JP3163566B2 - Second harmonic generation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICATION Optical disc memory is currently revolutionizing the way data is stored. It gives so much information 4 1 /
This is because it can be stored on a 2-inch optical disk and read. The current application of optical discs is compact
It extends to the storage of digital information for use in disk players and computers. The present invention relates to a second harmonic generation device that can be used as a light source in the above-described optical disk memory, and further, a laser printer, holography, a laser knife, optical measurement, and the like.

[Conventional technology]

The cheapest laser element currently available is a GaAs laser diode. In such a semiconductor laser device, the oscillation wavelength of the laser can be adjusted by appropriately selecting the combination of the epitaxial layers of the material Al _x Ga _{1 -x} As or by appropriately selecting the operating temperature of the device. The wavelength region obtained so far is 780-840 nm. Laser power is increasing day by day and is currently on the order of 100mW.

Light having a half wavelength can be obtained by using the frequency of the output light of the laser diode. By using this, it is considered that the minimum spot diameter can be further reduced and the capacity of the optical disk memory can be increased.

The current frequency multiplication method uses an optically non-linear crystal. Such a nonlinear crystal can generate a second harmonic light or a third or higher harmonic light according to the intensity of incident light when light is incident under appropriate conditions and in an appropriate direction. appear.

Here, the intensity of the second harmonic is proportional to I ² × L. Here, I is the intensity of the incident primary light, and L is the length of the crystal where the phase of the I-order light and the phase of the second harmonic light are matched within the range of π / 2 radians. Therefore, to increase the intensity of the second harmonic light, either the intensity of the primary light or the phase matching length must be increased.

Recently, attempts have been made to increase the phase matching length by various methods. One is a method using an optical waveguide formed on a nonlinear substrate. In this method, phase matching is achieved between the guided mode and the radiation mode of the second harmonic generated in the nonlinear substrate. In this so-called Cherenkov method,
Using a laser diode as the primary light source, continuous light (CW) output up to 1 mW has been obtained.

[Problems to be solved by the invention]

Currently, the storage capacity of optical discs is
Limited by beam resolution. It is the wavelength of the laser beam that limits this resolution. Currently, the cheapest laser devices on the market are GaAs / AlGaAs laser diodes, but since the wavelength range of these laser devices is 780 to 860 nm, the minimum spot diameter of the beam obtained is only a factor times this wavelength. No.

On the other hand, if an inexpensive laser element that oscillates in the wavelength region of 400 nm, that is, in the blue region, can be manufactured, the storage capacity can be quadrupled.

However, it is difficult to cause the laser element itself to oscillate in the blue region, and it is necessary to use a second-harmonic substance made of a nonlinear crystal to obtain a wavelength in the 400 nm region, that is, light in the blue region as second-harmonic light. ing.

The currently developed second harmonic generation device uses the Cherenkov method as described above to obtain a large output with a long phase matching length.

However, in this method, the primary laser light must be focused on a fine optical waveguide, so that it is necessary to accurately adjust and assemble a number of parts, and a light source comprising this secondary harmonic generation device Since the output from is divergent, a lens that converges the output is also required. As a result, this type is bulky, unreliable and considerably more expensive.

Another method uses a non-linear, birefringent crystal, such as KTP (KTiOPO ₄ ). However, such a crystal is extremely expensive, and the crystal orientation must be strictly selected in order to match the phases. In order to obtain the second harmonic by this method, a strong 1
Next light is needed. As a result, this method is inevitably too expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inexpensive secondary harmonic generation device which can be miniaturized and can enhance reliability, and can be easily synchronized with the resonance condition of primary light.

[Means for solving the problem]

The second harmonic generation device according to claim (1) has a first harmonic generation device.
A compound semiconductor multi-layer laminated structure that constitutes a semiconductor laser that generates primary light by being laminated on the multilayer laminated reflecting mirror; and the compound semiconductor multilayer structure that is laminated on the compound semiconductor multilayer laminated structure and the first multilayer laminated reflecting mirror. 1
A second multi-layer laminated reflecting mirror constituting a Fabry-Perot resonator for the next light, and a second harmonic generating material laminated on the second multi-layer laminated reflecting mirror and receiving primary light from the semiconductor laser A second layer and a second multi-layer laminated reflecting mirror interposed between the second harmonic generating material layer and the second harmonic generating material layer with respect to primary light in the second harmonic generating material layer. A third multi-layer laminated reflecting mirror constituting a Fabry-Perot resonator.

The second harmonic generation device according to claim 2, wherein the compound semiconductor multilayer structure forming the semiconductor laser for generating the primary light, and first and second layers sequentially stacked on the compound semiconductor multilayer structure. A multi-layer laminated reflecting mirror, a second harmonic generating material layer laminated on the second multi-layer laminated reflecting mirror, into which primary light from the semiconductor laser is incident, and a second harmonic generating material layer laminated on the second harmonic generating material layer. And the first multilayer laminated reflecting mirror reflects the second harmonic light generated in the second harmonic generating material layer and transmits the first light, and the second multilayer laminated reflecting mirror comprises: The laminated reflecting mirror reflects the primary light, and the third multilayer reflecting mirror reflects the primary light and transmits the second harmonic.

[Action]

According to the configuration described in claim (1), the primary light is generated from the semiconductor laser having the compound semiconductor multilayer structure, and the primary light is stacked in the compound semiconductor multilayer structure.
When the primary light enters the second harmonic generation material layer, the second harmonic generation material layer generates the second harmonic light. At this time, the primary light in the second harmonic generation material layer resonates in the Fabry-Perot resonator to increase the light intensity, and the second harmonic in the second harmonic generation material layer Generation efficiency is increased,
The light intensity of the generated second harmonic light increases.

In particular, one of the pair of multilayer laminated reflecting mirrors is transparent to the second harmonic, and furthermore, the semiconductor multilayer laminated reflecting mirror and the Fabry / Multilayer reflecting mirror for the primary light are used.
The following effects can be obtained by using the dielectric multilayer laminated mirror constituting the Perot resonator. That is, although one of the multilayer laminated reflecting mirrors is made of a dielectric material, it is a mirror forming a Fabry-Perot resonator for the primary light. The intensity of light can be increased, and as a result, the intensity of second harmonic light can be increased. And furthermore, 2
Because the dielectric multilayer reflector is transparent to the second harmonic light, the second harmonic light is not absorbed in the dielectric multilayer mirror, and the second harmonic light can be efficiently extracted outside. It becomes possible.

Also, a Fabry-Perot resonator is formed for the compound semiconductor multilayer laminated structure constituting the semiconductor laser that generates the primary light, that is, the intensity of the primary light in the secondary harmonic generation material layer is reduced. In addition to the Fabry-Perot resonator that is configured to sandwich the second harmonic material layer to increase the height,
Since the Fabry-Perot resonator is also configured for the semiconductor laser that generates the primary light, the primary light intensity emitted from the semiconductor laser can be increased in the first place, and as a result, the intensity of the second harmonic light can be further increased. It becomes possible.

According to the configuration described in claim (2), a Fabry-Perot resonator that enhances the intensity of the primary light in the second harmonic material layer by the second multilayer laminated reflector and the third multilayer laminated mirror is provided. With this configuration, not only is the intensity of the primary light increased as in claim (1) but also the output of the second harmonic light to the outside is increased by providing the first multilayer laminated reflecting mirror. be able to.

That is, the second-harmonic light generated in the second-harmonic material layer is emitted not only in one direction but also in a direction 180 degrees opposite thereto, but half of the generated second-harmonic is 1 The process returns to the semiconductor laser that generates the next light. Since the second harmonic returned to the semiconductor laser is consumed in the active region of the semiconductor laser, half of the generated second harmonic is wasted. Therefore, if a first multilayer laminated reflecting mirror (reflecting the second harmonic light generated in the second harmonic generation material layer and transmitting the first light) is formed as described in claim (2), originally, Since the second harmonic returning to the semiconductor laser side is reflected again to the second harmonic generating material layer side and output to the outside, it is theoretically 2nd in comparison with the invention described in claim (1). The output of the second harmonic light to the outside can be doubled.

The configuration described in claim 1 provides the following two major advantages.

a A semiconductor laser that generates primary light, a pair of reflecting mirrors that constitute a Fabry-Perot resonator for the primary light, and a second harmonic generating material (nonlinear material) are separately formed and integrated. Instead of laminating a compound semiconductor multi-layer structure forming a semiconductor laser and a second harmonic generation material layer, a Fabry-Perot resonator is formed with at least the second harmonic generation material layer interposed therebetween. Since a pair of multi-layer laminated reflectors are stacked, one part
It has the function of generating the secondary light, the function of the Fabry-Perot resonator for the primary light, and the function of generating the second harmonic. A second harmonic generation device can be realized.

b. Since the length of the Fabry-Perot resonator can be reduced, the mode interval (free spectral range) of the resonance peak of the Fabry-Perot resonator can be increased. Also, since the resolution (resonance width) can be made sufficiently large,
The wavelength of the primary incident laser light (primary light) can be easily synchronized with the resonance conditions by adjusting the operating temperature.

The advantage of the configuration of claim (2) is the same as that of claim (1).

〔Example〕

Hereinafter, examples of a monolithic type second harmonic generation device including the above Fabry-Perot resonator will be described with reference to the drawings. Prior to the description of the embodiments, a second harmonic generation device which is a basis of the present invention will be described.

The second harmonic generation device which forms the basis of the present invention is a semiconductor multilayer laminated reflection mirror (wavelength selective reflection mirror) and a dielectric which constitute a Fabry-Perot resonator for the second harmonic generation material layer for primary light. It shows a structure sandwiched between a multilayer laminated reflecting mirror (wavelength selective reflecting mirror). In this foundation,
An external laser diode is used as an excitation source (primary light source), and can generate second harmonic light in both the transmission mode and the reflection mode.

The basis of this is a general configuration used in the embodiments.

The embodiment shows a configuration in which the configuration of the above-mentioned basic component and a surface emitting laser are monolithically combined to provide a semiconductor blue laser light source.

Second Harmonic Generation Device as a Base A second harmonic generation device as a base will be described with reference to FIGS. 1 to 3. FIG.

As shown in FIG. 1 (a), the second harmonic generation device on which this is based is formed by laminating a buffer layer 20 on a suitable substrate 10 and then forming a semiconductor multilayer laminated reflector (λ / 4 wavelength selective reflector). 30), a second harmonic generation material layer 40 composed of an optically nonlinear material, and a dielectric multilayer laminated reflecting mirror (λ / 4 wavelength selective reflecting mirror) 50 are sequentially grown to produce the second harmonic generation. The semiconductor multilayer laminated reflection mirror 30 and the dielectric multilayer laminated reflection mirror 50 are laminated with the material layer 40 interposed therebetween, and primary light is incident on the second harmonic generation material layer 40 from the outside. The mirror 30 and the dielectric multilayer reflecting mirror 50 constitute a Fabry-Perot resonator for primary light incident on the second harmonic generation material layer 40 from the outside.

The semiconductor multilayer reflective mirror 30 on the substrate 10 side is
Above, the refractive index at a wavelength λ in vacuum is n _A and the thickness is λ
/ 4n laminating low refractive index layer 31 of the _A, the wavelength of the vacuum thereon λ
The high refractive index layer 32 having a refractive index of n _G (n _G > n _A ) and a thickness of λ / 4n _G is laminated, and a low refractive index layer having a refractive index of n _A and a thickness of λ / 4n _A below 31 the refractive index of a thickness in n _G alternately laminated lambda / 4n high refractive index layer 32 of _G, a high refractive index layer 32 of the last refractive index thickness at n _G λ / 4n _G Laminated.

As the second harmonic generation material layer 40, among the II-VI group compound semiconductors or other compound semiconductors, those having optically nonlinear characteristics, for example, KTiOPO ₃ or the like are used. The refractive index at the wavelength λ of the second harmonic generation material layer 40 is n _S , and the thickness is a coherent length 2nλ / 4n _S [n is an integer]. Note that the thickness is (2n + 1) λ / 4n _S depending on the refractive index of the dielectric multilayer laminated reflecting mirror 50 laminated thereon.
And sometimes.

The dielectric multilayer laminated reflecting mirror 50 on the opposite side of the substrate 10 has a wavelength λ.
Thickness using a refractive index n _H is the high-refractive index layer 51 of lambda / 4n _H in,
Low refractive index layer having a refractive index of thickness at n _L is lambda / 4n _L at wavelength lambda
52 are alternately laminated, and the layer immediately above the second harmonic generation material layer 40 has a high refractive index of n _H and a thickness of λ / 4n _H when n _H > n _S. Becomes layer 51, and when n _H <n _S , the refractive index is
thickness using a n _L is the low refractive index lip 52 of lambda / 4n _L.

A specific example of the crystal layer structure in the above second harmonic generation device will be described. The present invention is not limited to this example, but is shown as one application example that can be realized by the current crystal growth technology. As the substrate 10, for example, GaAs is used.
This is because the technique of epitaxy of group crystals is well established. As the buffer layer 20, the same GaAs as the substrate 10 is laminated. Further, in the semiconductor multilayer laminated reflecting mirror 30, for example, an AlAs layer is used as the low refractive index layer 31, and an Al _x Ga _1-x As layer (for example, Al _0.3 Ga _0.7
As layer). This layer can be made of ZnS, Zn
It may be composed of Se, ZnSSe which is a mixed crystal thereof, or ZnS / ZnSe superlattice.

Numerous dielectrics can be applied to the dielectric multilayer laminated reflecting mirror 50, provided that it is transparent to the second harmonic light. For example, a combination of a SiO ₂ layer and a ZrO ₂ layer is one example.

In the second harmonic generation device having the above-described structure, the semiconductor multilayer reflecting mirror 30 and the dielectric multilayer reflecting mirror 50 constitute a Fabry-Perot resonator for primary incident light. When the output wavelength of the laser that causes the primary light to be incident on the secondary harmonic generation device is synchronized with the Fabry-Perot resonance condition, the intensity of the primary incident light has a secondary harmonic generation material layer 40 that is a nonlinear material. Intensity in place, resulting in higher second harmonic generation efficiency. That is, the second harmonic light having a high intensity is generated from the second harmonic generation material layer 40 and emitted to the outside through, for example, the dielectric multilayer laminated reflecting mirror 50.

FIG. 1 (b) shows the intensity distribution of the primary light in the secondary harmonic generation device of FIG. 1 (a), where the intensity of the primary light is high in the secondary harmonic generation material layer 40, It can be seen that the intensity of the primary light is low in the semiconductor multilayer reflective mirror 30 and the dielectric multilayer reflective mirror 50.

The underlying second-harmonic generation device is either a reflection-type or a transmission-type second-harmonic generation device depending on the transmittance of light at a desired wavelength to the substrate in relation to the laser as the primary light source. It can also be realized as a device.

FIG. 2 shows an example of a reflection type second harmonic generation device. 2, reference numeral 61 denotes a laser light source which comprises a laser diode and generates primary light, 62 denotes a lens, 63 denotes a lens, 64 denotes the second harmonic generation device shown in FIG.
Is a dichroic mirror (mirror coated with a dielectric material) that reflects primary light and transmits second harmonic light, and 66 is a lens.

In the above configuration, the primary light emitted from the laser light source 61 is converted into parallel light by a lens 62 and radiated to a dichroic mirror 65, reflected by the dichroic mirror 65 and narrowed by a lens 63 to generate a second harmonic. Light is incident on the device 64. As a result, a standing wave of the primary light rises in the second harmonic generation device 64, and a part of the second harmonic light generated by the standing wave travels to the substrate side, but the others are reflected and radiated to the outside. Is done. The second harmonic light radiated from the second harmonic generation device 64 to the outside is converted into parallel light by a lens 63 and radiated to a dichroic mirror 65, and a dichroic 6 mirror
The light passes through 65 and is stopped down by the lens 66. Meanwhile, 2
The primary light leaked from the second harmonic generation device 64 is reflected by the dichroic mirror 65 and emitted in a direction different from the second harmonic light, so that the primary light and the second harmonic light are separated.

FIG. 3 shows an example of a transmission type second harmonic generation device. In FIG. 3, reference numeral 71 denotes a laser light source which comprises a laser diode and generates primary light, and 72 denotes a lens.
Reference numeral 73 denotes a second harmonic generation device similar to that shown in FIG. 1, and includes a substrate 74a and an epitaxial layer 7 stacked on the substrate 74a.
4b, the epitaxial layer 74b constitutes a semiconductor multilayer laminated mirror, a second harmonic generation material layer, and a dielectric multilayer laminated mirror. In this example, the primary light transmitting portion of the substrate 74a is removed from the rear side by etching, and the substrate 74a is removed.
The primary light absorption by a is reduced, but this is not necessary if the primary light absorption is negligible.

Reference numerals 75 and 76 denote dichroic mirrors that reflect primary light and transmit second harmonic light, and reference numeral 77 denotes a lens.

In the above configuration, the primary light emitted from the laser light source 71 is stopped down by the lens 72 and
It is incident on 73. As a result, in the second harmonic generation device 73, a standing wave of the primary light rises as in the case of FIG. Radiated to In the case of this example, the second harmonic light that travels forward and is radiated to the outside is used. The second harmonic light emitted from the second harmonic generation device 73 is suitable for the dichroic mirror 75, is converted into parallel light by the lens 77, and is emitted through the dichroic mirror 76.

On the other hand, the primary light leaked from the second harmonic generation device 73 is reflected by the dichroic mirror 75 and returns to the second harmonic generation device 73. The primary light leaked from the dichroic mirror 75 is reflected by the dichroic mirror 76. The reflected light is emitted in a direction different from that of the second harmonic light, so that the separation of the primary light and the second harmonic light is completed.

In the above description, two dichroic mirrors 75, 76
Is used to improve the separation between the first-order light and the second-order harmonic light, and the dichroic mirrors 75 and 76 are used.
Only one of them may be provided.

The reflection-type and transmission-type second harmonic generation devices as described above have the following advantages as compared with ordinary waveguide-type second harmonic generation devices.

There is no need to align the primary light with the optical waveguide having fine dimensions.

Since the second harmonic generation material layer 40 only needs to exist in a minute space, the cost is low.

Since long-term stable integration with a vertical laser is possible, the cost is reduced and the number and size of components can be reduced.

In particular, in the reflection mode shown in FIG. 2, a material layer having an appropriate layer structure can be used as a second harmonic generation device without further processing.

Embodiment An embodiment will be described with reference to FIGS. 4 to 7. FIG.

This embodiment corresponds to claims (1) and (2).
As shown in the figure, a compound semiconductor multilayer laminated structure 88 constituting a surface reflection type semiconductor laser that generates primary light, and primary light from the semiconductor laser that is laminated on the compound semiconductor multilayer laminated structure 88 and enters The first harmonic generation material layer 83 and at least the second harmonic generation material layer 83
It has a dielectric multilayer reflective mirror 82 and a semiconductor multilayer reflective mirror 85 that constitute a Fabry-Perot resonator for the next light, and the above configuration is formed on a substrate 81 made of, for example, GaAs.

The dielectric multilayer laminated reflecting mirror 82 has a structure in which SiO ₂ layers and ZrO ₂ layers are alternately laminated, and is transparent to the second harmonic light,
Its thickness and the like are the same as those of the dielectric multilayer laminated reflecting mirror 50 shown in FIG.

The second harmonic generation material layer 83 is made of the same II-VI compound semiconductor as that shown in FIG.
It is about 0.5 to 1.0 μm.

The semiconductor multilayer reflecting mirror 85 has a semiconductor multilayer structure in which p-Al _0.10 Ga _0.90 As layers and p-Al _0.70 Ga _0.30 As layers are alternately stacked, and the thickness and the like are as shown in FIG. It is the same as the reflecting mirror 30.

The compound semiconductor multilayer laminated structure 88 is composed of a multilayer laminated structure of AlGaAs or a multilayer laminated structure of GaAs and AlGaAs. As an example, FIG. 4 shows an n-Al _0.30 Ga _0.70 As etch stop layer 88a and an n-Al _0.56 Ga _0.44 As cladding layer 88b and n-
The GaAs active layer 88c and the p-Al _0.33 Ga _0.67 As clad layer 88d constitute a surface emitting laser (SEL).

84 is a cap layer provided on the surface of the semiconductor multilayer laminated reflecting mirror 85 and is made of, for example, p ⁺ -GaAs. A buried layer 87 is made of, for example, n-GaAs. Reference numeral 89 denotes a buffer layer made of n-GaAs. 86a and 86b are metal electrodes, respectively.

In this embodiment, since the second harmonic generation material layer 83 and the compound semiconductor multilayer structure 88 constituting the surface emitting laser (SEL) are integrated, the number of parts is reduced, and the device is small and highly reliable. A second harmonic light source can be provided. Further, in this embodiment, since the dielectric multilayer laminated reflecting mirror 82 and the semiconductor multilayer laminated reflecting mirror 85 constituting the filter and the reflecting mirror are integrated, the efficiency of the second harmonic generation can be doubled, The intensity of the second harmonic light reflected through the body multilayer reflecting mirror 82 can be increased.

The most direct method for integrating the Fabry-Perot cavity and the surface emitting laser in order to increase the second harmonic generation efficiency is as shown in FIG. The second harmonic generation material layer 83 made of II-VI compound semiconductor is directly embedded in the semiconductor multilayer structure 88. This approach has already been proposed in Yokokawa et al. By using the same resonator cavity, the intensity of the primary light is reduced to the second harmonic generation material layer 83.
It is confirmed that the maximum is obtained at. This approach is made even more effective by using a dielectric multilayer reflector 82 and a semiconductor multilayer reflector 85 that have higher reflectivity than those used in ordinary lasers.
The reason is that in this case, what is important is to increase the intensity of the primary light in the cavity, not to increase the output power of the primary light. Dielectric multilayer laminated mirror
Since 82 transmits the second harmonic light and reflects the first light, increasing the second harmonic generation efficiency by this method has an advantage that the second harmonic light and the first light can be sorted in advance.

The above approach is limited by the intensity of the primary light in the laser cavity. Therefore, the laser
It is useful to increase the intensity of the primary light beyond the desired intensity for the cavity.

FIGS. 5 and 6 show, as a first modification, a structure in which the above object can be achieved by vertically integrating a Fabry-Perot resonator and a surface emitting laser.

FIG. 5 is a schematic diagram, and FIG. 6 is a detailed diagram. In these figures, 91 is a substrate made of GaAs, and 92 is a SiO ₂ layer.
A dielectric multilayer laminated reflecting mirror (dichroic mirror) having a structure in which _two layers of ZrO are alternately laminated. Reference numeral 93 denotes a second harmonic generation material layer (high light intensity second harmonic generation region) made of II-VI group compound semiconductor. ), 94 are n-Al _0.10 Ga _0.90 As layer and n-Al
_{This is} a semiconductor multilayer laminated reflecting mirror (dichroic mirror) having a structure in which _0.70 Ga _0.30 As layers are alternately laminated. Reference numeral 95 denotes a compound semiconductor multilayer laminated structure (laser active region) constituting a surface emitting laser, for example, n-Al _0.30 Ga _0.70 As
It comprises an etch stop layer 95a, an n-Al _0.56 Ga _0.44 As clad layer 95b, an n-GaAs active layer 95c, and a p-Al _0.33 Ga _0.67 As clad layer 95d. Reference _numeral 96 denotes a semiconductor multilayer laminated reflecting mirror (dichroic mirror) having a structure in which p-Al _0.10 Ga _0.90 As layers and p-Al _0.70 Ga _0.30 As layers are alternately laminated. 97 is a buried layer made of n-GaAs, 99 is a cap layer made of p ⁺ -GaAs, and 100 is a buffer layer made of n-GaAs.

 98a and 98b are metal electrodes, respectively.

4 is different from the structure of FIG.
Since the semiconductor multi-layer stacked reflecting mirror 94 is provided between the semiconductor multi-layer stacked structure 95 and the compound semiconductor multi-layer stacked structure 95, other structures are the same as those in FIG.

In the second harmonic generation device having the above-described structure, the n-type semiconductor multilayer reflective mirror 94 and the p-type semiconductor multilayer reflective mirror 96 correspond to the compound semiconductor multilayer laminated structure 95 constituting the GaAs laser diode. The primary light acts as a laser cavity and resonates between the semiconductor multilayer reflecting mirrors 94 and 96 as shown by an arrow A in FIG. 5, and a laser light that becomes primary light is obtained from this laser structure. The primary light is incident on the second harmonic generation material layer 93 made of a II-VI compound semiconductor. Here, the primary light is formed by a cavity formed by an n-type semiconductor multilayer reflecting mirror 94 and a dielectric multilayer reflecting mirror 92. The secondary light resonates again as indicated by the arrow B, the intensity of the primary light is increased in the secondary harmonic generation material layer 93, and the secondary harmonic light generated in the secondary harmonic generation material layer 93 is converted into a dielectric multilayer. The laminated reflecting mirror 92 is suitably emitted to the outside as shown by the arrow C.

Furthermore, by using a dielectric multilayer laminated mirror that reflects and returns the second harmonic light that would otherwise be consumed in the active region of the surface emitting laser (compound semiconductor multilayer laminated structure), Can be doubled. Such a dielectric multilayer laminated reflecting mirror that prevents and returns the incidence of the second harmonic light into the laser active region is configured to be transparent to the primary light and to reflect the second harmonic light and to be reflected. The returned second harmonic light must be placed in a position such that it is in phase with the original output light. FIG. 7 shows a second modification of the second harmonic generation device to which such a dielectric multilayer laminated reflecting mirror is added. In FIG. 7, reference numeral 101 denotes a dielectric multilayer laminated reflecting mirror that reflects primary light and is transparent to secondary harmonic light, 102 denotes a secondary harmonic generation material layer, and 103 denotes a dielectric multilayer that reflects primary light. A multilayer reflector, 104 is a dielectric multilayer reflector reflecting second harmonic light and transparent to primary light, 105 is a laser diode active region, 106 is a laminated structure of electrodes, insulators, dielectrics, etc. , 107 are substrates.

As described above, when the structure in which the dielectric multilayer laminated reflecting mirror 104 is provided is used, the second harmonic light emitted from the second harmonic generating substance layer 102 in the direction of the dielectric multilayer laminated reflecting mirror 101 as shown by the arrow D Is radiated to the outside through the dielectric multilayer laminated reflecting mirror 101. The second harmonic light emitted from the second harmonic generation material layer 102 in the direction of the dielectric multilayer reflective mirror 103 as shown by the arrow E is reflected by the dielectric multilayer reflective mirror 104, and As a result, the direction is reversed and the light is radiated to the outside through the dielectric multilayer laminated reflecting mirror 101, and arrows D and F
Are in phase with each other.

〔The invention's effect〕

According to the second harmonic generation device of the present invention, the following effects can be obtained.

(1) A single component can have multiple functions, and can be miniaturized and improved in reliability.
It can be manufactured at lower cost.

(2) By using a substrate having a macroscopic size as a growth substrate, a relatively thin second harmonic generating material layer can be deposited in a well-controlled state, and as a result, the layer thickness of the coherent length can be reproduced. It can be obtained well.

(3) The spacing between the resonances of the Fabry-Perot resonator, that is, the wavelength spectrum region between one resonance and the next resonance, and the resonance width can be made sufficiently large, so that the wavelength of the primary incident laser light controls the operating temperature. By doing so, it is possible to easily synchronize with the resonance conditions.

[Brief description of the drawings]

FIG. 1 (a) is a cross-sectional view showing the structure of a second harmonic generation device on which the present invention is based, and FIG. 1 (b) is the light intensity in the second harmonic generation device of FIG. 1 (a). FIG. 2 is a schematic diagram showing a structure of a reflection type second harmonic generation device using the device of FIG. 1, and FIG. 3 is a structure of a transmission type second harmonic generation device similarly. FIG. 4 is a sectional view showing the structure of an embodiment of the second harmonic generation device of the present invention, FIG. 5 is a schematic view showing a first modification of the embodiment, and FIG. FIG. 7 is a sectional view showing a second modification of the embodiment. 30 ... multilayer semiconductor multilayer reflector, 40 ... second harmonic generation material layer, 50: multilayer dielectric multilayer reflector, 82 ... multilayer dielectric mirror, 83 ... second harmonic generation material layer , 85 …… Semiconductor multilayer laminated reflector, 88 …… Compound semiconductor multilayer laminated structure,
92: dielectric multilayer laminated reflector, 93: second harmonic generation material layer, 94: semiconductor multilayer laminated mirror, 95: compound semiconductor multilayer laminated structure, 96: semiconductor multilayer laminated reflector, 101 ...
... Dielectric multilayer laminated reflector, 102 ... Second harmonic generation material layer, 103 ... Dielectric multilayer laminated reflector, 104 ... Dielectric multilayer laminated reflector, 105 ... Compound semiconductor multilayer laminated structure

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadashi Narusawa 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-63-280484 (JP, A) JP-A-61- 18933 (JP, a) JP Akira 64-35423 (JP, a) spring 1990 37th Japan Society of applied physics relationship Union Lecture Preprint 28p-F-13 (58) investigated the field (Int.Cl. ⁷ , DB name) G02F 1/37

Claims (2)

(57) [Claims] 1. A compound semiconductor multilayer laminated structure which is laminated on a first multilayer laminated reflecting mirror and constitutes a semiconductor laser for generating primary light; and said first multilayer laminated reflecting mirror laminated on said compound semiconductor multilayer laminated structure. A second multi-layer laminated mirror that constitutes a Fabry-Perot resonator with respect to the primary light with the compound semiconductor multi-layer structure interposed therebetween; and a first laser from the semiconductor laser laminated on the second multi-layer laminated mirror. A second harmonic generation material layer on which secondary light is incident, and the second harmonic with the second multi-layer laminated reflecting mirror interposed between the second harmonic generation material layer and the second harmonic generation material layer. A second harmonic generation device comprising: a third multilayer laminated reflecting mirror that constitutes a Fabry-Perot resonator for primary light in a generation material layer. 2. A compound semiconductor multilayer laminated structure constituting a semiconductor laser for generating primary light, first and second multilayer laminated reflecting mirrors sequentially laminated on said compound semiconductor multilayer laminated structure, and said second laminated semiconductor mirror. A second harmonic generating material layer laminated on the multilayer laminated reflecting mirror and receiving primary light from the semiconductor laser, and a third multilayer laminated reflecting mirror laminated on the second harmonic generating material layer; The first multilayer laminated reflecting mirror reflects the second harmonic light generated in the second harmonic generating material layer and transmits the primary light, and the second multilayer laminated reflecting mirror reflects the primary light. A second harmonic generation device, wherein the third multilayer laminated reflecting mirror reflects the primary light and transmits the secondary harmonic.