JP2003298183A - Compound semiconductor laser and compound semiconductor laser element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound semiconductor laser capable of oscillating at at least two different wavelengths and making equal all of the emission positions of the light having these different wavelengths, and a compound semiconductor laser element capable of taking out light having an arbitrary wavelength from among light having different wavelengths. <P>SOLUTION: The compound semiconductor laser is a compound semiconductor laser comprising a resonator having a two- or three-dimensional refractive index periodic structure and having at least two different oscillating wavelengths, and the refractive index periodic structure has at least two different repetitive periods. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound semiconductor laser capable of oscillating at least two different wavelengths, and a compound semiconductor laser device capable of extracting light of an arbitrary wavelength from light of different wavelengths. Regarding

[0002]

2. Description of the Related Art The structure of a semiconductor laser currently in use is a Fabry-Perot type in which a resonator is formed by using an element end as a reflection mirror, and a Bragg reflection (DBR) type in which a diffraction grating is engraved outside the active region. The distributed feedback (DFB) type in which a diffraction grating is cut along the optical guide layer is generally used, and these lasers are applied in a wide range of fields.

Further, in recent years, due to the application to a high-speed and large-capacity two-dimensional array light source for optical communication and the expectation for miniaturization of optical devices, a light emitting device called a surface emitting laser which emits light in a direction perpendicular to the substrate surface. Is attracting attention. Among them, a laser called a vertical cavity surface emitting semiconductor laser (VCSEL) is particularly promising and is under development.

In the Fabry-Perot type laser, the oscillation wavelength is determined by the distance between the element end faces, that is, the size of the element. In the DBR type laser and the DFB type laser, the oscillation wavelength is determined by the shape of the diffraction grating, specifically, the material forming the diffraction grating and the period of the diffraction grating. Although the oscillation wavelength determined in this way has a certain width, it can basically take only one value (however, one wavelength here includes so-called second harmonic, third harmonic, etc.). . This can be advantageous for the purpose of oscillating only at a single wavelength, but conversely, it can only oscillate at one certain wavelength, and a resonator corresponding to a plurality of oscillation wavelengths can be used. It means difficult. Such inconvenience
The same occurs in VCSEL.

The cause of this problem comes from the physical essence that only one oscillation wavelength can be selected because the structure of the resonator is one-dimensional in any of the above lasers. Therefore, when lasers of different emission wavelengths are required, it is necessary to prepare a plurality of laser elements that oscillate at the respective emission wavelengths and control each laser element independently. In this case, of course, there arises a problem that the cost increases in proportion to the number of elements. Furthermore, since the emission position of the laser light from each element is different, a complicated optical system and adjustment are required to match the laser light paths,
There is a problem that the cost is further increased.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a compound semiconductor laser capable of oscillating at least two or more different wavelengths and to make the emission positions of light of these different wavelengths all equal. It is an object of the present invention to provide a compound semiconductor laser device capable of extracting light having an arbitrary wavelength from lights having different wavelengths.

[0007]

As a result of earnest research in view of the above object, the present inventor uses a photonic crystal (an artificial multidimensional periodic structure composed of a plurality of media having different dielectric constants) as a resonator. In the compound semiconductor laser, it has been discovered that it is possible to oscillate at two or more different wavelengths by making the photonic crystal portion have a structure having at least two different periods, and the present invention has been made.

That is, the compound semiconductor laser of the present invention is a compound semiconductor laser provided with a resonator having a two-dimensional or three-dimensional refractive index periodic structure, having at least two different oscillation wavelengths, and The periodic structure is characterized by having at least two different repeating periods.

The refractive index periodic structure has at least one periodic structure selected from the group consisting of a sphere, a cube, a rectangular parallelepiped, a circular hole, a cylinder, a square hole, and a prism formed of a low refractive index medium in a high refractive index medium. Or at least one selected from the group consisting of a sphere, a cube, a rectangular parallelepiped, a circular hole, a cylinder, a square hole, and a prism formed of a high refractive index medium in a low refractive index medium. It is preferably a structurally formed structure. Further, the ratio of the dielectric constant of the high refractive index medium to the low refractive index medium is preferably 4 to 25. Further, it is preferable that at least one material forming the refractive index periodic structure is a gas containing at least one selected from the group consisting of nitrogen, hydrogen, argon, neon, and xenon.

The compound semiconductor preferably has at least two active layers which emit light of different wavelengths. At least one of the different wavelengths is 770nm-790nm
And at least one other wavelength is preferably 640 nm to 660 nm. Further, it is preferable that the positions of emitting light of different wavelengths are all the same regardless of the wavelength.

At least a part of the compound semiconductor is
It is preferably composed of a III-V compound semiconductor,
As a laser oscillation method, it is preferable to have a means for injecting a current into the light emitting region of the active layer.

The compound semiconductor laser device of the present invention is characterized in that a polarizer is provided on the light extraction surface of the compound semiconductor laser. The polarizer provided on the light extraction surface allows any one of the different wavelengths of light generated in the active layer.
It is possible to extract light of one wavelength.

[0013]

1 is a plan view of a compound semiconductor laser according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

As shown in FIG. 2, an n-type InGaP cladding layer 2 is formed on the first main surface of an n-type GaAs substrate 1, and an undoped AlGaAs separate confinement heterostructure (SCH) is formed on the n-type cladding layer 2. Layer 3, undoped AlGaAs / AlGaAs multiple quantum well (MQW) active layer 4, undoped AlGaAs SCH layer 5, undoped AlGaAs / AlGaAs MQW active layer 6, undoped AlGa
An As SCH layer 7, a p-type InGaP clad layer 8 and a p-type GaAs contact layer 9 are formed. A p-type front surface electrode 11 is partially formed on the p-type contact layer 9, and an n-type back surface electrode 10 is formed on the back surface of the substrate 1. Further, a wire 12 is bonded to the p-type electrode 11.

As the semiconductor constituting the compound semiconductor laser, a III-V compound semiconductor, a II-VI group compound semiconductor or the like can be appropriately used, but metal organic vapor phase epitaxy (MOCV
From the viewpoint of applying the D) method or the molecular beam epitaxy (MBE) method, at least a part of the compound semiconductor is a group III element (A
l, Ga, In, etc.) and V group elements (N, P, As, Sb, etc.)
It is preferably composed of a III-V compound semiconductor.

The substrate is not necessarily a GaAs substrate, and a substrate made of InP, sapphire or the like may be used depending on the oscillation wavelength.

The n-type cladding layer 2 and the p-type cladding layer 8 are
It is preferably formed of a high refractive index dielectric material.
As a material for forming the cladding layer, a III-V group compound semiconductor or the like can be used. As a specific example, InP, G
Examples include aAs, InGaAs, InGaAsP and the like.

The active layer may be formed of a single semiconductor material or a single or multiple quantum well structure. In the case of a multiple quantum well (MQW) structure, for example, the well layer is made of InGaAs, AlGaAs, etc., and the barrier layer is GaAs, Al.
It can be formed of GaAs or the like. When both the well layer and the barrier layer are made of AlGaAs (AlGaAs / AlGaAs), the composition ratio is set so that the band gap energy of AlGaAs of the barrier layer is larger than that of AlGaAs of the well layer. In a preferred embodiment of the present invention, the two active layers 4, 6 having an undoped multiple quantum well (MQW) structure have an undoped AlGa having a bandgap energy larger than that of the active layers.
It is formed by being sandwiched between As separate confinement heterostructure (SCH) layers 3, 5, and 7. By thus forming the double hetero structure, carriers can be concentrated in the active layer.

The compound semiconductor laser of the present invention has at least two or more different oscillation wavelengths. Since the wavelength of light generated in the active layer is defined by the band gap of the active layer, it is desirable to form the two active layers 4 and 6 from semiconductors having different band gaps and set the respective band gaps appropriately. It is possible to obtain light emission of two wavelengths. As a method for generating light of two or more different wavelengths in the active layer, there are a method of forming an active layer having a sufficiently broad emission spectrum and a method of forming a plurality of active layers emitting light of different wavelengths. Either method may be used, but the latter method is preferable from the viewpoint of ease of production. Of course, both methods may be used together.

The oscillation wavelength of the compound semiconductor laser is CD-R /
From the viewpoint of application to an optical drive that can be used as both an RW drive and a DVD drive, at least one wavelength is
In the range 0nm to 790nm, with at least one other wavelength
It is preferably in the range of 640 nm to 660 nm.

From the viewpoint of application to an optical device, the oscillation method preferably oscillates by injecting a current into the light emitting region of the active layer.

As shown in FIG. 1, a circular through hole is formed in the central portion of the p-type surface electrode 11 to expose the p-type contact layer 9. On the exposed p-type contact layer 9, rectangular lattices set at predetermined intervals in vertical and horizontal directions are formed by forming circular holes at respective lattice points. As shown in FIG. 2, the plurality of circular holes penetrate the compound semiconductor stacked body and reach the substrate 1. In addition, each circular hole is filled with air. In this way, the p-type cladding layer 8 is formed with a two-dimensional photonic crystal structure in which circular holes made of air are periodically arranged. The photonic crystal structure is not limited to two dimensions and may be three dimensions.

The photonic crystal is formed of a two-dimensional or three-dimensional periodic refractive index structure and acts as a resonator.
The light generated in the light emitting layer is diffracted by the refractive index periodic structure formed in the p-type cladding layer 8. When the wavelength of light coincides with a predetermined period of the refractive index periodic structure, the phase condition of light is defined at the wavelength corresponding to the period. The light whose phase is defined propagates to the active layer and promotes stimulated emission. The stimulated emission produces light having a defined wavelength and phase, which propagates to the refractive index periodic structure. In this way, amplification of light having a specific wavelength and phase is repeated.

The compound semiconductor laser of the present invention has a two-dimensional or three-dimensional refractive index periodic structure, and the refractive index periodic structure has at least two different repeating periods. By providing a plurality of different repetition periods, it is possible to respectively define the wavelength and phase of the light generated by the plurality of active layers. In the compound semiconductor laser shown in FIG. 1, two different repeating periods are formed by setting the vertical and horizontal intervals of the rectangular lattice to different intervals. By thus forming the photonic crystal portion with at least two different periodic structures, it is possible to oscillate at at least two different wavelengths.

As the material forming the two-dimensional or three-dimensional refractive index periodic structure, it is preferable to use a material having a large difference in refractive index from the p-type cladding layer 8. By making the difference in refractive index large, it is possible to confine light in a medium having a large refractive index. Furthermore, it is preferable to use a material having a dielectric constant ratio of the high refractive index medium to the low refractive index medium of 4 to 25. An effective combination as a resonator has a relative permittivity with respect to air (hereinafter simply referred to as “relative permittivity”) of 4 to
It is a combination of 25 semiconductors and a gas having a relative dielectric constant of about 1. The gas having a relative dielectric constant of about 1 is preferably a gas having poor reactivity with semiconductors such as nitrogen, hydrogen, argon, neon and xenon.

The refractive index periodic structure can be any structure, but a simple structure is preferable from the viewpoint of ease of manufacture. For example, a space such as a sphere, a cube, a rectangular parallelepiped, a circular hole, a cylinder, a square hole, or a prism in which a low refractive index medium (air, a gas having a refractive index almost the same as that of air, etc.) is enclosed in a high refractive index medium is periodic. Structure and low refractive index medium (air,
A structure in which a sphere, a cube, a rectangular parallelepiped, a circular hole, a cylinder, a square hole, a prism, etc., which are made of a high refractive index medium, are periodically arranged in a gas having a refractive index substantially the same as that of air) is preferable. At least 2
The refractive index periodic structure having three different repeating periods may be formed by different structures. The periodic array is not limited to the rectangular lattice, and may be a triangular lattice, a square lattice, a hexagonal lattice, or the like.

The calculation method of the photonic band gap in the photonic crystal is described, for example, in Hisae Inoue: Applied Physics 64, 19 (1995) “Two-dimensional photonic band crystal”. By using such a calculation method, a photonic crystal resonator corresponding to a desired oscillation wavelength can be designed.

The p-type front surface electrode 11 and the n-type back surface electrode 10 have good bonding characteristics, good ohmic characteristics with the lower layer,
It is preferably formed so as to satisfy the adhesiveness with the lower layer. For example, a laminated electrode including a metal layer and an oxide layer can be used. These metal layer and oxide layer can be formed by a known method. Further, the electrodes 10 and 11 may be subjected to heat treatment (alloying) for imparting ohmic properties.

FIG. 8 is a vertical cross-sectional view showing the layer structure of a compound semiconductor laser according to another embodiment of the present invention, and FIG. 9 is shown in FIG.
FIG.

The n-type InGaP clad layer 1 is formed on the n-type GaAs substrate 17.
8, undoped AlGaAs SCH layer 19, undoped AlGaAs / AlG
aAs MQW active layer 20, undoped AlGaAs SCH layer 21, undoped AlGaAs / AlGaAs MQW active layer 22, undoped AlGaAs S
A CH layer 23 and a p-type InGaP cladding layer 24 are formed.
On the surface of the p-type InGaP cladding layer 24, parallel grooves having a predetermined interval and a predetermined width are formed in a stripe shape.
Further, parallel prisms made of p-type InP having different intervals and widths from the grooves formed in the p-type clad layer 24 are formed orthogonal to the grooves. On top of that, a p-type InGaP cladding layer 24
Side-by-side prisms made of p-type InP having the same spacing and width as the grooves formed in are formed in parallel with the grooves formed in the p-type InGaP cladding layer 24. In this way, two types of parallel prisms having different intervals and different widths are alternately and orthogonally stacked, so that two types of orthogonal prisms made of orthogonal p-type InP (and prisms made of two types of orthogonal air). A three-dimensional photonic crystal is formed by repeating the lamination of 8) eight times. By thus forming two types of repeating periods, it is possible to oscillate at two different wavelengths.
The structure (shape, size, interval, etc.) of the repeating period, material, etc. can be appropriately set according to the desired oscillation wavelength and the like. The parts other than the photonic crystal are the same as those of the compound semiconductor laser shown in FIG.

FIG. 12 is a vertical sectional view showing the layer structure of a compound semiconductor laser according to still another embodiment of the present invention. n type G
On the aAs substrate 30, n-type AlGaInP clad layer 31, undoped A
lGaAs SCH layer 32, undoped AlGaAs / AlGaAs MQW active layer 3
3, undoped AlGaAs SCH layer 34, undoped InGaP / AlGa
InP MQW active layer 35, undoped AlGaAs SCH layer 36, p-type AlGa
An InP clad layer 37 and a p-type GaAs contact layer 38 are formed. In the clad layer 37, circular holes having a predetermined diameter are arranged at two different intervals in the vertical and horizontal directions at different intervals to form a two-dimensional photonic crystal structure. In the compound semiconductor laser of this aspect, since the contact layer 38 is formed on the circular hole forming the photonic crystal structure, the low refractive index medium or the high refractive index medium can be enclosed in the circular hole. The structure (shape, size, interval, etc.) of the repeating period, material, etc. can be appropriately set according to the desired oscillation wavelength and the like. The parts other than the photonic crystal are the same as those of the compound semiconductor laser shown in FIG.

The compound semiconductor laser can emit laser beams of different wavelengths from the same position, but the emission position can be changed for each wavelength depending on the application.

It is not necessary to oscillate all two or more oscillation wavelengths of the compound semiconductor laser at the same time, and it is sufficient to oscillate only light having a desired wavelength depending on the situation. The compound semiconductor laser can generate two or more lights having different wavelengths with different polarizations. Therefore, it is possible to select an oscillation wavelength by installing a polarizer on the emission surface of laser light and controlling the orientation of the polarizer.

As described above, light can be separated for each wavelength by using the polarizer or the like. In addition to this, by giving an optical path difference to light of one wavelength, it can be used as a light source for a time-resolved spectroscopic measurement method such as a pump probe method.

[0035]

The present invention will be described in more detail by the following examples, but the present invention is not limited thereto.

Example 1 A compound semiconductor laser having the structure shown in FIGS. 1 and 2 was manufactured by the following procedure.

On the n-type (Si-doped) GaAs substrate 1, MOCVD method is used.
N-type (Si-doped) InGaP clad layer 2, and
P Al_0.3Ga_0.7As SCH layer 3, undoped with emission wavelength of 700 nm
Al_{0. 3}Ga_0.7As / Al_0.1Ga_0.9As MQW active layer 4, undoped
Al_0.3Ga_0.7As SCH layer 5, undoped Al with emission wavelength of 680 nm
_0.3Ga_0.7As / Al_0.1Ga_0.9As MQW active layer 6, undoped Al
_0.3Ga_0.7As SCH layer 7, p-type (Zn-doped) InGaP cladding layer
8 and a p-type (Zn-doped) GaAs contact layer 9 are grown.
Let

A resist is applied to the surface of the grown crystal,
Circles with a diameter of 50 nm were drawn at each lattice point of a rectangular lattice with a vertical 190 nm interval and a horizontal 180 nm interval using an electron beam writer. Development is performed after drawing, and then the semiconductor immediately below the drawing area is removed by dry etching using a reactive ion beam etching (RIE) device. As shown in FIG.
A two-dimensional photonic crystal structure was obtained in which circular holes made of air having a relative dielectric constant of 1 were periodically arranged in the P-clad layer 8.

Next, n is formed on the back surface of the n-type (Si-doped) GaAs substrate 1.
The mold electrode 10 was formed. Furthermore, as shown in Fig. 1, p-type (Zn
A p-type electrode 11 was formed around the portion of the surface of the doped) GaAs contact layer 9 where a circular hole was formed.

When a wire 12 was bonded to the p-type electrode 11 of the obtained semiconductor laser and electricity was applied, an emission spectrum as shown in FIG. 3 was obtained. The emission spectrum on the long wavelength side in Fig. 3 is the emission from the MQW active layer oscillated by the photonic band corresponding to the period of 190 nm intervals, and the emission spectrum on the short wavelength side shows that the emission from the MQW active layer is 180 nm. It is oscillated by the photonic band corresponding to the period of nm interval.

When the polarized light was measured, the light on the long wavelength side was 19
It was found that light on the short wavelength side in the periodic direction with an interval of 0 nm is polarized in the periodic direction with an interval of 180 nm. This also indicates that the light emission on the long wavelength side is light corresponding to a period of 190 nm interval, and the light on the short wavelength side is light of 180 nm interval in the periodic direction.

Example 2 A compound semiconductor laser device having the structure shown in FIGS. 4 and 5 was manufactured by the following procedure.

Compound semiconductor laser 13 obtained in Example 1
A polarizer 14 was installed on the top of the to prepare a compound semiconductor laser device. Next, the gear 15 was attached to the polarizer 14, and the gear 16 was attached so as to be in contact with the gear 15. The polarizer 14 was rotated by moving the gear 16 back and forth to select polarized light that could pass through.

A current was injected into the obtained compound semiconductor laser device to oscillate. First, when the emission wavelength was measured with the gear 15 pulled, an emission spectrum as shown in FIG. 6 was obtained. Next, the gear 16 was pushed in so that the polarizer 14 rotated exactly 90 °, and the emission wavelength was measured. As a result, an emission spectrum as shown in FIG. 7 was obtained. It can be seen from FIGS. 6 and 7 that the oscillation wavelength can be selected by controlling the polarizer 14.

Example 3 A compound semiconductor laser having the structure shown in FIGS. 8 and 9 was manufactured by the following procedure.

On the n-type (Si-doped) GaAs substrate 17, the MOCVD method is used.
N-type (Si-doped) InGaP clad layer 18, Ando
P Al_0.3Ga_0.7As SCH layer 19, undoped with emission wavelength of 700 nm
Al_{0. 3}Ga_0.7As / Al_0.1Ga_0.9As MQW active layer 20, undoped
Al_0.3Ga_0.7As SCH layer 21, undoped Al with emission wavelength of 680 nm
_0.3Ga_0.7As / Al_0.1Ga_0.9As MQW active layer 22, undoped Al
_0.3Ga_0.7As SCH layer 23 and p-type (Zn-doped) InGaP cladding
The growth layer 24 was grown.

A resist is applied to the surface of the grown crystal,
An electron beam writer was used to write parallel stripes with a width of 190 nm at intervals of 190 nm on the entire surface. Development was performed after writing, and then the InGaP clad layer 24 immediately below the drawing portion was removed by dry etching to form parallel stripe-shaped grooves having a width of 190 nm and a depth of 190 nm. On top of that, a p-type (Z
n-doped) InP substrates were bonded together and polished, wet-etched, and dry-etched to a thickness of 180 nm. A thin p-type (Zn-doped) InP substrate is coated with a resist, and an electron beam writer and RIE are used to make a width of 1 nm at intervals of 180 nm.
Parallel stripe-shaped through grooves of 80 nm were formed on the entire InP substrate so as to be orthogonal to the grooves on the InGaP cladding layer 24.

Further, a stripe-shaped through groove was formed.
Another p-type (Zn-doped) InP substrate was bonded onto the p-type (Zn-doped) InP substrate, and the thickness was reduced to 190 nm. Next, similar to the above method, parallel stripe-shaped through-grooves having a width of 190 nm at intervals of 190 nm were formed on the entire InP substrate so as to be parallel to the grooves on the InGaP cladding layer 24. The above-mentioned bonding-groove formation process is repeated 8 times, and as shown in FIG. 8 and FIG.
A photonic crystal 25 was obtained in which parallel stripe-shaped through grooves of 0 nm were orthogonally laminated alternately and periodically. The photonic crystal 25 has a dielectric constant of 10.5 p in air with a dielectric constant of 1.
This is a three-dimensional photonic crystal structure in which prisms made of type (Zn-doped) InP are periodically arranged. Finally, a p-type (Zn-doped) InP substrate was attached to the surface and polished to form a p-type (Zn-doped) InP contact layer 26.

An n-type electrode 27 is formed on the back surface of the n-type (Si-doped) GaAs substrate 17 of the obtained laminated body, and p-type (Zn-doped) InP is formed.
A p-type electrode 28 was formed on the surface of the contact layer 26. p-type electrode
When a wire 29 was bonded to 28 and electricity was applied, an emission spectrum as shown in FIG. 10 was obtained from one end face of the laminate. An emission spectrum as shown in FIG. 11 was obtained from the other end surface orthogonal to that. It is shown that long-wavelength light is oscillating corresponding to a period of 190 nm interval, and short-wavelength light is oscillating in a period direction of 180 nm interval.

Example 4 A compound semiconductor laser having the structure shown in FIG. 12 was manufactured by the following procedure.

On the n-type (Si-doped) GaAs substrate 30, the MOCVD method is used.
N-type (Si-doped) (Al_0.7Ga _0.3)_0.49In_0.51P
Rad layer 31, undoped Al_0.3Ga_0.7As SCH layer 32, emission wave
Undoped Al with a length of 780 nm_0.3Ga_0.7As / Al_0.1Ga_0.9As MQW
Active layer 33, undoped Al_0.3Ga_0.7As SCH layer 34, emission wavelength
650 nm undoped In_0.5Ga_0.5P / (Al_0.5Ga_0.5)_{0.4 9}I
n_0.51P MQW active layer 35, undoped Al_0.3Ga_0.7As SCH layer 3
6, p-type (Zn-doped) (Al_0.7Ga_0.3)_0.49In_0.51P crush
Layer 37 was grown.

Then, in the same manner as in Example 1, a circular hole having a diameter of 50 nm is formed at each lattice point of a rectangular lattice having a vertical 205 nm interval and a horizontal 170 nm interval by using an electron beam drawing apparatus and RIE. A two-dimensional photonic crystal structure periodically arranged therein was obtained. Further, a Zn-doped GaAs substrate was laminated on the clad layer 37 having the two-dimensional photonic crystal formed therein in a hydrogen atmosphere to form a p-type (Zn-doped) contact layer 38. Thus, a two-dimensional photonic crystal structure in which circular holes filled with hydrogen having a relative permittivity of 1 were periodically arranged in the InGaP cladding layer 37 having a relative permittivity of 10.5 was obtained.

An n-type electrode on the back surface of an n-type (Si-doped) GaAs substrate
39 was formed, and a p-type electrode 40 was formed on the surface of the p-type (Zn-doped) GaAs contact layer 38. When a wire 41 was bonded to the p-type electrode 40 and electricity was applied, an emission spectrum as shown in FIG. 13 was obtained. The emission spectrum on the long wavelength side in Fig. 13 is the emission from the MQW active layer oscillated by the photonic band derived from the periodicity at 205 nm intervals, and the emission spectrum on the short wavelength side shows the emission from the MQW active layer. 170 n
It is oscillated by a photonic band corresponding to a period of m intervals.

[0054]

As described above, in the compound semiconductor laser of the present invention, since the photonic crystal portion having at least two different repetition periods is used as the resonator, it is possible to oscillate at at least two different wavelengths, Further, it is possible to make the emission positions of lights of different wavelengths all equal.

[Brief description of drawings]

FIG. 1 is a plan view showing a compound semiconductor laser according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an emission spectrum of a compound semiconductor laser according to an embodiment of the present invention.

FIG. 4 is a partial cross-sectional view showing a compound semiconductor laser device of the present invention.

FIG. 5 is a plan view showing a compound semiconductor laser device of the present invention.

FIG. 6 is an emission spectrum in a low wavelength region of the compound semiconductor laser device of the present invention.

FIG. 7 is an emission spectrum in a long wavelength region of the compound semiconductor laser device of the present invention.

FIG. 8 is a vertical sectional view showing a compound semiconductor laser according to another embodiment of the present invention.

9 is a sectional view taken along line BB of FIG.

FIG. 10 is an emission spectrum in a low wavelength region of a compound semiconductor laser according to another example of the present invention.

FIG. 11 is an emission spectrum in a long wavelength region of a compound semiconductor laser according to another example of the present invention.

FIG. 12 is a cross-sectional view showing a compound semiconductor laser according to still another embodiment of the present invention.

FIG. 13 is an emission spectrum of a compound semiconductor laser according to yet another example of the present invention.

[Explanation of symbols]

1, 17, 30 ... Substrate 2, 18 ... N-type clad layer 3, 5, 7, 19, 21, 23 ... SCH layer 4, 6, 20, 22 ... MQW layer 8, 24 ... p-type clad layer 9, 26 ... p-type contact layer 10, 27, 39 ... n-type electrode 11, 28, 40 ... P-type electrode 12 ... wire 14 ... Polarizer 15, 16 ... Gear 25 ... Photonic crystal 31 ... n-type clad layer 32, 34, 36 ... SCH layer 33, 35 ... MQW layer 37 ... p-type cladding layer 38 ... p-type contact layer

Claims (12)

[Claims] 1. A compound semiconductor laser comprising a resonator having a two-dimensional or three-dimensional refractive index periodic structure, wherein the compound semiconductor laser has at least two different oscillation wavelengths and the refractive index periodic structure is at least two different. A compound semiconductor laser having a repeating period. 2. The compound semiconductor laser according to claim 1, wherein the refractive index periodic structure includes a sphere, a cube, a rectangular parallelepiped, a circular hole, a cylinder, a square hole, and a low refractive index medium in a high refractive index medium. A compound semiconductor laser having a structure in which at least one selected from the group consisting of prisms is periodically formed. 3. The compound semiconductor laser according to claim 1, wherein the refractive index periodic structure is a sphere, a cube, a rectangular parallelepiped, a circular hole, a cylinder, a square hole, and a low refractive index medium which are made of a high refractive index medium. A compound semiconductor laser having a structure in which at least one selected from the group consisting of prisms is periodically formed. 4. The compound semiconductor laser according to claim 2 or 3, wherein the ratio of the dielectric constant of the high refractive index medium to the low refractive index medium is 4 to 25. 5. The compound semiconductor laser according to claim 1, wherein at least one material forming the refractive index periodic structure is selected from the group consisting of nitrogen, hydrogen, argon, neon, and xenon. At least 1
A compound semiconductor laser, which is a gas containing a seed. 6. A compound semiconductor laser according to claim 1, wherein the compound semiconductor laser has at least two active layers that emit light of different wavelengths. 7. The compound semiconductor laser according to claim 1, wherein the emission positions of the light having different wavelengths are all the same regardless of the wavelength. 8. The compound semiconductor laser according to claim 1, wherein at least one of the different wavelengths is used.
One wavelength is 770 nm to 790 nm, and the other at least one wavelength is 640 nm to 660 nm. 9. The compound semiconductor laser according to claim 1, wherein at least a part of the compound semiconductor is composed of a III-V group compound semiconductor. 10. The compound semiconductor laser according to claim 1, further comprising means for injecting a current into a light emitting region of the active layer. 11. A compound semiconductor laser device, comprising a polarizer on the light extraction surface of the compound semiconductor laser according to claim 1. 12. The compound semiconductor laser device according to claim 11, wherein light of any one wavelength is extracted from lights of different wavelengths generated in the active layer.