glass film 61 is an
example of the "photosensitive material" in the present invention.
The antireflection coatings 63a and 63b are examples of the "first
antireflection coating" and the "second antireflection coating" in
the present invention respectively.
[0089] According to the sixth embodiment, as hereinabove described,
the antireflection coatings 63a and 63b are so provided that the
light-emitting device can be prevented from multiple reflection,
whereby the characteristics of the microlens consisting of the
chalcogenide glass film 61 can be improved.
[0090] In a process of forming the aforementioned light-emitting
device with a built-in microlens according to the sixth embodiment,
the antireflection coating 63a, the chalcogenide glass film 61 and
the antireflection coating 63b are successively formed on the edge
of the semiconductor laser 10 emitting light, for thereafter
applying a laser beam 100 of about 660 nm to the chalcogenide glass
film 61 with power of about 50 mW for about 10 minutes, similarly
to the process of forming the light-emitting device with a built-in
microlens according to the first embodiment shown in FIG. 3. Thus,
the graded index microlens is formed with the photo-irradiated part
62 having a larger refractive index than that of unirradiated part,
as shown in FIG. 16.
[0091] Also in the sixth embodiment, the optical axis of the
microlens is automatically aligned in formation of the microlens by
forming the microlens through light emitted from the semiconductor
laser 10 mounted with the microlens similarly to the aforementioned
first to fifth embodiments, whereby the optical axis is not
misaligned by patterning misregistration dissimilarly to a
microlens formed by lithography an etching.
[0092] Further, the microlens integrated with the semiconductor
laser 10 can be easily formed by successively forming the
antireflection coating 63a, the chalcogenide glass film 61 and the
antireflection coating 63b on the emission edge of the
semiconductor laser 10 and thereafter applying light from the
semiconductor laser 10 to the chalcogenide glass film 61.
[0093] (Seventh Embodiment)
[0094] Referring to FIG. 17, a microlens consisting of a
chalcogenide glass film 73 integrated with a semiconductor laser 10
is formed through a process basically different from those of the
aforementioned first to sixth embodiments in a light-emitting
device with a built-in microlens according to a seventh embodiment
of the present invention. The chalcogenide glass film 73 is an
example of the "photosensitive material" in the present
invention.
[0095] More specifically, a chalcogenide glass film 71 is arranged
in proximity to an emission edge of a semiconductor laser 10 at an
interval of about 1 .mu.m to about 10 .mu.m from the emission edge,
as shown in FIG. 17. In this state, the semiconductor laser 10 is
driven to apply a laser beam 100 to the chalcogenide glass film 71.
More specifically, the semiconductor laser 10 applies the laser
beam 100 of about 660 nm to the chalcogenide glass film 71 with
power of about 100 mW for about 2 minutes. Thus, the portion of the
chalcogenide glass film 71 irradiated with the laser beam 100 is
evaporated to convexly adhere to the emission edge of the
semiconductor laser 10. Thereafter the chalcogenide glass film 71
is so removed that the convex chalcogenide glass film 73 operates
as a convex microlens.
[0096] According to the seventh embodiment, as hereinabove
described, the convex microlens integrated with the semiconductor
laser 10 can be easily formed by arranging the chalcogenide glass
film 71 in proximity to the emission edge of the semiconductor
laser 10 and thereafter applying the laser beam 100 emitted from
the semiconductor laser 10 to the chalcogenide glass film 71
thereby partially evaporating the chalcogenide glass film 71.
[0097] Also in the seventh embodiment, the optical axis of the
microlens is automatically aligned in formation of the microlens by
forming the microlens through the laser beam 100 emitted from the
semiconductor laser 10 mounted with the microlens, whereby the
optical axis is not misaligned by patterning misregistration
dissimilarly to a microlens formed by lithography and etching.
[0098] According to the seventh embodiment, further, a convex shape
can be formed with a portion intensely irradiated with light having
a large optical path length, whereby a beam can be formed with
small aberration. Thus, the coupling efficiency of the laser beam
100 emitted from the semiconductor laser 10 can be improved with
respect to an optical fiber member or the like.
[0099] Although the present invention has been described and
illustrated in detail, it is clearly understood that the same is by
way of illustration and example only and is not to be taken by way
of limitation, the spirit and scope of the present invention being
limited only by the terms of the appended claims.
[0100] For example, while each of the above embodiments has been
described with reference to the microlens formed on the emission
edge of the edge emission semiconductor laser employed as an
exemplary semiconductor light-emitting device, the present
invention is not restricted to this but is also applicable to a
microlens formed on an emission surface of another semiconductor
light-emitting device such as a surface emission semiconductor
laser or a light-emitting diode.
[0101] While each of the aforementioned embodiments employs the
chalcogenide glass film consisting of As.sub.2S.sub.3 as the
photosensitive material for forming the microlens, the present
invention is not restricted to this but similar effects can also be
attained by employing a chalcogenide glass film consisting of
another material or a photosensitive material consisting of
photoreactive organic matter, for example. More specifically, it is
preferable to employ As.sub.2S.sub.3 or GeSe.sub.2 for a red laser,
As.sub.2Se.sub.3 or the like for an infrared laser, or GeS.sub.2 or
the like for a blue-green laser. Photoreactive organic matter such
as micro-negative resist (by Eastman Kodak Co.) or photoresist is
preferably employed for an ultraviolet laser.
[0102] While the graded index microlens having a concave shape
integrated with the semiconductor laser 10 is formed by
vacuum-depositing the chalcogenide glass film 41, thereafter
performing heat treatment at the temperature close to the glass
transition temperature thereof and irradiating the chalcogenide
glass film 41 with the light emitted from the semiconductor laser
10 in the aforementioned fourth embodiment, the present invention
is not restricted to this but a graded index microlens having a
convex shape integrated with a semiconductor laser similar to that
according to the fourth embodiment can also be formed by forming a
chalcogenide glass film by high-frequency sputtering and thereafter
applying a laser beam from a semiconductor laser to the
chalcogenide glass film under conditions similar to those in the
fourth embodiment.
[0103] While the light-emitting device with a built-in microlens
according to the aforementioned fifth embodiment has the structure
obtained by adding the transparent insulating spacer 53 to the
structure similar to that according to the first embodiment, the
present invention is not restricted to this but the spacer 53 may
alternatively be added to a structure similar to that according to
any of the second to fourth and sixth and seventh embodiments. Also
in this case, the distance between the beam spot position on the
emission edge of the semiconductor laser 10 and the chalcogenide
glass film 21, 33, 41, 61 or 73 can be varied by adjusting the
thickness of the spacer 53, thereby varying imaging characteristics
of the microlens.
[0104] While the fifth embodiment has been described with reference
to the spacer 53 formed by a GeO.sub.2 film, the present invention
is not restricted to this but another transparent film or air may
alternatively be employed. When air is employed as the-spacer 53,
the microlens is mechanically fixed to the periphery of the
emission part of the semiconductor laser 10.
[0105] While the antireflection coatings 63a and 63b are added to
the structure similar to that according to the first embodiment in
the aforementioned sixth embodiment, the present invention is not
restricted to this but the antireflection coatings 63a and 63b may
alternatively be added to a structure similar to that of any of the
second to fifth embodiments and the seventh embodiment. Also in
this case, multiple reflection can be so suppressed that the
characteristics of the microlens can be improved.
[0106] While the antireflection coatings 63a and 63b consist of
GeO.sub.2 films in the aforementioned sixth embodiment, the present
invention is not restricted to this but the antireflection coatings
63a and 63b may alternatively be formed by other films of
SiO.sub.2, SiN, TiO.sub.2 or the like having antireflection
functions.
* * * * *