JP2006332565A - Laser equipment using sub-wavelength periodic lattice - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the simple laser equipment that employs a sub-wavelength periodic lattice as a resonator to generate a laser beam and continuously varies the wavelength of the generated laser beam in a wide range of wavelength based on a simple principle called "mechanical pitch control". <P>SOLUTION: This equipment has a resonator of sub-wavelength periodic lattices composed of gain materials and arranged at regular pitches, and an excitation light source for emitting an exciting light to the above resonator. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser device using a subwavelength periodic grating.

A sub-wavelength periodic grating is a periodic structure that has a period shorter than the wavelength and does not generate higher-order diffracted waves. Various elements such as a resonance grating, a deflection element, a phase plate, and an antireflection structure using the same have been proposed.
As an example, FIG. 1 shows the structure of a resonant grating (see Non-Patent Document 1). As shown in FIG. 1A, the resonant grating 100 is composed of two substances (substances having a refractive index of 2.1) 114 and (substances having a refractive index of 2.0) 112 having different refractive indexes, a width of 314 nm, and a thickness. The structure is such that the thickness is 134 nm and is mounted on the material 130 having a refractive index of 1.52. When light is input to this grating and the reflected wave is measured (see FIG. 1 (b)), it can be seen that the reflectance is approximately 1 at a wavelength of 550 nm, and the light is almost totally reflected there. This is because light propagates inside the grating and undergoes multiple reflections to cause resonance. The resonance wavelength and resonance band are determined by the period, refractive index, thickness, surrounding refractive index, and the like, which are parameters relating to the grating.
A laser device that uses the resonance of the sub-wavelength periodic grating as a laser resonator has not been proposed yet.

S. Tibuleac and R. Magnusson, “Reflection and transmission guided-mode resonancefilters,” J. Opt. Soc. Am. A, Vol. 14, No. 7, (1997), pp. 1617-1626. D. Sameoto, T. Hubbard, and M. Kujath, “Operation of electrothermal and electrostatic MUMPs microactuators underwater,” J. Micromech. Microeng. Vol. 14 (2004), pp.1359-1366. Young-Hyun Jin, Kyoung-Sun Seo, Young-Ho Cho, Sang-Shin Lee, Ki-Chang Song and Jong-Uk Bu, “An optical microswitch chip integrated with silicon waveguides and touch-down electrostatic micromirrors,” J. Micromech Microeng., Vol.14 (2004) pp.1674-1681. "Next-generation precision positioning technology", Fuji Techno System Publishing, first edition issued on April 25, 2000

  An object of the present invention is to provide a simple laser device using the resonance of a sub-wavelength periodic grating as a laser resonator. It is also an object of the present invention to produce a laser device using a subwavelength periodic grating using a semiconductor microfabrication technique. Another object of the present invention is to make the generated laser light continuously variable over a wide range of wavelengths based on the simple principle of mechanical pitch control of the sub-wavelength periodic grating.

In order to achieve the above object, the present invention comprises a resonator composed of sub-wavelength periodic gratings of gain material arranged at a constant pitch, and a pumping light source that makes pumping light incident on the resonator. This is a laser device.
The resonator is preferably a two-layer grating having a grating layer and a waveguiding layer, and can be easily constructed.

The resonator has a periodic structure of a solid non-gain material having a spring shape in a liquid or gas gain material, and the periodic structure is connected to an actuator having a variable period, The resonance wavelength of the resonator can be changed by changing the period of the periodic structure with an actuator.
The resonator has a periodic structure of a solid gain material having a spring shape in a non-gain material of vacuum, liquid, or gas, and the periodic structure is connected to an actuator having a variable period, The resonance wavelength of the resonator can be changed by changing the period of the periodic structure with an actuator.

  With the above configuration, a simple laser device can be provided by utilizing the resonance of the sub-wavelength periodic grating as a laser resonator. A laser device using a sub-wavelength periodic grating can also be produced using a semiconductor microfabrication technique. Further, based on the simple principle of mechanical pitch control of the sub-wavelength periodic grating by an actuator, the generated laser light can be continuously tunable over a wide range of wavelengths.

Embodiments of the present invention will be described with reference to the drawings.
First, an embodiment of a sub-wavelength periodic grating (resonant grating) used in the laser apparatus is shown in FIG. FIG. 2A shows a single-layer lattice composed of two materials 112 and 114 having different refractive indexes as shown in FIG. FIG. 2B shows an embodiment of a resonant grating, which is an example of a two-layer grating. This two-layer grating has two separate configurations of a grating layer and a waveguide layer. The single-layer grating of FIG. 2A forms a periodic structure with a plurality of materials 112 and 114, and the grating layer also serves as a waveguiding layer. In the embodiment of the present invention described below, a laser is configured using a two-layer grating, but a single-layer grating can also be configured.

  The two-layer lattice will be described in detail with reference to FIG. The lattice layer and waveguide layer of the two-layer lattice shown in FIG. 3A need to have a higher refractive index than the surroundings, as shown in FIG. A diffraction wave is generated inside the waveguide layer having a high refractive index. In FIG. 3A, when an incident wave i is incident, resonance occurs when the phases of the transmitted waves t and s cancel each other. The analysis of the two-layer lattice shown in FIG. 3 will be described below. Among them, the basic principle model of the resonant grating will be described in detail below.

<Basic principle model>
Here, it is assumed that the grating layer is very thin, and it is assumed that the incident wave i is incident on the grating at an angle θ as shown in FIG. Further, it is assumed that the electric field vector of the incident light is parallel to the grating grooves (TE polarized light). In the resonance phenomenon, the two waves of the transmitted wave t and the diffracted wave s in the figure cause an interference in a state where the phase is 180 degrees out of phase, and the energy of the waves passing through to the lower layer due to this interference cancels each other and becomes zero. is required. Since the energy that cancels out and goes to the lower layer is zero, light does not pass through to the lower layer. That is, all incident light is reflected.

First, the relationship of the diffracted wave with respect to the incident wave i is expressed by the following equation.
Here, k is a wave vector, k = 2π / λ, K = 2π / Λ, and m is an arbitrary integer. This equation (1) is a general diffracted wave equation. Here, if the phase difference between the transmitted wave t and the diffracted wave s is Φ, Φ can be expressed by the equation Φ = Φ _p + Φ _r + 2Φ _d . Where Φ _p is the phase shift due to the optical path difference. [Phi _r is the phase shift due to total reflection at the waveguide layer lower surface. [Phi _d represents the deviation of the phase to undergo the influence of diffraction by grating.
The phase difference due to the first optical path difference is expressed by the following equation.
Here, _{k 3} is represented by _k 3 ₌ n 3 _ksin the propagation constant in the waveguide layer (φ), v is the thickness of the waveguide layer, p is an arbitrary integer.

Next, the phase change due to total reflection at the waveguiding layer is obtained from the Fresnel equation for TE polarized light.
It is represented by Here, Φ ₄ is expressed by the Fresnel phase change caused by the difference in refractive index between the waveguide layer and the substrate surface.
Finally, the phase change due to diffraction. Here, first, a phase change of π / 2 occurs by diffraction. Furthermore, considering the Fresnel phase change (assumed to be Φ ₁ ) resulting from the refractive index difference between the grating and the surrounding medium
It is represented by From the above, the total phase change of the waves of t and s
It is represented by When this phase change is exactly π, t and s cause interference that cancels each other, which is a basic condition for resonant reflection.

  The two-layer resonant grating described above is used as a laser resonator. For this purpose, for example, as shown in FIG. 4, a resonance grating having a grating layer 222 and a waveguide layer 224 made of a methyl methacrylate resin (Polymethylmethacrylate: PMMA, refractive index 1.49) in which a laser dye (Rhodamine 6G) is dissolved. 200 is created. When excitation light enters such a resonant grating 200, when the incident light is multiple-reflected by the waveguide layer 224, the light is amplified and laser light oscillates.

<Resonator structure>
FIG. 5 shows a resonator 200 actually created. The grating shown in FIG. 5 does not process a laser dye into a grating, but processes a grating shape on a low refractive index SiO ₂ substrate (refractive index 1.45) 230, and then converts PMMA 220 into which the laser dye is dissolved. The lattice layer 222 and the waveguide layer 224 can be formed simply by coating. This is because the structure is simple and the processing is completed in one etching process. Further, even if the dye is deteriorated, the resonator can be easily re-formed by re-applying the laser dye.

  FIG. 6 shows the result of measuring the reflectivity of the resonant grating (see FIG. 6A) created as shown in FIG. As shown in FIG. 6B, almost total reflection is performed at a single wavelength of 591.3 nm. As shown in FIG. 6C, the grating period and the peak wavelength have a proportional relationship. As is clear from this, the peak wavelength changes as the period changes. Therefore, considering the fluorescence band (560 to 650 nm) of the dye (Rhodamine 6G) used here, the grating period was determined so that the peak wavelength was in this band. Specifically, those having a grating period of 360, 380, 390, 400, 410, 420, 440, and 460 nm were prepared.

<Production process>
FIG. 7 shows an outline of the manufacturing process.
In FIG. 7A, an electron beam resist (EB resist) 240 is applied on the quartz glass 230 to create a lattice, and electron drawing (EB drawing) is performed. In order to improve the adhesion between the glass 230 and the resist 240, Hexamethyldisilazane (HMDS) was applied before applying the resist. In addition, since the glass 230 is a non-conductor, a phenomenon such as charge-up occurs, and basically, even if EB drawing is performed, clean patterning cannot be performed. Therefore, this time, a conductive polymer was applied on the resist. This makes it possible to perform EB drawing even on non-conductive materials.

Next, FAB (Fast Atom Beam) etching is performed to create a lattice in the quartz glass 230 (see FIG. 7B).
Then, the Rhodamine 6G-PMMA solution 220 is dropped on the substrate on the quartz glass on which the lattice is formed, and is spread uniformly by spin coating. The thickness was about 700 nm at about 2000 rpm for 20 s. After spin coating, the organic solvent is volatilized and solidified by baking at 50 ° C. for 1 hour and then at 80 ° C. for 3 hours. First, baking is performed for 1 hour in order to prevent bubbles from being generated inside due to a sudden temperature rise (see FIG. 7C).
In the above description, the solution that is the gain material is applied by spin coating, but the gain material can also be formed by an epitaxial growth method, a sputtering method, a vapor deposition method, a deposition method, or the like.

<Laser dye used in the embodiment>
As described above, in this embodiment, Rhodamine 6G • Perchlorate, which is a xanthine dye, is used as the laser dye. Rhodamine 6G has an absorption wavelength range of about 450 nm to 550 nm, and a fluorescence band of 550 nm to 650 nm.
PMMA was used as a polymer for solidifying the laser dye. PMMA is a very transparent substance with a transmittance of 90% in the visible region, and is a material widely used as a plastic optical component because of its low birefringence. The fluorescence intensity of xanthine dyes varies depending on the surrounding environment. As a general property, it dissolves at a molecular level in a polar solution and has a high quantum efficiency, but in a nonpolar solution, it precipitates without being dissolved and enters a quenching state. Therefore, in order to dissolve Rhodamine 6G in the PMMA solution, a solvent having polarity and soluble in PMMA is required.

The composition of the Rhodamine 6G-PMMA solution used in the embodiment is as shown in Table 1. First, Rhodamine 6G is dissolved in ethanol and stirred well. Stirring was carried out for about a day on a hot stirrer (about 45 ° C.). Then, methyl isobutyl ketone is added and stirred again under the same conditions. In a separate container, PMMA is well dissolved in chlorobenzene (the stirring conditions are the same as above). Finally, these two types of solutions are mixed and thoroughly stirred again (under the same conditions) to complete the Rhodamine 6G-PMMA solution. In order to obtain sufficient fluorescence from the dye, the order of the chemicals to be mixed is very important.

<Laser oscillation>
The laser oscillation using the two-layer grating created as described above will be described below. As shown in FIG. 8, excitation light was incident on the sub-wavelength periodic grating 200, and the emitted laser light was observed with a CCD camera 320 and a spectroscope 310 via a lens 340.
Actually, emission was observed when second harmonic (532 nm) pulsed light (pulse width: about 10 nm) (intensity: 19.1 mJ / cm ² ) of an Nd: YAG laser was applied as excitation light. The incident angle of the excitation light is about 45 degrees. As a result, as shown in FIG. 9A, the oscillation spectrum of single-mode laser light was observed from a resonator having a grating period of 390, 400, 410, and 420 nm. The oscillation wavelength corresponds to the grating period, and peaks were observed at 577.5, 591.3, 605.2, and 619.2 nm, respectively. In addition, three peaks are observed from the lattice having a period of 440 nm, and it can be seen that multimode oscillation occurs. The relationship between the period and the peak wavelength at this time is shown in FIG. It can be seen that there is a proportional relationship between each grating period and the oscillation wavelength. In this calculation, the refractive index of R6G-PMMA is 1.5. At this time, it can be confirmed that the peak wavelength of the calculated value and the measured value are in good agreement. The measured peak half width (Full Width Half Maximum: FWHM) is a similar value and is about ˜0.6 nm.

<Wavelength tunable laser>
As described above, laser oscillation can be performed using the sub-wavelength periodic grating (resonant grating), and thus the wavelength-tunable laser can be configured by changing the period of the sub-wavelength periodic grating.
A conceptual diagram of the configuration is shown in FIG. In FIG. 10A, for example, a resonant grating 410 made of a gain material that contains a laser dye autonomously with respect to the substrate 420 is provided, and the grating period of the resonant grating is changed using an actuator. A wavelength tunable laser is realized. The surrounding is made of non-gain material such as air.
FIG. 10B shows a configuration in which a resonant grating 410 made of a non-gain material is provided in the gain material 430. This configuration can also be a wavelength tunable laser. The gain material is gas or liquid, the non-gain material is solid, and the grating made of the non-gain material is moved by the actuator. The relationship between the gain material and the non-gain material, and the lattice structure (periodic structure) and the actuator will be described later.

<Configuration example of wavelength tunable laser>
FIG. 11 shows a configuration example of the wavelength tunable laser. In FIG. 11, the wavelength tunable laser 400 includes a sub-wavelength periodic grating 410 made of silicon, a comb electrostatic actuator 440 for making it movable, and an actuator between the actuator 440 and the resonant grating 410. The support spring 442 is configured. Both ends of the resonance grating are also supported by trifurcated springs (see FIG. 11B).
FIG. 12 shows how the wavelength tunable laser moves. As shown in FIG. 12A, by applying a voltage between the electrodes 451 and 452, the actuator is attracted by a voltage between plus and minus between the comb electrostatic actuators 440, and the sub-wavelength periodic grating The period of 410 changes (see FIG. 12B). The voltage-displacement characteristics are shown in FIG. Thus, when the grating period changes, the relationship between the grating period of the non-gain grating type structure using quartz as the grating material and the laser oscillation wavelength is shown in FIG. This figure shows that the oscillation wavelength increases continuously and linearly as the grating period increases.

<Lattice shape>
The shape of the lattice may be a structure in which each lattice is deformed at equal intervals. For example, a lattice having the shape shown in FIGS. 14A and 14B was formed. In the shape 1 shown in FIG. 14A, the beams of each lattice are connected to each other with springs of the same shape. The advantage of this structure is that the grating period can be changed uniformly. In order to avoid the concentration of pattern density in production, the shape 1 is a trifurcated spring (see FIG. 11B). By doing so, the period of the spring portion can be reduced to about 2/3 (400 nm) of the grating period.
In shape 2 shown in FIG. 14B, a spring is incorporated in the lattice to form a bellows shape. One common problem with MEMS devices is Stiction after the release of moving parts. This is, for example, a phenomenon in which an unexpected force is applied to the device during or after the process, and the movable part comes into contact with and adheres to the substrate or another structure. The cause of Stiction is said to be moisture contained in the air, and the surface tension sucks and fixes the structures together. Stiction is an unavoidable problem as long as there are devices in the air, but the symptoms can be reduced by devising the structural design. The elongated lattice beams in a self-supporting structure are vulnerable to lateral forces and are flexible. We thought to prevent the stiction of each beam of the lattice by inserting a support between the beams of the lattice of the shape 2 and making it bellows. By integrating the lattice with the spring, pattern density concentration can be avoided.

<Structure of tunable laser with tunable subwavelength periodic grating>
15 and 16 show structural examples of a wavelength tunable laser 400 using a variable subwavelength periodic grating. The configuration shown here is a schematic diagram showing the structure of a grating and an actuator made of gain material and non-gain material. When the gain material is solid, vacuum, liquid or gas is used as the non-gain material, and when the gain material is gas or liquid, solid is used as the non-gain material. The uppermost part of the wavelength tunable laser 400 using each type of variable sub-wavelength periodic grating shown in FIGS. 15 and 16 is covered with a cover 470.

  FIG. 15A shows a gain grating upper actuator type. In this configuration, a spring-like variable sub-wavelength periodic grating (periodic structure) 410 made of a solid gain material is connected to an actuator 440 formed in the same layer. By driving the actuator 440, the period of the spring-like periodic structure (lattice) 410 is variable. The periodic structure 410 is filled with a vacuum, gas or liquid made of the non-gain material 480. The other end supporting the actuator 440 and the periodic structure 410 is supported by a sacrificial layer material 460 formed on the substrate 420.

  FIG. 15B shows a non-gain grating upper actuator type. In this configuration, a spring-like variable sub-wavelength periodic grating (periodic structure) 410 made of a solid non-gain material is connected to an actuator 440 formed in the same layer. By driving the actuator 440, the period of the periodic structure (lattice) 410 is variable. The periodic structure 410 is filled with a gas or liquid 430 made of a gain material. The other end supporting the actuator 440 and the periodic structure 410 is supported by a sacrificial layer material 460 formed on the substrate 420.

  FIG. 16A shows a gain grating lower actuator type. In this configuration, a spring-like variable sub-wavelength periodic grating (periodic structure) 410 made of a solid gain material is connected to an actuator 440 formed on the substrate layer 420 via a sacrificial layer material 460. By driving the actuator 440, the period of the periodic structure (lattice) 410 is variable. The periodic structure 410 is filled with a vacuum, gas or liquid 480 made of a non-gain material. The other end supporting the periodic structure 410 is supported by a sacrificial layer material 460 formed on the substrate 420.

  FIG. 16B shows a non-gain grating lower actuator type. In this configuration, a spring-like variable sub-wavelength periodic grating (periodic structure) 410 made of a solid non-gain material is connected to an actuator 440 formed on the substrate layer 420 via a sacrificial layer material 460. . By driving the actuator 440, the period of the periodic structure (lattice) 410 is variable. The periodic structure 410 is filled with a gas or liquid 430 made of a gain material. The other end supporting the periodic structure 410 is supported by a sacrificial layer material 460 formed on the substrate 420.

<Fabrication of a tunable laser using a variable sub-wavelength periodic grating>
The manufacturing process is shown in FIGS. 17 and 18 (a) to (i). The grating shown in FIG. 17 is a non-gain grating (periodic structure) made of Si. As a rough flow, an electrostatic actuator is first formed and then a diffraction grating is formed. Finally, the sacrificial layer that supports them is removed and the movable part is released to complete.

(1) For production, a silicon on insulator (SOI) substrate was used as shown in FIG. The SOI substrate is a three-layer substrate in which an insulating layer made of SiO ₂ is provided on a support substrate layer made of Si, and an Si layer is further formed thereon. SOI is widely used in the manufacture of semiconductors, but in recent years it has also been used in the manufacture of devices for MEMS using SiO ₂ as a sacrificial layer. Since the upper layer forming the device is made of single-crystal Si, there is an advantage that the internal stress is small and the structure is not distorted even when the movable part is released.

(2) Next, as shown in FIG. 17B, a comb electrostatic actuator is patterned by an electron beam on the EB resist. Since it is a μm-scale actuator, patterning is possible even by photolithography, but since the width of the spring supporting the actuator was narrowed to about 1 μm, an electron beam (EB) exposure device with high drawing accuracy was used. did.

(3) In order to form an actuator, as shown in FIG. 17C, Si is etched vertically by ICP-RIE. The ICP-RIE used this time uses the Bosch process to realize high aspect ratio processing. By alternately flowing two gases of SF ₆ and C ₄ F ₈ , it is possible to perform deep etching while forming a protective film on the side wall of the structure. At this stage of the process, the actuator is not completely machined. Etching is stopped when the thickness of the device Si reaches 300 nm in order to form a diffraction grating. At this time, the etching rate is slower than the entire actuator portion having a high pattern density because etching gas is difficult to enter.

(4) Here, the device Si (300 nm thickness) left in the previous process is protected with a resist, and EB lithography is used (see FIG. 17D). Photolithography may be used.
(5) Etching is performed in the same manner as in the above process (3) to complete the actuator. (See FIG. 17 (e))
(6) As shown in FIG. 18F, the applied resist is removed.

(7) A resist is applied, and a diffraction grating is drawn by an electron beam (EB) (see FIG. 18G). Each actuator that has been processed in advance is drawn by performing pinpoint alignment one by one using EB. For this, the alignment function of EB was used. Alignment of X, Y, and θ axes is possible.
(8) As shown in FIG. 18 (h), a fast atom beam (FAB) processing apparatus was used to form a diffraction grating by etching. Unlike RIE, the particles are neutral and can be etched without being affected by charge-up during processing. Therefore, it is excellent in perpendicularity and suitable for etching a fine pattern. The disadvantage is that the etching rate is slow and the selectivity to the resist is poor because the physical processing elements by particle collision are larger than the reactive etching.

(9) Finally, sacrificial layer etching was performed (see FIG. 18 (i)). In wet etching, the formed diffraction grating is stictioned and broken due to the surface tension of the liquid during drying. Therefore, here, a method of etching with vapor phase HF vapor was adopted.
As described above, a basic configuration of a wavelength tunable laser having a non-gain grating can be manufactured.

<About the actuator>
In the above description, an example using an electrostatic actuator has been shown. However, the grating period can be changed using various actuators.
As an actuator that can be used in the present invention, a comb-type electrostatic actuator (see Non-Patent Document 2), a thermal expansion actuator (see Non-Patent Document 2), a hot cold arm thermal actuator (see Non-Patent Document 2), an electrostatic There are actuators (see Non-Patent Document 3), piezoelectric actuators (see Non-Patent Document 4), shape memory alloy actuators, and the like.
The material used for the actuator is the material used for the heater in the case of a thermal actuator, and for example, silicon, Ni or the like is used. For electrostatic actuators, use silicon or Ni. For piezoelectric actuators, use piezoelectric materials such as PZT.

<About gain material to be used>
In the above description, a plastic (PMMA) in which a laser dye is dissolved is used to constitute the gain material. However, examples of other gain materials include dyes used in dye lasers (see Table 2), active layer materials (GaN, GaAlAs, etc.) used in semiconductor lasers, phosphorescent emitters, fluorescent emitters (organic EL) One example is the organic EL material used in displays and the like.
The above-mentioned dye, phosphorescent luminescent material, and fluorescent luminescent material become a solid gain material by doping a plastic material such as PMMA, and become a liquid gain material by dissolving with a solvent. The active layer material used in semiconductor lasers is used as a solid.

<Non-gain material used>
As the non-gain material to be used, any material transparent to the laser oscillation wavelength may be used. For example, in the case of a tunable laser for visible light, non-gain materials include quartz, glass, plastic, ceramics, etc., if solid, water, methanol, ethanol, IPA, fluorinate, etc., if liquid, For example, air, vacuum, nitrogen, noble gas, etc. are practical candidate materials.
15 and 16, when the gain material is solid, the non-gain material is vacuum, liquid, or gas. When the gain material is gas or liquid, the non-gain material is solid. use.

It is a figure which shows the conventional subwavelength period grating (resonance grating). It is a figure which shows the structure of a single layer grating | lattice and a two-layer grating | lattice. It is a figure of the model which shows the function of a two-layer lattice. It is a figure which shows that a two-layer resonance grating can be used as a resonator of a laser. It is a figure which shows the structure of the produced 2 layer grating | lattice. It is a figure which shows the result of having measured the reflectance of the two-layer grating | lattice of FIG. It is a figure which shows the resonator preparation method of a two-layer grating. It is a figure which shows the structure which observes the laser beam of the produced 2 layer grating | lattice. It is a figure which shows the observed laser beam. It is a figure which shows the structure of the wavelength tunable laser using a variable subwavelength periodic grating. It is a figure which shows the basic composition of the wavelength tunable laser using the produced variable subwavelength periodic grating. It is a figure which shows that the period of the produced wavelength variable laser can be varied. It is a figure which shows a displacement, a voltage, and the wavelength of the laser beam to generate | occur | produce. It is a figure which shows the example of the shape of a grating | lattice. It is a figure which shows the structure of the gain material of a wavelength variable laser apparatus, a non-gain material, and an actuator. It is a figure which shows the gain material of a wavelength variable laser apparatus, a non-gain material, and another structure of an actuator. It is a figure which shows the preparation methods of the basic composition of a wavelength tunable laser apparatus. It is a figure which shows the continuation of the manufacturing method of the basic composition of a wavelength tunable laser apparatus.

Claims (4)

A resonator composed of sub-wavelength periodic gratings of gain material arranged at a constant pitch;
A laser apparatus comprising: an excitation light source that makes excitation light incident on the resonator. The laser device according to claim 1,
The laser device is a two-layer grating having a grating layer and a waveguide layer. The laser device according to claim 1,
The resonator has a periodic structure of a solid non-gain material having a spring shape in a liquid or gas gain material, and the periodic structure is connected to an actuator having a variable period,
A laser device, wherein the resonance wavelength of the resonator is changed by changing the period of the periodic structure by the actuator. The laser device according to claim 1,
The resonator has a periodic structure of a solid gain material having a spring shape in a non-gain material of vacuum, liquid or gas, and the periodic structure is connected to an actuator having a variable period,
A laser device, wherein the resonance wavelength of the resonator is changed by changing the period of the periodic structure by the actuator.