JPH11233889A - Flat type light amplifier element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical element which can produce light easily in high volume with high precision by making the element in such a structure that a light amplifying function section is attached to a transparent supporting substrate and light is made incident to an active layer through the transparent supporting substrate and light beam is emitted from the active layer. SOLUTION: A light amplifying function section 11 having such a structure that an active layer 13 for generating exciting carriers is put from up and down by a p-type and an n-type semiconductor layer 14, 12 is attached with a transparent adhesive 22 to a transparent substrate 21 which is different from a substrate on which the light amplifying function section 11 is built. Light beam generated in the active layer 13 is reflected on a reflecting mirror 14 and is radiated into an outside space from an n-type clad layer 12 through the transparent substrate 21. By locating a flat-type dielectric multilayer film reflecting mirror on the extension line of a light beam emission path in the outside space, an outside reflecting mirror-type surface emission laser can be formed in a complete form. For the active layer 13 to generate exciting carriers, current needs to be injected into the active layer 13. In this case, current is injected by means of a divided electrode 16 for injecting holes which have been divided into a plurality of electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a surface type optical amplifying device which can be used as a surface emitting laser or the like by providing a resonator outside the device, and a method of manufacturing the same. Here, the “surface-type” optical amplifying element means that the emitted light from the optical function part that amplifies and emits light is a specific light with respect to the surface of the substrate that physically supports the light amplification function part. It means that the light is emitted in a direction rising at an angle, generally in a direction orthogonal (normal direction).

[0002]

2. Description of the Related Art Conventionally, as a surface-type optical amplifying element of this kind, reference 1: "Electrically pumped mode-locked ver.
tical-cavity semiconductor lasers "(W. Jiang, M. Shimi
zu, RPMirin, TEReynolds, and JEBowers, Optics
Letters, vol 18, No. 22, pp. 1937-1939, 1993) and shown in FIG. 2 is known. From a structural point of view, the surface-type optical amplifying element 30 includes an n-type GaAs substrate 31, an n-type semiconductor multilayer mirror 32, an n-type cladding layer 33, and an n-type GaAs active layer 3.
4. The p-type cladding layer 35, the p-type AlGaAs layer 37, and the p-type GaAs contact layer 38 are laminated. p-type AlGaAs layer 37 and p-type
The GaAs contact layer 38 is cut out into a predetermined plane area shape, and the upper surface thereof is provided with an anti-reflection coating 39. On the other hand, around the cut out portion, an insulating film 36 is sandwiched.
The surface electrode 40 formed on the p-type cladding layer 35 is
The n-type substrate 31 contacts the periphery of the upper surface of the As contact layer 38.
The substrate electrode 41 is formed on the back surface of the substrate.

[0003] Carrier injection into the n-type GaAs active layer 34 is performed by current injection by applying a voltage between the surface electrode 40 and the substrate electrode 41, and holes are formed from the side of the surface electrode 40 into the p-type GaAs contact layer 38, n-type Ga through the p-type AlGaAs layer 37 and the p-type cladding layer 35
The electrons are injected into the As active layer 34, and the electrons are
31, n-type semiconductor multilayer reflector 32, and n-type cladding layer 33
Is injected into the n-type GaAs active layer.

[0004] When the conventional element 30 is used as an optical amplifying element, or in particular, as a surface emitting laser, a resonator is constructed by using an n-type semiconductor multilayer film reflecting mirror 32 constructed inside the element as one reflecting mirror means. A non-external reflecting mirror is configured as the other reflecting mirror. Generally, a lens (not shown) is provided between an external reflection mirror (not shown) and the anti-reflection coating 39. The anti-reflection coating 39 is, of course, used to reduce resonator loss and obtain optical gain. For the same purpose, the layers 33 to 35, 37, and 38 sandwiched between the pair of reflecting mirrors are also provided with measures such as, for example, keeping the impurity concentration low so as to reduce optical absorption loss. .

FIG. 3 shows another conventional example. This planar optical amplifier 50 is described in Reference 2: "High single
-transverse-mode output from external-cavity surfa
ce-emitting laser diodes "(MAHadley, GC Wilson, K.
Y.Lau, and JSSmith, Appl.Phys.Lett., Vol.63, No.12, p
(pp. 1607-1609, 1993), in which a p-type GaAs substrate 51 is used as the substrate 51 instead of an n-type, and a p-type semiconductor multilayer film reflecting mirror 52 and a p-type multiple quantum Well active area
53, an n-type semiconductor multilayer reflector 55 is laminated in order,
A voltage is applied between a substrate electrode 57 provided on the back surface of the substrate 51 and a bonding pad 56 provided on the insulating film 54, in contact with the surface periphery of the n-type semiconductor multilayer film reflecting mirror 55, and a multiple quantum well is formed. By injecting current (carrier) into the active region 53, excitation light is obtained. In the multiple quantum well active region 53, holes are injected from the substrate electrode 57 side through the p-type GaAs substrate 51 and the p-type semiconductor multilayer reflector 52, and electrons are reflected from the opposing bonding pad 56 into the n-type semiconductor multilayer film. Mirror 55
Injected through.

[0006] This element 50 is not originally an element for an external resonator. However, if the resonator is constituted only by the n-type semiconductor multilayer film reflecting mirror 55 and the p-type semiconductor multilayer film reflecting mirror 52 built in the element, if the aperture is enlarged, almost always,
There is a disadvantage that the transverse mode is not monomodal. In order to compensate for this disadvantage, an external reflector (not shown) is also required, and the reflectivity of the n-type semiconductor multilayer film reflector 55 is intentionally reduced, and then the n-type semiconductor multilayer film reflector 55 A suitable reflecting mirror is provided outside the element, and a monomodal beam is obtained by adjusting, for example, the position of a lens disposed in the optical path to the external reflecting mirror. In any case, the configuration of the resonator is a composite type to the last, and the first resonator including the p-type semiconductor multilayer film reflecting mirror 52 and the n-type multilayer film reflecting mirror 55 provided on the substrate side provided inside the element, The second resonator including the p-type semiconductor multilayer film reflecting mirror 52 and the external reflecting mirror is combined.

[0007]

However, in the case of the element 30 shown in FIG. 2, it has been particularly difficult to obtain a large-diameter laser beam. This is because n-type Ga
The effective area of the As active layer 34, that is, the anti-reflection coating 39
This is because, if the area of the region which is actually covered by the oscillation and which actually contributes to the oscillation is increased, it becomes impossible to uniformly inject holes there. This is exclusively for each of the p-type semiconductor layers 38, 37, 35
In order to inject holes near the center of the n-type GaAs active layer effective area, the surface electrode 40 in contact with the periphery of the anti-reflection coating 39 needs p
It is necessary to first flow holes in the in-plane direction in the semiconductor layers 38, 37, and 35 of the mold, and then to inject them into the center of the n-type GaAs active layer 34. The portion is injected from the surface electrode 40 to the peripheral portion of the p-type GaAs contact layer 38, and then proceeds almost straight to the n-type GaAs active layer 34 without widening in the lateral direction.

In fact, in the conventional device 30 manufactured according to such a structural principle, in order to ensure a state where uniform hole injection can be recognized in the n-type GaAs active layer 34, the n-type GaAs is required.
The diameter of the effective region of the active layer 34 must be kept to several tens of μm or less. As a result, in order to increase the output power, it is necessary to adopt a method such as arraying a plurality of elements. The quality and uniformity had to be sacrificed.

On the other hand, in the conventional device 50 shown in FIG.
Since holes can be injected from the substrate electrode 57 brought into surface contact with the back surface of the As substrate 51, the uniformity of the in-plane distribution of holes injected into the multiple quantum well active region 53 can be taken to a satisfactory degree. However, since the most problematic is the complex resonator structure, a pure external cavity surface emitting laser cannot be formed, and furthermore, it is built into the device.
Since the n-type semiconductor multilayer reflector 55 usually has a reflectivity of about 80% or more, it is not suitable for use as a planar optical amplifier. Also, because of the composite resonator structure,
An optical pulse cannot be generated by the mode locking operation.

Further, electrons are injected also in the vicinity of the center of the multiple quantum well active region 53 by using an n-type semiconductor multilayer film reflecting mirror 55 having a lower resistance than the p-type and flowing electrons in the in-plane direction. However, when the diameter of the multiple quantum well active region 53 is increased, the electrical resistance of the n-type semiconductor multilayer reflector 55 cannot be ignored, and non-uniform current injection occurs. The effective area of the multiple quantum well active region 53, which can be regarded as being uniformly implanted, is
Although it can be widely used as compared with the conventional element 30 shown in FIG. 2, the upper limit is about 100 μm in diameter. In particular, since the p-side electrode is a substrate electrode and current is injected through the substrate, injection of holes into the active layer cannot be controlled.

The present invention has been made in view of the above point, and has at least a light amplification function portion including a structure in which an active layer is sandwiched between p-type and n-type cladding layers, and has a predetermined angle with respect to the surface of the supporting substrate. (Generally 90 ° as described above) In a surface-type optical amplifying element that emits a light beam in the rising direction,
It is intended to provide a single, uniform, and, if necessary, element capable of amplifying a large-diameter light beam and also performing laser oscillation.

[0012]

The inventor of the present invention has found that the various disadvantages of the conventional devices 30 and 50 shown in FIGS. 2 and 3 are that an optical amplification function part which ultimately contributes to the amplification of light, that is, FIG. In the conventional device 30 shown in the drawings, the laminated structure portion including the semiconductor layers 32 to 35, 37, and 38, and in the conventional device 50 shown in FIG.
This was attributed to the existence of the n-type substrate 31 or the p-type substrate 51, which constitutes the laminated structure portion including 3, 55, itself.

Of course, these substrates 31 and 51 are indispensable for constructing the optical amplification function part, and have sufficient significance as a support substrate for ensuring the physical strength of the element even after construction. However, with respect to the optical amplification function, the substrates 31 and 51 are unnecessary or obstructive.
For example, the substrates 31 and 51 to be used generally have a considerable thickness of several hundred μm. Therefore, when a compound semiconductor substrate such as a GaAs substrate is used as the substrate, the loss is too large to transmit the amplified light. .

As a result, both the conventional element 30 shown in FIG. 2 and the conventional element 50 shown in FIG. 3 have a configuration in which the amplified light does not pass through the supporting substrates 31 and 51, and other elements not described. This is the same in the conventional configuration. In other words, even if various structural measures are conventionally taken to improve the device characteristics, it is necessary to do so on the premise that light does not pass through the substrate. It was. For example, in the case of the conventional device 30 shown in FIG. 2, the light emitted from the optical amplification function portion is emitted from the p-type semiconductor layers 35, 37, and 38 on the surface opposite to the n-type GaAs substrate 51. Therefore, the emission surface cannot be covered with the electrode, and as a result, the p-type cladding layer 35 and the n-type GaAs active layer 34 only pass through the peripheral portion of the p-type AlGaAs layer 37 as described above. Therefore, it is necessary to establish conduction, which causes the above-described non-uniformity of hole injection and difficulty in increasing the diameter.

In the case of the conventional device 50 shown in FIG.
Although the p-type GaAs substrate 51 is used in place of the As substrate, and the n-type semiconductor multilayer reflector 55 can be used on the surface opposite to the substrate, there is an advantage that the resistance can be reduced. There are still restrictions, such as the need to use a container structure, which also has another drawback as described above.

Therefore, the present inventor departed from the conventional common sense and obtained the idea of removing the base substrate used for constructing the optical amplification function part after constructing the optical amplification function part. Was. However, mere removal simply does not have the strength of the optical amplification function, which is a very thin structure.
It is not practical because physical distortion produces optical distortion. Therefore, instead, in the present invention, a structure in which the optical amplification function portion is bonded to a low-loss transparent substrate that transmits a light beam and is different from the supporting substrate different from the construction substrate used for its construction. Suggest.

With such an element structure, the light beam amplified by the light amplification function portion can be passed through the transparent substrate. This means that there is a degree of freedom in the structure of the optical amplification function, and for example, the electrode for injecting holes into a relatively high-resistance p-type semiconductor layer has a large area, As in the specific embodiment, even if the electrode is constituted by a plurality of divided electrodes so that light is not emitted from one surface side of such an electrode, the transparent electrode provided on the opposite side with the active layer in the optical amplification function portion interposed therebetween. By allowing the light beam to be emitted through the substrate, various improvements can be made.

After satisfying these basic conditions, as a desirable lower aspect of the present invention, the optical amplification function portion is bonded to a transparent substrate on one side of the n-type semiconductor layer, and is formed on the opposite side of the active layer with the p-type semiconductor layer therebetween. A surface-type optical amplifying element in which a hole is injected into a semiconductor layer, which is a divided electrode divided into a plurality, is also proposed.

In such a planar optical amplifier, the injection of holes into the p-type semiconductor layer having a higher resistance than that of the n-type can be made uniform, and the amount of current injected into each of the divided electrodes can be controlled. Can control the in-plane distribution of carriers in the active layer, so that it is possible to control to match the light intensity distribution in the unimodal fundamental mode.

Further, as a more specific lower aspect, according to the present invention, the active layer in the optical amplification function portion has an n-type semiconductor cladding layer as an n-type semiconductor layer and a p-type semiconductor layer as a p-type semiconductor layer.
The optical amplification function part is adhered to the transparent substrate on the side of the n-type semiconductor cladding layer, and the divided electrodes are provided on the p-type semiconductor multilayer reflection mirror. Conduction through the p-type cap layer and n
The present invention proposes a surface-type optical amplifying element in which an electrode conducting to a mold semiconductor cladding layer is connected to a wiring conductor provided on a surface of a transparent substrate.

According to the present invention, a method of manufacturing a planar optical amplifying device also includes a method of constructing an optical amplifying function part on a construction substrate for constructing the optical amplifying function part, and then removing the construction substrate. There is also proposed a method including a step of bonding the exposed surface side of the optical amplification function portion to another transparent substrate, and then removing the build substrate.

In this case, the present invention provides
An active layer and an n-type semiconductor layer are formed in this order on the construction substrate from the p-type semiconductor layer, and the transparent substrate is adhered to the exposed surface side of the n-type semiconductor layer, and the p-type exposed by removing the construction substrate A manufacturing method is also proposed in which a plurality of split electrodes that conduct to the p-type semiconductor layer are formed on the surface on the semiconductor layer side.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a schematic diagram showing an example of a planar optical amplifier 10 constructed according to the present invention. In the case of the present invention, the optical amplification function portion 11 including the structure in which the active layer 13 for generating excited carriers is sandwiched between the p-type and n-type semiconductor layers 14 and 12 from above and below is formed.
Is adhered to a transparent substrate 21 different from the substrate on which is constructed by a transparent adhesive 22. That is, in FIG. 1A, the construction substrate is shown in a state where it has been already removed.

However, in the case of the device 10 of the present invention,
Since the light beam generated by the light amplification function part 11 can pass through the transparent substrate 21, the light amplification function part 11
The degree of freedom of structural improvement for is increased. In FIG. 1A, as described below, an example of a desirable structure in a lower aspect according to the present invention is disclosed. However, in addition to this, a planar optical amplifier according to the basic configuration of the present invention is disclosed. Various elements can be provided.

The transparent substrate 21 may be selected to have as high transparency as possible to the oscillation wavelength, and suitable materials such as glass and plastic can be obtained. As high as 99% to 99.9% can be easily obtained. However, no matter how high the transmittance, the loss increases if the thickness is too large. However, normally, in the range of the thickness that can physically support the optical amplification function portion 11 and secure the strength that can prevent the distortion, even if the thickness is considerably increased to several hundred μm to several millimeters, it is sufficient. And a satisfactory transmittance is obtained.

A suitable adhesive such as polyimide is also commercially available as the transparent adhesive 22, and its transmittance is sufficiently high.
It doesn't matter because it can be very thin in the first place. The flattening of the surface of the transparent substrate 21 (higher optical precision) and the uniform application of the transparent adhesive 22 can be performed to a satisfactory degree even with existing techniques. Further, the surface interface of the transparent substrate 21, the transparent substrate 21 and the transparent adhesive 22, the transparent adhesive 22 and the optical amplification function portion 11
In order to avoid irregular reflection at the interface with the surface, it is preferable to previously apply anti-reflection coatings 25, 24, and 23 on those surfaces, respectively. These are, for example, a two-layer laminated structure layer of TiO ₂ and SiO _2. Can be configured.

FIG. 1A shows a planar optical amplifier 10 according to the present invention.
In this case, the configuration of the optical amplification function part 11 is specifically as follows. First, the n-type cladding layer 12 adhered to the transparent substrate 21 via the transparent adhesive 22 and the anti-reflection coating 23 has a thickness of, for example, 2 nm.
It can be composed of an n-type Al _X Ga _1-X As (x = 0.3) layer of about μm.

On top of this, an active layer 13 for generating excited carriers, which is a main part of the optical amplification function part 11, is formed, for example, a non-doped GaAs having a thickness of about 0.5 μm.
It can be composed of layers.

On the active layer 13, a p-type semiconductor multilayer mirror 14 is formed as a p-type semiconductor layer in this case.
This can be achieved, for example, by a periodic repetitive lamination structure of p-type Al _X Ga _1-X As (x = 0.1) and p-type AlAs layer, and one layer is considerably thinner, and the total thickness is about several μm. To However, since such a semiconductor multilayer film reflecting mirror itself is already known, it may be manufactured according to an arbitrary technique.

However, in the case of the planar optical amplifier 10 shown in FIG. 1A, as can be seen from the fact that the semiconductor multilayer reflector 14 is used as the p-type semiconductor layer, as shown in FIG.
The light beam generated at is reflected by the reflecting mirror 14, and n
The structure is such that radiation is emitted from the mold cladding layer 12 to the external space via the transparent substrate 21. Therefore, although not shown, a high-performance reflecting mirror already developed, for example, having a reflectivity of 99%, is provided in an external space on the extension of the light beam emission path, if necessary, with an appropriate lens interposed therebetween. By arranging the planar dielectric multilayer film reflecting mirror and the like as described above, a complete shape can be obtained without depending on the complex resonator structure used in combination with the resonator inside the device as in the conventional device shown in FIG. An external reflecting mirror type surface emitting laser can be configured.

Of course, in order to generate excited carriers in the active layer 13, it is necessary to inject current into the active layer 13. The configuration for this is as follows in the case of the illustrated element 10. Here, too, desirable measures have been taken.

First, on the p-type semiconductor multilayer film reflecting mirror 14,
For example, p-type of about 3000Å doped with high concentration of Zn
A p-type cap layer 15 of a GaAs layer is formed, on which a
Desirably, a plurality of divided hole injection electrodes 16 are formed. In the case of the drawing, a plurality of annular electrodes are arranged concentrically at a predetermined pitch around a central disk-shaped electrode. In this way, by individually adjusting the voltage applied to each electrode, the surface of the hole injected into the active layer 13 from each electrode via the p-type cap layer 15 and the p-type semiconductor multilayer film reflecting mirror 14 is obtained. The internal distribution can be adjusted to be uniform, and active control can be performed during operation.

That is, conventionally, when holes are injected into the active layer through the high-resistance p-type semiconductor layer, which is also a considerably thin p-type semiconductor layer, the hole flow is inevitably biased and uniform injection cannot be performed. In contrast, according to the illustrated configuration,
In addition to enabling uniform hole injection into the active layer 13, it is also possible to more positively control the injection current distribution so that the gain distribution is adapted to the light distribution such as the oscillation mode. For example, when it is desired to obtain a light distribution of a unimodal fundamental mode, generally, the amount of injected current should be increased as the central electrode is passed. Further, it is possible not only to obtain a stable and highly accurate oscillation light, but also to obtain an oscillation light beam having a desired far-field pattern.

The split electrodes 16 are not limited to concentric ones as shown in the figure. It can be a pattern in which a plurality of strips are arranged side by side, each one is a dot shape of an appropriate plane shape such as a circle or a square, and a plurality of these are arranged in a predetermined plane pattern However, the point is arbitrary.

On the other hand, an electrode for injecting electrons into the n-type semiconductor layer 12 having a relatively low resistance can be made a little more roughly. In the case shown in the drawing, the entire surface is in contact with the lower surface of the n-type semiconductor layer (cladding layer) 12 along the outer periphery of the optical amplification function portion 11 cut out into a predetermined three-dimensional shape (in the case shown, a cylindrical shape). An annular contact layer 17 is provided, and an electrode 18 made of AuGe alloy or the like provided on the surface thereof is formed on the surface of the transparent substrate 12 around the optical amplification function portion 11 through an electrode connecting material 19. It is electrically connected to the conductor 20. The contact layer 17 is, for example, an n-type having a thickness of about 1000 mm.
The electrode connecting member 19 can be formed of In or AuSn solder, and the wiring conductor 20 can be formed of Au or the like.

As described earlier, when the device 10 shown in the figure is used as an external cavity surface emitting laser, the cavity structure is a p-type semiconductor multilayer film reflecting mirror 14, an external reflecting mirror and a lens (not shown). It can be composed of Of course, the lens is disposed in an external space on the side where the transparent substrate 21 is located with respect to the active region 13, and the external reflection mirror is disposed on an extension of a line connecting the transparent substrate 21 and the lens. That is, the surface element 10 is arranged so that the transparent substrate 21 faces the external reflection mirror, and the lens is arranged therebetween. The element, lens and external reflecting mirror are mounted on a fine adjustment table that can be adjusted optically. As the external reflecting mirror, for example, a dielectric multilayer film reflecting mirror having a reflectance of 99% or more is used as a plane reflecting mirror that reflects the oscillation wavelength with a sufficiently high reflectance.

The light reflected by the p-type semiconductor multilayer film reflecting mirror 14 is again amplified in the active region 13, collimated through a lens, reflected again by the external reflecting mirror, and
Laser oscillation is generated by repeating the operation of returning to the p-type multilayer film reflecting mirror 14 and again, and at this time, using an adjustment mechanism such as a fine adjustment table, an element, a lens, Optically adjust the external reflector. The distance between the external reflecting mirror and the element, that is, the distance between the external resonators is sufficiently short.
This is to prevent the influence of vibration and the like.

The current to be injected into the split electrode 16 is set so as to coincide with, for example, the light intensity distribution of the unimodal fundamental mode, that is, a large amount of current flows through the central electrode. This makes it possible to realize a high-output external cavity surface emitting laser. Also, when the current injected into the split electrode 16 is subjected to a modulation suitable for the round-trip time of the light of the external resonator length, for example, if the round-trip time of the light is 1 ns, a modulation of 1 GHz is applied to the active mode-locking operation. Is performed, and it becomes possible to generate an optical pulse.

Starting with the surface-type optical amplifying device 10 shown in FIG.
Although the surface type optical amplifying device according to the present invention can be manufactured by various methods, a preferable manufacturing process for the device 10 shown in FIG. 1A can be exemplified with reference to FIG. 1B. First, as shown in Step 101, a commercially available GaAs substrate having a thickness of about 400 μm was used as a construction substrate for constructing an optical amplification function part, and an etching stop layer functioning in future etching was formed thereon. An Al _X Ga _1-X As (x = 0.6) layer is formed to about 3000 °.

On top of that, as shown in step 102, the optical amplifying function part 11 of FIG. 1A is constructed in a relationship just turned upside down on the drawing. That is, the split electrode 16 is not yet manufactured at this time, and the p-type cap layer 15
P-type semiconductor layer multilayer mirror 14, active layer 13, n
The mold cladding layer 12 and the contact layer 17 are stacked and formed, and a light amplification function portion 11 having a predetermined three-dimensional shape, for example, a column shape, is constructed by appropriately using a lithography technique or the like. Similarly, the portion of the contact layer 17 having a large optical loss on the path of the beam is removed by using the lithography technique, and if necessary, the anti-reflection coating 23 is also formed while using the lithography technique.

Next, as shown in step 103, a transparent substrate such as a glass substrate having a sufficiently high surface flatness is provided on the exposed side of the n-type cladding layer 12, that is, on the side of the anti-reflection coating 23, if any. 21 is adhered with a transparent adhesive 22, such as polyimide, applied as uniformly as possible.

In this way, the physical strength of the optical amplifying function portion 11 is secured in advance so that physical and optical distortions do not occur, and then the process proceeds to the step of removing the construction substrate. Since the construction board is as thick as about 400 μm as described above,
First, as shown in 104, this is polished by a mechanical polishing method or the like so as to have a predetermined thickness, for example, a remaining thickness of about 30 to 100 μm.

When the thickness is reduced to the predetermined thickness, step 10
As shown at 5, suitable temperature, suitable solution, e.g. temperature
At about 20 ° C., the remaining thickness of the built substrate is etched with a mixed solution of ammonia and hydrogen peroxide solution at about 1:20. At this time, Al _X Ga _1-X As (x = 0.6) was used as an etching stop layer as described above.
When a layer is used, a high-speed etching of about 20 μm / min can be performed up to the etching stop layer without strictly controlling the etching time, but the etching can be stopped there. As an etching stop layer,
In addition, an AlAs layer or the like can be used.

Thereafter, as shown in step 106, for example, a mixed solution of phosphoric acid, hydrogen peroxide and water (eg, H ₃ PO ₄ :
Using H ₂ O ₂ : H ₂ O = 3: 1: 50), the etching stopper layer itself is etched and removed at a temperature of about 20 ° C. Since the etching rate at this time is about 1000 ° / min, it is easy to remove only the etching stop layer by time management.

When the surface of the p-type cap layer 15 of the optical amplification function portion 11 is exposed in this way, as shown in step 107, an AuZn alloy or the like is entirely deposited and then a lithography technique or a predetermined pattern is used. By the printing technology according to the above, the divided electrodes for hole injection of a predetermined number and a predetermined arrangement pattern
Form 16.

Of course, although not described, the electrode structures 17 to 20 for the n-type semiconductor layer (cladding layer) 12 can be manufactured by a known process using appropriate steps.

Although the preferred embodiment of the present invention has been described above, any modifications can be made freely as long as the purpose of the present invention is met. As a material that can be used for the optical amplification function part 11, in addition to the AlGaAs-based material illustrated,
An nGaAsP-based or GaN-based material can be used, and an optical semiconductor material such as a ZnSe-based II-VI group semiconductor can also be used.

[0048]

According to the present invention, the substrate used for constructing the optical amplifying function can be removed and light can be transmitted to the transparent substrate side. The degree greatly increases.

Further, according to a specific embodiment of the present invention, if the electrode for hole injection on the p-type semiconductor layer side is a plurality of divided electrodes, by controlling the current injected to each electrode, It is possible to actively control the carrier distribution in the active layer. As a result, when constructing an external cavity surface emitting laser, carriers can be injected in accordance with the light intensity distribution of the unimodal fundamental mode, and the operation in the fundamental mode can be stabilized. .

Furthermore, if the transparent substrate side is used as an emission port, the p-type semiconductor layer can be configured as a multilayer film reflecting mirror, so that the optical stability of the p-type multilayer film reflecting mirror obtained by fixing to the transparent substrate can be obtained. This makes it possible to expand the range of the effective active region, thereby realizing a current-injection type, high-output external cavity surface emitting laser, a large-diameter light beam reflection amplifier, and the like. Generation of a light beam with a diameter of several hundred μm or more is sufficiently feasible. of course,
Since the surface optical amplifier of the present invention is of the current injection type, it is possible to realize an external cavity type active mode-locked surface emitting laser. In this case, a high-output light pulse can be generated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a surface-type optical amplifying element of the present invention and a manufacturing process thereof.

FIG. 2 is a schematic configuration diagram of a typical example of a conventional planar optical amplifier.

FIG. 3 is a schematic configuration diagram of another typical example of a conventional planar optical amplifier.

[Explanation of symbols]

 10 Surface-type optical amplifier element of the present invention 11 Optical amplification function part 12 n-type cladding layer 13 active layer 14 p-type semiconductor multilayer mirror 15 p-type cap layer 16 split electrode 17 contact layer 18 electrode 19 electrode connecting material 20 wiring conductor 21 Transparent substrate 22 Transparent adhesive 23, 24, 25 Non-reflective coating

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[Procedure amendment]

[Submission date] January 14, 1999

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Claims (5)

[Claims] 1. An active layer for generating excited carriers is a p-type.
A surface-type light amplifying element having a light amplifying function portion including a structure sandwiched between n-type semiconductor layers and emitting a light beam in a direction rising at a predetermined angle with respect to the surface of a support substrate; A portion is adhered to another transparent substrate different from the substrate on which the optical amplification function portion is constructed, and a light beam from the active layer is emitted through the transparent substrate. Optical amplification element. 2. The planar optical amplifying device according to claim 1, wherein the optical amplifying function portion is adhered to the transparent substrate on one side of the n-type semiconductor layer; and on the opposite side of the active layer. A planar light amplification element, wherein the electrode for injecting holes into the p-type semiconductor layer is a divided electrode divided into a plurality of divided electrodes; 3. The planar optical amplifying device according to claim 2, wherein the active layer in the optical amplifying function portion includes an n-type semiconductor clad layer as the n-type semiconductor layer, and the p-type semiconductor layer. The optical amplification function part is adhered to a transparent substrate on the side of the n-type semiconductor cladding layer; the plurality of divided electrodes are
Conduction is carried out through a p-type cap layer provided on the p-type semiconductor multilayer mirror; and an electrode conducting to the n-type semiconductor cladding layer is connected to a wiring conductor provided on the surface of the transparent substrate. A surface-type optical amplifying element. 4. An active layer for generating excited carriers is a p-type.
A method for manufacturing a surface-type optical amplifying element having a light-amplifying function portion including a structure sandwiched between n-type semiconductor layers and emitting a light beam in a direction rising at a predetermined angle with respect to the surface of a supporting substrate; After constructing the light amplification function part on the construction substrate for constructing the light amplification function part; bonding the exposed surface side of the light amplification function part to another transparent substrate before removing the construction substrate A method of manufacturing the surface-type optical amplifying device, comprising a step of removing the construction substrate thereafter. 5. The method for manufacturing a planar optical amplifier according to claim 4, wherein the active layer and the n-type semiconductor layer are formed on the construction substrate in the order of the p-type semiconductor layer; The transparent substrate is adhered to the exposed surface side of the n-type semiconductor layer; a plurality of conductive surfaces are connected to the p-type semiconductor layer on the exposed surface of the p-type semiconductor layer by removing the construction substrate. Forming a split electrode; a method of manufacturing a surface-type optical amplifying element.