JPH0414024A - Secondary higher harmonic generation device - Google Patents

Abstract

PURPOSE:To provide one component with plural functions and to obtain the small-sized, highly reliable device by providing multi-layered laminate reflecting mirrors which constitute Fabri-P'erot resonator across a secondary higher harmonic generating material layer. CONSTITUTION:The semiconductor multi-layered laminate reflecting mirror 30 and dielectric multi-layered laminate reflecting layer 50 whcih constitute the Fabri-P'erot resonator to primary light are provided across the secondary higher harmonic generating material layer 40. The primary light is made incident on the secondary higher harmonic generating material layer 40 to generate a secondary higher harmonic. At this time, the primary light in to increase the light intensity, and the generation efficiency of the secondary higher harmonic in the secondary higher harmonic generating material layer 40 is increased to increase the light intensity. Therefore, one component has a resonating function to the primary light and a secondary higher harmonic generating function and the need for assembly adjusting operation is eliminated to obtain the small- sized, inexpensive device.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) Optical disk memory is currently revolutionizing the way data is stored. Current applications of optical discs extend to the storage of digital information used in compact disc players and computers. This invention relates to a second harmonic generation device that can be used as a light source for holography, laser scalpel, optical measurement, etc.

[Traditional techniques]

The cheapest laser element currently available is the 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 Evita core layer of the material system AlzGal-XAS and by appropriately selecting the operating temperature of the device. can. The wavelength range obtained so far is 780 to 840 nm.

Laser output is increasing day by day, and currently 100m
This is W's order.

By multiplying the frequency of the output light from a laser diode, it is possible to obtain light with half the wavelength. By using this, you can further reduce the minimum spot diameter and
It is thought that the memory capacity can be increased.

Current frequency multiplication methods use optically nonlinear crystals. Such a nonlinear crystal emits second-order harmonic light and third-order or higher harmonic light according to the intensity of the incident light under appropriate conditions and when light is incident from an appropriate direction. Occur.

Here, the intensity of the second harmonic is proportional to RXL. However, ■ is the intensity of the incident primary light, and L is the phase of the primary light and the
This is the length of the crystal in which the phase of harmonic light is matched within the range of π/2 radians.

Therefore, in order to increase the intensity of the second harmonic light, 1
Either the intensity of the secondary light or the phase matching length must be increased.

Recently, attempts have been made to increase the phase matching length using various methods. One method is to use an optical waveguide built into a nonlinear substrate. In this method, phase matching is achieved between the waveguide mode and the radiation mode of the second harmonic generated in the nonlinear substrate.9 In this so-called Cerenkov method, 1
Using a laser diode as the secondary light source, continuous light (CW) output up to 1 mW has been obtained.

[Problem to be solved by the invention]

The storage capacity of optical disks is currently limited by the resolution of the laser beam. What limits this resolution is the wavelength of the laser beam. The cheapest laser element currently on the market is GaAs/
AIGaAs laser diodes, the wavelength range of these laser elements is from 780 to 860
nm, the minimum spot diameter of the beam obtained is only a factor times this wavelength.

On the other hand, if an inexpensive laser element that oscillates at a wavelength in the 400 nm region, that is, in the blue region, could be made, the storage capacity could be increased four times.

However, it is difficult to make the laser element itself oscillate in the blue region, and by using a second harmonic generating material made of a nonlinear crystal, it is possible to generate a wavelength of 400 nm iJ, that is, light in the blue region, as second harmonic light. I'm trying to get it.

Currently developed second-order harmonic generation devices use the Cerenkov method as described above and are attempting to obtain a large output with a long phase matching length.

However, with this method, the primary laser beam must be focused onto a fine optical waveguide, so it is necessary to accurately adjust and assemble a number of parts, and the light source is made up of this second harmonic generation device. Since the output from the sensor is diverging, a lens is also required to converge the output. As a result, this type is large, has low reliability, and is considerably expensive.

Another method uses crystals called KTP (KTiOPO4
), a nonlinear and birefringent crystal is used. However, such crystals are extremely expensive;
In order to match the phase, the crystal orientation must be precisely selected. Furthermore, in order to obtain second harmonics with this method, strong first order light is required. As a result, this method is also inevitably quite expensive.

An object of the present invention is to provide a secondary harmonic generation device that can be miniaturized, has high reliability, can be synchronized to the resonance conditions of primary light, and is inexpensive. .

[Means to solve the problem]

The second harmonic generation device according to claim (1) includes a second harmonic generation material layer and a Fabry-Perot resonator for primary light, which is stacked with the second harmonic generation material layer sandwiched therebetween. and a plurality of multilayer laminated reflecting mirrors.

The second harmonic generation device according to claim (2) includes a compound semiconductor multilayer stacked structure constituting a semiconductor laser that generates the first order light, and a compound semiconductor multilayer stacked structure that is stacked on the compound semiconductor multilayer stack structure to generate the first order light from the semiconductor laser. a second harmonic generation material layer into which light is incident; and a plurality of multilayer laminated reflectors that are laminated with at least the second harmonic generation material layer sandwiched therebetween to form a Fabry-Bello resonator for the first order light. It is equipped with

The second harmonic generation device according to claim (3) is characterized in that a groove formed on one surface of the convex strip made of a second harmonic generation material contains a light wave having a refractive index of the same wavelength as that of the second harmonic generation IjfyJ material. an optical waveguide having a structure in which a material with a high refractive index is embedded, and a plurality of multilayer laminated reflecting mirrors laminated on both end surfaces of the optical waveguide to constitute a Fabry-Bello resonator for the primary light. We are prepared.

[For production]

According to the structure described in claim 11, when the first-order light enters the second-order harmonic generation material layer, the second-order harmonic generation material layer
Generates harmonic light. At this time, the first-order light in the second-order harmonic generation material layer resonates within the Fabry-Perot resonator and the light intensity is increased, and the second-order light in the second-order harmonic generation material layer The generation efficiency is increased, and the light intensity of the generated second harmonic light is increased.

According to the configuration described in claim (2), primary light is generated from a semiconductor laser configured with a compound semiconductor multilayer stacked structure,
When the first-order light enters a second-order harmonic generation material layer laminated in a compound semiconductor multilayer structure, the second-order harmonic generation material layer generates second-order harmonic light. At this time, the first-order light in the second-order harmonic generation material layer resonates within the Fabry-Perot resonator and the light intensity is increased, and the second-order light in the second-order harmonic generation material layer resonates within the Fabry-Perot resonator. The wave generation efficiency is increased, and the light intensity of the generated second harmonic light is increased.

According to the configuration described in claim (3), the groove formed on one surface of the convex strip made of the second harmonic generating material has a refractive index higher than that of the second harmonic generating material for light waves of the same wavelength. In an optical waveguide that has a structure in which a refractive index material is embedded, when first-order light enters a portion of the high-refractive-index material, the first-order light passes through the high-refractive-index material and generates second harmonics based on this first-order light. Second harmonic light is generated from the generating substance. At this time, the first-order light in the high refractive index material resonates within the Fabry-Perot resonator, increasing the light intensity, and increasing the second-order harmonic generation efficiency in the second-order harmonic generation material. The light intensity of the generated second harmonic light increases.

The configurations described in each of the above claims (1) provide the following two major advantages.

■a Instead of separately creating a plurality of reflecting mirrors and a second-order harmonic generating material (nonlinear material) that constitute a Fabry-Bello resonator for the first-order light and combining them integrally, at least the second-order Harmonic generation @IJ Since multiple multilayer laminated reflectors that make up the Fabry-Bello resonator are stacked with the IJ quality layer sandwiched between them, one component can function as a Fabry-Bello resonator for first-order light and for second-order harmonics. It can be equipped with a wave generation function, and requires no assembly or adjustment work.
A small and highly reliable second harmonic generation device can be realized.

(b) Since the resonator length of the Fabry-Bello resonator can be made small, the mode spacing (free spectral region) of the resonance peak of the Fabry-Bello resonator can be made wide. In addition, since the resolution (resonant radiation) can be sufficiently large, 1
The wavelength of the next incident laser light (primary light) can be conveniently synchronized to the resonance conditions by adjusting the operating temperature.

Further, the configuration described in 2) in each of the above claims provides the following two major advantages.

■a A semiconductor laser that generates the first-order light, multiple reflecting mirrors that constitute a Fabry-Bello resonator for the first-order light, and a second-order harmonic generating material (nonlinear material) are created individually and then integrated. Instead of combining the compound semiconductor multilayer structure that constitutes the semiconductor laser and the second harmonic emission it#
In addition to laminating the yJ material layer, multiple multilayer laminated reflectors constituting the Fabry-Bello resonator are laminated with at least a second harmonic generation material layer sandwiched between them, so a single component generates primary light. Fabry function and primary light
It is possible to provide a bellows resonator function and a second harmonic generation function, and there is no need for assembly or adjustment work, making it possible to realize a small and highly reliable second harmonic generation device.

(b) Since the resonator length of the Fabry-Perot resonator can be made small, the inter-mode exposure (free spectral range) of the resonance peak of the Fabry-Perot resonator can be made large. In addition, since the resolution (resonance width) can be sufficiently large, 1
The wavelength of the next incident laser light (primary light) can be synchronized to the resonant conditions of the rush by adjusting the operating temperature.

Further, the advantages of the configurations described in each of the above claims (3) are the same as those of claim (11).

〔Example〕

Hereinafter, three types of embodiments of the monolithic type second harmonic generation device including the above-mentioned Fabry-Perot resonator will be described with reference to the drawings.

Example 1 shows a structure in which a second-order harmonic generating material layer is sandwiched between two dielectric multilayer laminated reflectors (wavelength selective reflectors) that constitute a Fabry-Perot resonator for first-order light. It is. In this embodiment I, an external laser diode is used as the excitation a (primary light source) and can generate second harmonic light in both transmission mode and reflection mode.

This first embodiment shows a general configuration that is also used in other embodiments.

Example 2 shows a configuration in which the configuration of Example 1 and a surface-emitting laser are monolithically combined to provide a semiconductor blue laser light source.

Example 3 shows a configuration in which the Fabry-Perot resonator structure is applied to an optical waveguide to increase the intensity of primary incident light.

Big side” 1 Embodiment 1 will be explained based on FIGS. 1 to 3.

This embodiment corresponds to claim 11, and as shown in FIG. 30, a second harmonic generation material layer 40 made of an optical nonlinear material, and a dielectric multilayer laminated reflector (λ/4 wavelength selective reflector) 50 are sequentially grown. Semiconductor multilayer laminated reflector 30 with layer 40 sandwiched therebetween.
and a dielectric multilayer laminated reflector 50, and one
A configuration in which the second-order light is incident on the second-order harmonic generating material layer 40,
The semiconductor multi-layer laminated reflector 30 and the dielectric multi-layer laminated reflector 50 are exposed to 1 which is incident on the second harmonic generation material layer 40 from the outside.
A Fabry-Perot resonator is constructed for the following light.

The semiconductor multilayer laminated reflector 30 of the ten substrates has a low refractive index layer 31 having a refractive index of nA at a wavelength λ in vacuum and a thickness of λ/4n laminated on the buffer layer 20, A high refractive index layer 32 with a refractive index of nG (nG>nA) at a wavelength λ in vacuum and a thickness of λ/4n6 is laminated, and a low refractive index layer 31 with a refractive index of nA and a thickness of λ/4nA is laminated. and high refractive index layers 32 with a refractive index of 06 and a thickness of λ/4n are laminated alternately, and finally a high refractive index layer 32 with a refractive index of n and a thickness of λ/4n6 is laminated. There is.

The second harmonic generation material layer 40 is made of a material having optically non-linear characteristics among the Rho group compound semiconductors or other compound semiconductors, such as K Ti OP.
03 etc. are used. The refractive index at the wavelength λ of this second harmonic generation material layer 40 is ns, and the thickness is the coherent length 2nλ/4ns (n is an integer). Depending on the refractive index of the mirror 50, the thickness may be (2n+1) λ/4n.

The dielectric multilayer laminated reflector 50 on the opposite side of the substrate 10 includes a high refractive index layer 51 with a refractive index of n at wavelength λ and a thickness of 2/4 nH, and a high refractive index layer 51 with a refractive index of nL at wavelength λ and a thickness of λ. /4
It has a structure in which low refractive index layers 52 of n, are alternately stacked, and the layer immediately above the second harmonic generating material layer 40 is of
When ns, it becomes a high refractive index layer with a refractive index of n and a thickness of λ/4n, and when nH<n, it becomes a low refractive index layer with a refractive index of nl- and a thickness of λ/4nt. This becomes the index layer 52.

A specific example of the crystal layer structure in the above second harmonic generation device will be explained. Although the invention is not limited to this example, it is presented as an example of an application that can be realized with current crystal growth techniques. For example, GaAs is used as the substrate 10;
This is because the V group high crystalline pickling technology is well established. The buffer layer 20 has the same G as the substrate 10.
AAs is laminated. In addition, the semiconductor multilayer laminated reflective mirror 3
0, an AlAs layer is used as the low refractive index layer 31, and an AlAs layer is used as the high refractive index layer 32, for example.
-X As layer (specific examples include Al1o, :+G
a O', 7 A 5 layers) is used. Depending on the purpose, this layer may be ZnS, Zn5e, ZnSSe which is a mixed crystal thereof, or ZnS/ZnS
It may also be composed of an e superlattice or the like.

Many dielectric materials can be used in the dielectric multilayer laminated reflecting mirror 50, provided that they are transparent to second harmonic light. For example, a combination of a SiO□ layer and a ZrO2 layer is one example.

In the second harmonic generation device having the above structure, the semiconductor multilayer laminated reflector 30 and the dielectric multilayer laminated reflector 50
constitutes a Fabry-Perot resonator for the primary incident light. When the output wavelength of the laser that makes the first-order light incident on the second-order harmonic generation device is synchronized with the Fabry-Bérot resonance condition, the intensity of the first-order incident light will change to the second-order harmonic generation material layer 40, which is a nonlinear material. is strengthened where it exists, and as a result, the second harmonic generation efficiency increases. In other words, high intensity second harmonic light is generated from the second harmonic generation material layer 40,
For example, the light is radiated to the outside through the dielectric multilayer laminated reflector 50.

FIG. 1(b) shows the intensity distribution of the first-order light in the second-order harmonic generation device of FIG. It can be seen that the intensity of the primary light is low in the multilayer laminated reflecting mirror 30 and the dielectric multilayer laminated reflecting mirror 50.

The second harmonic generation device of this embodiment can be either a reflection type or a transmission type second harmonic generation device depending on the transmittance of light at a certain desired wavelength to the substrate in relation to the laser which is the primary light source. It is also possible to implement it as a device.

FIG. 2 shows an embodiment of a reflective second harmonic generation device. In FIG. 2, 61 is a laser light source that is composed of a laser diode and generates primary light, 62 is a lens, and 6
3 is a lens, 64 is the second harmonic generation device shown in No. 11, 65 is a dichroic mirror (dielectric coated mirror) that reflects the first order light and transmits the second harmonic light, and 66 is a lens. It is.

In the above configuration, the primary light emitted from the laser light source 61 is made into parallel light by the lens 62, irradiated onto the dichroic ink mirror 65, reflected by the dichroic mirror 65, and focused by the lens 63 to produce a second harmonic. Generation device 6
4. As a result, the second harmonic generation device 64
Inside, a standing wave of primary light is generated, and part of the secondary harmonic light generated by this propagates toward the substrate, while the rest is reflected and radiated to the outside. The second harmonic light emitted to the outside from the second harmonic generation device 64 is made into parallel light by the lens 63 and then transmitted to the dichroic mirror 65! ! q shot,
The light passes through the dichroic mirror 65 and is focused by the lens 66. On the other hand, the first-order light leaking from the second-order harmonic generation device 64 is reflected by the dichroic mirror 65 and radiated in a direction different from that of the second-order harmonic light, so that the first-order light and the second-order harmonic light are separated.

FIG. 3 shows an embodiment of a transmission type second harmonic generation device. In FIG. 3, 71 is a laser light source that is composed of a laser diode and generates primary light, and 72 is a lens. 73 is a second harmonic generation device similar to that shown in FIG. 1, and is composed of a substrate 74a and an epitaxial layer 74b laminated thereon. It constitutes a generating material layer and a dielectric multilayer laminated reflecting mirror. In this example, the portion of the substrate 74a that transmits the primary light is removed from the rear side by etching to reduce the absorption of the primary light by the substrate 74a, but this is not necessary if the absorption of the primary light can be ignored. There isn't.

75 and 76 are dichroic mirrors that reflect primary light and transmit secondary harmonic light, and 77 is a lens.

In the above configuration, the first-order light emitted from the laser light #71 is focused by the lens 72 and enters the second-order harmonic generation device 73. As a result, within the second harmonic generation device 73, a standing wave of the first order light is generated as in the case of FIG. radiated to. In this example, 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 passes through the dichroic mirror 75, is made into parallel light by the lens 77, and is emitted through the dichroic mirror 76.

On the other hand, the primary light leaking from the second harmonic generation device 73 is reflected by the dichroic mirror 75 and returns to the second harmonic generation device 73.
The leaked primary light is reflected by the dichroic mirror 76 and radiated in a direction different from that of the secondary harmonic light, thereby achieving complete separation of the primary light and the secondary harmonic light.

In addition, in the above, two dichroic mirrors 75.7
6 is used, but this is to improve the separation between the first order light and the second harmonic light, and the dichroic mirror 75 is used.
．． Only one of 76 may be provided.

The reflection-type and transmission-type second-order harmonic generation devices described above have the following advantages over normal waveguide-type second-order harmonic generation devices.

■ There is no need to align the primary light to an optical waveguide with minute dimensions.

(2) The second harmonic generating substance N40 only needs to exist in a minute space, so the cost is low.

■ Since long-term stable integration with vertical lasers is possible, costs are lower and the number and size of parts can be reduced.

In particular, in the reflective mode shown in Figure 2, if the material layer has an appropriate layer structure, it can be used without any further processing.
It can be used as a second harmonic generation device.

Tominen I Embodiment 2 will be explained based on FIGS. 4 to 7.

This embodiment corresponds to claim (2), and as shown in FIG. A second harmonic generation material layer 83 is laminated on the substrate 88 and the first order light from the semiconductor laser is incident thereon;
It is provided with a dielectric multilayer laminated reflecting mirror 82 and a semiconductor multilayer laminated reflecting mirror 85 that constitute a Fabry-Perot resonator for secondary light, and the above structure is formed on a substrate 81 made of, for example, GaAs.

The dielectric multilayer laminated reflection mirror 82 has a structure in which 5ift layers and 2 ZrQ layers are alternately laminated, and is transparent to second harmonic light, and its thickness etc. are the dielectric multilayer lamination reflection mirror shown in FIG. It is similar to the mirror 50.

The second harmonic generating material layer 83 is made of an It-Vl group compound semiconductor similar to that shown in FIG. 1, and has a thickness of, for example, about 0.5 to 1.0 μm.

The semiconductor multilayer laminated reflecting mirror 85 includes p-Aeo, IoGao
, qoAS layer and p Aj! o, 7oGao, 3oAs
It has a semiconductor laminated structure in which layers are alternately laminated, and its thickness etc. are the same as the semiconductor multilayer laminated reflector 30 shown in FIG.

The compound semiconductor multilayer structure 88 is composed of a multilayer structure of AIC and aAS or a multilayer structure of GaAs and AIGaAS.
j! o, ioG a O,? OA S Etchist 7
1 layer 88a, n ARo, 5b Gao, aaAS cladding N88b, n-GaAs active layer 88c, pA
1- o, 33 C+ ao, 6? A3 cladding layer 88d constitutes a surface emitting laser (SEL).

84 is a cap layer provided on the surface of the semiconductor multilayer reflective layer 85, and is made of, for example, p''-GaAs.

87 is a buried layer made of, for example, n-GaAs. 8
9 is a buffer layer made of n-GaAs. 86a and 86b are metal electrodes, respectively.

In this embodiment, the second harmonic generation material layer 83 and the compound semiconductor multilayer stacked structure 88 constituting the surface emitting laser (SEL) are integrated, so the number of parts is reduced and the structure is small and reliable. A high second harmonic light source can be provided. Furthermore, in this embodiment, since the dielectric multilayer laminated reflector 82 and the semiconductor multilayer laminated reflector 85 that constitute the filter and the reflector are integrated, the second harmonic generation efficiency can be doubled, and the dielectric Body multilayer laminated reflector 82
The intensity of the second harmonic light emitted through can be increased.

The most direct way to integrate a Fabry-Bello resonator and a surface-emitting laser in order to increase the efficiency of second-order harmonic generation is to integrate the compound semiconductor that makes up the semiconductor laser, as shown in Figure 4. The second harmonic generating material layer 83 made of a compound semiconductor is directly embedded in the multilayer laminated structure 88. This approach has already been proposed in other patents. By using the same resonator cavity, it is confirmed that the intensity of the first order light is maximum at the second harmonic generating material layer 83. This approach becomes even more effective by using the dielectric multilayer laminated reflector 82 and the semiconductor multilayer laminated reflector 85, which have a higher reflectance than reflectors used in ordinary lasers. The reason for this is that what is important in this case is to increase the intensity of the primary light within the cavity, not to increase the output power of the primary light. Since the dielectric multilayer laminated reflector 82 transmits the second harmonic light and reflects the first order light, in order to increase the second harmonic generation efficiency with this method, it is necessary to make sure that the second harmonic light and the first order light are It has the advantage of being distributed.

The above approach is limited by the intensity of the primary light in the laser cavity. It is therefore advantageous to increase the intensity of the primary light beyond that desired for the laser 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-Bello 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;
2 is a dielectric multilayer laminated reflector (dyke mirror) consisting of a structure in which 5+02 layers and ZrO layers are alternately laminated.
, 93 is a second harmonic generation material layer (high light intensity second harmonic generation region) made of a ■-■ group compound semiconductor, and 94 is n
A12.

Ga6. q6As layer and nA! l. , t. Ga
o, 36A This is a semiconductor multilayer laminated reflective mirror (dichroic mirror) consisting of a structure in which five layers are alternately laminated.

95 is a compound semiconductor multilayer structure (laser active region) constituting a surface emitting laser, for example nAj! o,
3oGao, taAs etch stop layer 95a, and n
A 7+6. sbG ao, 44AS craft layer 9
5b, n-GaAs active layer 95C, p Alo,
xsGaa, and a 67AS cladding layer 95d. 9
6 is a semiconductor multilayer laminated reflecting mirror (dichroic mirror) having a structure in which three layers of pA 1 o, +oGa e, qoA and layers of p AN-o, qoGao, 3oAs are alternately laminated. 97 is a buried layer made of n-GaAs, 99 is a cap layer made of p'-GaAs,
100 is a buffer layer made of n-GaAs.

98a and 98b are metal electrodes, respectively.

The difference from the structure in FIG. 4 is that the second harmonic generation material layer 93
The other structure is the same as that shown in FIG. 4 except that a semiconductor multilayer laminated reflector 94 is provided between the compound semiconductor multilayer laminated structure 95 and the compound semiconductor multilayer laminated structure 95.

In the second harmonic generation device having the above structure, the n-type semiconductor multilayer laminated reflector 94 and the p-type semiconductor multilayer laminated reflector 96 are connected to the compound semiconductor multilayer laminated structure 95 that constitutes the GaAs-based laser diode. Working as a laser cavity, the primary light resonates between the semiconductor multilayer laminated reflecting mirrors 94 and 96 as shown by arrow A in FIG. 5, and a laser beam serving as the primary light is obtained from this laser structure. This first-order light enters a second-order harmonic generation material layer 93 made of a II-Vl group compound semiconductor, where n
The primary light resonates again as shown by arrow B due to the cavity formed by the semiconductor multilayer laminated reflecting mirror 94 and the dielectric multilayer laminated reflecting mirror 92, and the intensity of the primary light increases in the second harmonic generation material layer 93. 2 generated in the second harmonic generation material layer 93
The third harmonic light passes through the dielectric multilayer laminated reflector 92 as indicated by the arrow C.
It will be radiated to the outside like this.

Furthermore, the
By using a dielectric multilayer laminated reflector that reflects and returns the second harmonic light, it is possible to double the output power of the second harmonic light.

Such a dielectric multilayer laminated reflector that prevents and returns secondary harmonic light from entering the laser active region has a structure that is transparent to the primary light and reflects the second harmonic light, and is transparent to the primary harmonic light and reflects the second harmonic light. The returned second harmonic light must be placed in a position where it is in phase with the original output light. FIG. 7 shows a second modification of the second harmonic generation device in which such a dielectric multilayer laminated reflector is added. In the 7th session, 10
1 is a dielectric multilayer laminated reflector that reflects primary light and is transparent to secondary harmonic light; 102 is a secondary harmonic generating material layer; 10
3 is a dielectric multilayer laminated reflector that reflects primary light; 104 is a dielectric multilayer laminated reflector that reflects secondary harmonic light and is transparent to primary light; 105 is a laser diode active region; 106 is a dielectric multilayer laminated reflector that reflects primary light; Laminated structure of electrodes, insulators, dielectrics, etc., 107
is the substrate.

As described above, when the structure includes the dielectric multilayer laminated reflector 104, the second harmonic light is emitted from the second harmonic generation material layer 102 in the direction of the dielectric multilayer laminated reflector 101 as shown by the arrow. is radiated to the outside through the dielectric multilayer laminated reflector 101. In addition, the second harmonic generation material layer 102
The second harmonic light emitted from the dielectric multilayer laminated reflector 103 in the direction of the dielectric multilayer laminated reflector 103 as shown by the arrow E is emitted from the dielectric multilayer laminated reflector 1.
04, the direction is reversed as shown by arrow F, and the second harmonic light of F is radiated to the outside through the dielectric multilayer laminated reflector 101. As shown by arrow F, the second harmonic light of F is in phase.

Inu potato ray Example 3 will be explained based on FIG. 8.

This embodiment corresponds to claim (3). In Examples 1 and 2, the heel was perpendicular to the substrate, but this Example 3 involves a dielectric coating that increases the intensity of primary light in an optical waveguide parallel to the substrate.

FIG. 8 ta+ shows a side sectional view of the second harmonic generation device of Example 3, FIG. .

In FIG. 8, 110 is a substrate made of a second harmonic generating material such as LiNbC)+, 112b is a protrusion provided by etching one surface of the substrate 110, and 112a is a protrusion 112.
This is a high refractive index material embedded in the grooves provided on the surface of b. The high refractive index material 112a is made of a material that has a higher refractive index for light waves of the same wavelength than the second harmonic generating material. And a convex strip 112 made of a second harmonic generating substance.
The optical waveguide 112 has a structure in which a high refractive index material 112a, which has a higher refractive index for light waves of the same wavelength than a second harmonic generating material, is embedded in a groove formed on one surface of the optical waveguide 112.

Further, on both end faces of the optical waveguide 112, dielectric multilayer reflective mirrors 111 and 113 forming a Fabry-Perot resonator having a structure similar to that described in the previous embodiment are laminated.

In the above structure, as shown by the arrow G, the primary light passes through the dielectric multilayer laminated reflector 111 and passes through the leading waveguide 112.
When the first-order light enters the high refractive index material 112a of
1 and 113, the intensity of the primary light within the optical waveguide 112 is increased, and the intensity of the second harmonic light generated within the convex portion 112b of the optical waveguide 112 is increased, and the dielectric multilayer laminated reflector High-intensity second-order harmonic light is emitted as shown by arrow H through 113.

The purpose of this embodiment is to increase the efficiency of second harmonic generation techniques using waveguides in some way. In particular, use of this embodiment is extremely useful in a system in which phase matching is achieved in an optical waveguide using different modes for primary light and secondary harmonic light. Phase matching between different waveguide modes is extremely sensitive to the thickness and other parameters of the optical waveguide, and it is difficult to phase match over a certain length of the optical waveguide to obtain a corresponding second harmonic output power. Very difficult. Therefore, as in this embodiment, with a short optical waveguide 112 of about 5 to 10 μm,
Moreover, if a corresponding output power of second-order harmonic light can be obtained without being so restricted by phase matching, there will be an extremely large advantage.

As described above, both ends of the guide waveguide 112 are camped with the dielectric multilayer laminated reflectors 111 and 113, and the optical waveguide 1
If the intensity of the first-order light in 12 is increased, the output power of the second-order harmonic light will also increase. Such dielectric multilayer laminated reflecting mirrors 1]1, 1.13 have already been put into practical use in recent laser guides. The end face of the waveguide 112 is formed by cleavage etching or a combination of the two, as in the case of laser.

〔Effect of the invention〕

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

(1) One part can have multiple functions,
It can be made smaller and more reliable, and it can be manufactured at a lower cost.

(2) By using a macroscopically sized substrate as the growth substrate, a relatively thin second harmonic generating material layer can be deposited in a well-controlled manner, resulting in a coherent length layer thickness. Obtained with good reproducibility.

(3) Since the interval between the resonances of the Fabry-Perot resonator, that is, the wavelength spectral region between one resonance and the next resonance, and the resonance width can be made sufficiently large, the wavelength of the primary incident laser light can be adjusted by adjusting the operating temperature. By doing this, synchronization to resonance conditions can be easily achieved.

[Brief explanation of drawings]

11EI (a) is a cross-sectional view showing the structure of Example 1 of the second harmonic generation device of the present invention, and FIG. 1(b) is the light intensity distribution in the second harmonic generation device of FIG. FIG. 2 is a schematic diagram showing the structure of a reflection type second harmonic generation device using the device of Example],
FIG. 3 is a schematic diagram showing the structure of a second-order harmonic generation device of the i3 type, FIG. 4 is a cross-sectional view showing the structure of Example 2 of the second-order harmonic generation device of the present invention, and FIG. is a schematic diagram showing a first modification of the second embodiment, FIG. 6 is a cross-sectional view, FIG. 7 is a cross-sectional view showing a second modification of the second embodiment, and FIG.
Figure fa1. (bl, (C1 are 2 of this invention, respectively)
FIG. 7 is a side cross-sectional view, a plan view, and a front cross-sectional view showing the structure of Example 3 of the harmonic generation device. 30... Semiconductor multilayer laminated reflecting mirror, 40... Second harmonic generating material layer, 50... Dielectric multilayer laminated reflecting mirror, 82
... Dielectric multilayer laminated reflecting mirror, 83... Second harmonic generating material layer, 85... Semiconductor multilayer laminated reflecting mirror, 88...
- Compound semiconductor multilayer stacked structure, 92... Dielectric multilayer stacked reflector, 93... Second harmonic generation material layer, 94...
・Semiconductor multilayer laminated reflector, 95...Compound semiconductor multilayer laminated structure, 96...Semiconductor multilayer laminated reflector, 101・
... Dielectric multilayer laminated reflecting mirror, 102... Second harmonic generating material layer, 103... Dielectric multilayer laminated reflecting mirror, 104
... Dielectric multilayer laminated reflecting mirror, 105... Compound semiconductor multilayer laminated structure, l 1. l... Dielectric multilayer laminated reflector, 112... Optical waveguide, 113... Dielectric multilayer laminated reflector t. Figure 93...Second harmonic generation snout page layer rod diagram■■...Dielectric multilayer cinder reflector■...Compound semiconductor multilayer stacked structure

Claims (3)

[Claims] (1) A second harmonic generation material layer is laminated with the second harmonic generation material layer sandwiched therebetween, and is fabricated for primary light.
A second harmonic generation device comprising a plurality of multilayer laminated reflecting mirrors forming a Perot resonator. (2) a compound semiconductor multilayer stacked structure constituting a semiconductor laser that generates primary light; and a second harmonic generation material layer stacked on the compound semiconductor multilayer stacked structure and into which the primary light from the semiconductor laser is incident. , a plurality of multilayer laminated reflecting mirrors that are laminated with at least the second harmonic generation material layer sandwiched therebetween and constitute a Fabry-Perot resonator for the first order light. (3) A light guide having a structure in which a high refractive index material having a higher refractive index for light waves of the same wavelength than the second harmonic generating material is embedded in a groove formed on one surface of the convex strip made of a second harmonic generating material. a waveguide, and the 1st layer is laminated on both end faces of the optical waveguide.
A second harmonic generation device comprising a plurality of multilayer laminated reflectors forming a Fabry-Perot resonator for secondary light.