JP2751656B2 - Surface-emitting type optical second harmonic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, and more particularly to an optical second harmonic generation device.

[0002]

2. Description of the Related Art It is difficult to obtain blue light emission from a semiconductor, and attempts have been made to emit blue light by generation of an optical second harmonic. Using a semiconductor as a nonlinear material is highly compatible with using a semiconductor laser as an excitation light source (Journal of Crystal Grouse [Journal
of Crystal Growth] Vol. 101, No. 55
0, 1990).

[0003]

However, it is extremely difficult to form a semiconductor laser and an optical second harmonic element on the same substrate, and the semiconductor laser and the second harmonic element have not been put to practical use.

[0004]

In order to solve the above-mentioned problems, the present invention provides a method of forming a first .omega. Film comprising a multilayer film of a III-V compound semiconductor material grown on a semiconductor substrate.
A reflective film and an angular frequency ω of a III-V compound semiconductor,
An active layer that emits light having a wavelength of λ (ω), and a light that is made of a II-VI group semiconductor material that has second-order nonlinear optical characteristics grown on the active layer and transmits light having an angular frequency of 2ω. A second harmonic generation region, a second ω reflection film made of a semiconductor or dielectric material multilayer film , the active layer and the optical second harmonic
Group II-VI semiconductor material multilayers grown between the source region
A 2ω reflection film made of a film , wherein the layer structure of the optical second harmonic generation region is formed of at least one layer having a layer thickness that is an integral fraction of the coherent length of the ω light and the 2ω light. The second ω reflection film reflects ω light and 2ω
While transmitting light , the 2ω reflection film transmits ω light.
It is a surface-emitting type element characterized by reflecting 2ω light .

[0005]

The light having the angular frequency ω and the wavelength λ (ω) emitted from the active layer is reflected by the first ω reflection film and the second ω reflection film,
A standing wave is generated in the region of the active layer to cause laser oscillation. The laser-oscillated light is converted into light having an angular frequency of 2ω in the optical second harmonic generation region. The conversion efficiency to 2ω is determined by the intensity of the ω light and the phase matching condition. Since the optical second harmonic generation region is in the resonator formed by the first ω reflection film and the second ω reflection film, the intensity of the ω light is 100 times or more the intensity outside the resonator, The conversion efficiency becomes very high. Further, the wave numbers of the ω light and the 2ω light in the optical second harmonic generation region are represented by k (ω) and k (2
ω), the coherent length L _c is L _c = 2π / {k (2ω) −2k (ω)}, and the period d = L _c / n where n is an integer in the multilayer structure of the harmonic generation region. By introducing a structure, phase matching can be achieved. Further if less coherent length L _c with a layer thickness is a single layer of the second harmonic light generating region, there is no problem of phase mismatching. By introducing such a layer structure, conversion from ω to 2ω light can be performed with high efficiency without a problem of phase mismatch. Also, the optical second harmonic generation region is a high quality film formed by crystal growth,
Low loss for 2ω light.

[0006] Second omega reflection film reflects only omega, to Toru <br/> over the 2 [omega, the conversion efficiency from omega to 2 [omega can be increased to nearly 100%.

The 2ω reflection film reflects the 2ω light generated in the second harmonic generation region and traveling toward the substrate, so that the absorption of the 2ω light in the active layer region is reduced, and the 2ω light is extracted to the outside by 2ω. Double it.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an example of the basic configuration of the present invention . P-type GaAs (67.2 nm thick), AlA on a semiconductor substrate 1 made of (0,1, -1) -plane P-type GaAs
s (thickness: 80 nm) first ω reflection film 2 composed of 24 periods,
The first spacer layer 3 made of P-type Al _0.5 Ga _0.5 As (having a thickness of 117 nm) and the P-type Al _0.2 Ga _0.8 As (having a thickness of 20 nm)
nm), the first optical confinement layer 4, In _0.2 Ga _0.8 A
active layer 5 of s (10 nm thick), n-type Al _0.2 G
a _0.8 As (20 nm thick) second optical confinement layer 6, n-type Al _0.5 Ga _0.5 As (117 nm thick) second spacer layer 7, n-type ZnSe (1 μm thick)
/ ZnS _0.2 Se _0.8 (thickness: 1 μm) Two-cycle optical second harmonic generation region 8, n-type ZnSe (thickness: 100 n
m) / ZnS _0.2 Se _0.8 (thickness: 102 nm) The second ω reflection film 9 composed of five periods is crystal-grown by a molecular beam epitaxy method, and is then etched into a column having a diameter of 2 μm by dry etching, and then P is deposited by vacuum evaporation. Electrode 1
0, n electrode 11 was formed.

The lattice constants of GaAs and ZnSe are almost equal, and a good crystal can be obtained. ZnSe, ZnSSe 2
Since the next non-linear susceptibility is large, the conversion efficiency from ω to 2ω light is high. When the semiconductor substrate 1 is in the (0,1, -1) plane and the electric field of the ω light is in the [1,1,1] direction parallel to the substrate surface, the electric field of 2ω is also in the [1,1,1] direction. Becomes
Propagation proceeds in the [0,1, -1] direction.

Light emission (angular frequency ω) from the active layer 5 is λ (ω ₀ ) = 1 μm at a wavelength in a vacuum. The first ω reflection film 2 and the second ω reflection film 9 are multilayer films having a thickness of λ (ω) / 4 with respect to ω light, and the reflectivity of ω light is 99.9.
% Or more. In this structure, the second ω reflection film 9 transmits 2ω light because it is transparent to 2ω light.

The ω light emitted from the active layer 5 by the current injection is reflected by the first ω reflection film 2 and the second ω reflection film 9 and oscillates by laser. The laser-oscillated ω light is converted into 2ω light in the optical second harmonic generation region 8. Coherent length L in ZnSe
_c is Is represented by Where k (ω), k (2ω) and n
(Ω) and n (2ω) are the wave number and the refractive index for the ω light and the 2ω light. n (ω) = 2.48 , n (2ω) = 2.73
Therefore, L _c = 2 μm. The optical second harmonic generation region 8 has a period of 2 μm and is phase-matched.

Since the intensity of the ω light in the optical second harmonic generation region 8 is strongly phase-matched, the conversion efficiency is 30% and the wavelength is 50%.
3 mW of 0 nm blue light was obtained.

FIG. 2 is a sectional view showing an embodiment of the present invention . On a semiconductor substrate 12 made of (0,1, -1) -plane n-type GaAs, n-type GaAs (67.2 nm thick), A
The first ω reflection film 13 composed of 24 cycles of 1As (80 nm thick), the first spacer layer 14 composed of n-type Al _0.5 Ga _0.5 As (117 nm thick), and the n-type Al _0.2 Ga _0.8 As
(Thickness: 20 nm), the first optical confinement layer 15, In
_An active layer 16 made of _0.2 Ga _0.8 As (10 nm thick);
A second optical confinement layer 17 made of P-type Al _0.2 Ga _0.8 As (thickness: 20 nm) and a P-type Al _0.5 Ga _0.5 As (thickness: 11 nm)
7 nm), a 2ω reflection film 19 having two periods of ZnSe (thickness 46 nm) / ZnS _0.2 Se _0.8 (thickness 46 nm), and an optical second harmonic generation region made of ZnSe (thickness 1 μm). 20 is crystal-grown by molecular beam epitaxy, then etched into a cylindrical shape having a diameter of 2 μm by dry etching, then n-electrode 21 and P-electrode 22 are formed by vacuum evaporation, and λ of amorphous Si / SiO ₂ is formed by sputtering evaporation. A second ω reflection film 23 composed of (2ω) / 4 layers was formed. Coherent length L
_In the optical second harmonic generation region 20 where _c = 2 μm and the thickness is half of the coherent length L _c , phase mismatch does not matter.

Of the light converted to 2ω in the optical second harmonic generation region 20, the light traveling downward from the substrate is λ
The light is reflected by the 2ω reflection film 19 serving as a (2ω) / 4 plate, and is taken out from the upper surface. As a result, a double output is obtained. The light of ω emitted from the active layer 16 passes through the 2ω reflection film 19, and the first ω reflection film 13 and the second ω reflection film 2
3 and is not output to the outside.
Converted to light. The obtained 2ω light has a wavelength of 500 nm ,
The conversion efficiency was 50% , and the output was 5 mW.

In this embodiment , ZnSe / ZnSSe is used as the II- VI group compound semiconductor material. However, the present invention is not limited to this, and another material system such as a ZnSSe superlattice or ZnTe may be used.

In the above-described embodiment, an AlGaInAs-based material is used as the III-V group compound semiconductor material. However, the material is not limited to this, and another material such as an InGaAsP-based material may be used.

[0017]

As described above, according to the present invention, an ultra-compact optical second harmonic generation device integrated with a semiconductor laser can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a basic configuration example of the present invention .

FIG. 2 is a cross-sectional view of one embodiment of the present invention .

[Explanation of symbols]

 Reference Signs List 1,12 Semiconductor substrate 2,13 First ω reflection film 3,14 First spacer layer 4,15 First light confinement layer 5,16 Active layer 6,17 Second light confinement layer 7,18 Second spacer layer 8, Reference Signs List 20 optical second harmonic generation region 9,23 second ω reflection film 10,22 P electrode 11,21 n electrode 19 2ω reflection film

Continuation of front page (56) References JP-A-63-280484 (JP, A) JP-A-2-281243 (JP, A) JP-A-4-14024 (JP, A) JP-A-4-307524 (JP) , A) Vacuum 33-11! (1990) P.A. 867-873 ELECTRON. LETT. 25-20! (1989) p. 1377-1378 Applied physics 56-12! (1987) P.A. 1625 -1629 (58) Fields investigated (Int. Cl. ⁶ , DB name) H01S 3/18 G02F 1/37

Claims (1)

(57) [Claims] A first ω reflection film comprising a multilayer film of a group III-V compound semiconductor material grown on a semiconductor substrate;
An active layer made of a group V compound semiconductor that emits light having an angular frequency ω and a wavelength λ (ω); and a second-order nonlinear optical characteristic that is crystal-grown on the active layer and transmits light having an angular frequency of 2ω. Between the active layer and the optical second harmonic generation region, and the second ω reflection film composed of a semiconductor or dielectric material multilayer film.
Composed of II-VI group semiconductor material multi-layered film
A reflective film , wherein the layer structure of the optical second harmonic generation region is a periodic structure including at least one layer having a thickness equal to an integer fraction of the coherent length of the ω light and the 2ω light. The second ω reflection film reflects ω light and transmits 2ω light
At the same time, the 2ω reflection film transmits ω light and reflects 2ω light.
A surface-emitting type optical second harmonic element.