Method for improving organic semiconductor laser device, program, computer, and organic semiconductor laser device

Abstract

An organic semiconductor laser device having a supercell structure consisting of a first short pitch periodic structure having length WS1, a long pitch periodic structure having length WL, and a second short pitch periodic structure having length WS2 is improved by extending (WS1+WS2), shortening WL, extending (WS1+WL+WS2), or repeating the supercell structure.

Description

[Technical field]

[0001] The present invention relates to a method for improving an organic semiconductor laser device. [Background technology]

[0002] In conventional sensing technologies that project a light pattern, called "structured light", onto an object, such as two-dimensional and three-dimensional imaging (e.g., biometrics), laser sources with DOEs (diffractive optical elements) are known. DOEs are specially designed to split a single laser beam into multiple points, lines, or other shapes of light over a wide field of view. DOEs are large elements that consist of lenses and waveguides. Thus, the use of DOEs limits the miniaturization and integration density of such optical sensing systems, and increases the cost. Therefore, there is a need to develop a laser device that can emit split lasers without using DOEs.

[0003] On the other hand, it has become clear recently that organic semiconductors have great potential as gain media. Organic semiconductor lasers (OSLs) are attractive devices due to their low oscillation threshold, wide optical gain and fine wavelength tuning over a variety of molecular designs from blue to near infrared. 1-3 However, current injection lasers, i.e. OSLDs (Organic Semiconductor Laser Diodes), are still in their very early stages and require further development both in terms of materials and device structure. One of the major challenges for organic devices is the limited film thickness. For efficient carrier injection and transport in the organic layers, thin film structures of several hundred nm or so must be provided. Therefore, it is necessary to design the best optical cavity structure suitable for thin film OSLDs.

[0004] Optical cavities play a key role in improving the performance of organic lasers by trapping, amplifying and extracting light. 4 , DBR (Distributed Bragg Reflector) with VCSEL (Vertical Cavity Surface Emitting Laser) 5 , and DFB (distributed feedback) structure 6Among these cavities, the DFB cavity is a promising candidate for organic lasers. 7-9 In conventional inorganic semiconductor lasers, a first-order DFB cavity is used, allowing planar feedback and lasing. 10 In addition, second-order DFB resonators are also good candidates due to their surface emission. Furthermore, a mixed DFB resonator, which combines first-order and second-order resonators, has also been reported. The mixed DFB resonator combines the advantages of the first-order DFB resonator (strong lateral feedback) and the second-order DFB resonator (partial light extraction as surface emission), which allows the realization of surface-emitting lasers with low thresholds. 11 .

[0005] Although such a DFB structure has a low oscillation threshold, it has a major challenge in controlling the radiation angle distribution. For example, in face recognition and ToF (Time of Flight) technology, a large number of high-density laser beam spots are required because the sensor is capable of detecting the shape with high resolution and reconstructing the three-dimensional space (Non-Patent Document 1). 12 However, this angular gap limits applications because only a limited number of light rays are reflected by the object, reducing the resolution of the sensor. Similarly, this is important for various display applications. At the same time, the current density threshold must be significantly reduced by suitable DFB structure design, since organic gain materials are mostly optically and electrically weak under high power excitation. Especially for electrically driven OSLDs, the generation of triplets is large under current excitation based on sufficient spin statistics, i.e., singlets and triplets occur at a formation ratio of 1:3, so various annihilation processes such as STA (singlet-triplet annihilation) and TTA (triplet-triplet annihilation) are inevitable, and long-term triplets cause strong annihilation of radiative singlets (Non-Patent Document 2). 13 Therefore, in order to suppress these extinctions, it is highly desirable to reduce the threshold by optimizing the DFB structure. [Prior art documents] [Non-patent literature]

[0006] JPEG2025502517000002.jpg15170 Summary of the Invention [Problem to be solved by the invention]

[0007] Under these circumstances, the present inventors have conducted extensive research with the aim of providing an organic semiconductor laser device with a low oscillation threshold. Furthermore, the present inventors have conducted extensive research with the aim of providing an organic laser device capable of emitting split laser beams without using an additional optical system such as a DOE. [Means for solving the problem]

[0008] As a result of research by the present inventors to achieve the object, it was found that the oscillation threshold can be reduced by providing two or more supercell structures having first and second short pitch periodic structures and a long pitch periodic structure in an optical resonator structure and controlling the length of each periodic structure in a direction perpendicular to the grating grooves. Furthermore, the present inventors also found that a split laser beam with a narrow difference in diffraction angle can be obtained by controlling the length of each periodic structure in a direction perpendicular to the grating grooves. The present invention has been proposed based on such findings and can be realized by the following means.

[0009] [1] A method for improving an organic semiconductor laser device having an optical resonator structure and an optical amplification layer made of an organic semiconductor, comprising the steps of: the optical resonator structure includes at least one supercell structure having a first short pitch period structure, a long pitch period structure, and a second short pitch period structure; a first short pitch period structure disposed adjacent one end of the long pitch period structure and a second short pitch period structure disposed adjacent the other end of the long pitch period structure; At least two of (i) a direction perpendicular to the grating grooves of the first short pitch periodic structure, (ii) a direction perpendicular to the grating grooves of the long pitch periodic structure, and (iii) a direction perpendicular to the grating grooves of the second short pitch periodic structure are on a straight line. (1) Stretching (WS1+WS2); (2) Shortening the work week and (3) Stretching (WS1+WL+WS2); and (4) repeating the supercell structure; At least one of wherein WS1 is the length in a direction perpendicular to the grating grooves of the first short pitch periodic structure, WS2 is the length in a direction perpendicular to the grating grooves of the second short pitch periodic structure, and WL is the length in a direction perpendicular to the grating grooves of the long pitch periodic structure.

[0010] [2](1) is carried out by the method of [1].

[0011] [3] (2) is performed by the method of [1].

[0012] [4] (3) by the method of [1].

[0013] [5](4) is carried out by the method of [1].

[0014] [6] The method of [1] for carrying out (1) and (2).

[0015] [7] The method of [1] for carrying out (1) and (3).

[0016] [8] The method of [1] for carrying out (2) and (3).

[0017] [9] The method of [1] comprising carrying out (1), (2), and (3).

[0018] Any one of the methods [6] to [9], further comprising the steps of

[10] (4).

[0019]

[11] Any one of the methods according to [1] to

[10] , wherein (WS1+WS2) / WL is adjusted to 4 or more, for example, 10 or more, 50 or more, 90 or more, 150 or more, or 800 or more.

[0020]

[12] The method according to any one of [1] to

[11] , wherein (WS1+WS2) is adjusted to 1 μm or more, for example, 4 μm or more, 10 μm or more, 40 μm or more, or 200 μm or more.

[0021]

[13] The method according to any one of [1] to

[12] , wherein the WL is adjusted to 10 μm or less, for example, 2 μm or less or 0.6 μm or less.

[0022]

[14] The method according to any one of [1] to

[13] , wherein (WS1+WL+WS2) is adjusted to 2 μm or more, for example 5 μm or more, 20 μm or more, 50 μm or more, or 250 μm or more.

[0023]

[15] Any one of the methods [1] to

[14] , satisfying WS1=WS2.

[0024]

[16] Any one of the methods [1] to

[15] , wherein (i) a direction perpendicular to the grating grooves of the first short pitch periodic structure, (ii) a direction perpendicular to the grating grooves of the long pitch periodic structure, and (iii) a direction perpendicular to the grating grooves of the second short pitch periodic structure are all on a straight line.

[0025]

[17] The method of any one of [1] to

[16] , wherein a first short pitch periodic structure abuts one end of the long pitch periodic structure and a second short pitch periodic structure abuts the other end of the long pitch periodic structure.

[0026]

[18] The method of any one of [1] to

[17] , wherein the periodic structure is a lattice of ridges and grooves.

[0027]

[19] The method of any one of [1] to

[18] , wherein the first short pitch periodic structure and the second short pitch periodic structure are first-order gratings and the long pitch periodic structure is a second-order grating.

[0028]

[20] Any one of the methods [1] to

[19] , which is a method for reducing an oscillation threshold.

[0029]

[21] Any one of the methods [1] to

[19] , which is a method for narrowing the diffraction angle of laser light.

[0030]

[22] Any one of the methods [1] to

[19] , which is a method for reducing an oscillation threshold and narrowing a diffraction angle of laser light.

[0031]

[23] Any one of the methods [1] to

[22] , which is a method for designing an organic semiconductor laser device.

[0032]

[24] A method for evaluating an organic semiconductor laser device, comprising any one of the methods [1] to

[23] .

[0033]

[25] Any one of the methods [1] to

[24] , which is a method for manufacturing an organic semiconductor laser device.

[0034]

[26] A program for carrying out any one of the methods described in [1] to

[25] .

[0035]

[27] A computer that performs any one of the methods described in [1] to

[25] .

[0036]

[28] An organic semiconductor laser device manufactured by any one of the methods set forth in [1] to

[25] .

[0037]

[29] An optical resonator structure and an optical amplification layer made of an organic semiconductor; the optical resonator structure includes at least one supercell structure having a first short pitch period structure, a long pitch period structure, and a second short pitch period structure; a first short pitch period structure disposed adjacent one end of the long pitch period structure and a second short pitch period structure disposed adjacent the other end of the long pitch period structure; At least two of (i) a direction perpendicular to the grating grooves of the first short pitch periodic structure, (ii) a direction perpendicular to the grating grooves of the long pitch periodic structure, and (iii) a direction perpendicular to the grating grooves of the second short pitch periodic structure are on a straight line; An organic semiconductor laser device having at least one of a long (WS1+WS2), a short WL, a long (WS1+WL+WS2), and two or more supercell structures, where WS1 is the length in a direction perpendicular to the grating grooves of a first short pitch periodic structure, WS2 is the length in a direction perpendicular to the grating grooves of a second short pitch periodic structure, and WL is the length in a direction perpendicular to the grating grooves of a long pitch periodic structure.

[0038]

[30] An organic semiconductor laser device according to

[28] or

[29] , wherein the optical resonator structure has two or more supercell structures, and the two or more supercell structures are arranged so that a direction perpendicular to the lattice grooves is on a straight line.

[0039]

[31] The organic semiconductor laser device of

[30] , wherein WS1, WL, and WS2 of the two or more supercell structures are identical.

[0040]

[32] The organic semiconductor laser device of

[30] , wherein the lengths of the two or more supercell structures in a direction perpendicular to the lattice grooves are set randomly.

[0041]

[33] An organic semiconductor laser device according to any one of

[30] to

[32] , wherein the optical resonator structure has 10 or more supercell structures.

[0042]

[34] The organic semiconductor laser device according to any one of

[28] to

[33] , wherein the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure have grooves with a depth of 75 nm or less, for example, 20 to 70 nm.

[0043]

[35] The organic semiconductor laser device according to any one of

[28] to

[34] , wherein the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure have a DFB (distributed feedback) structure.

[0044]

[36] The organic semiconductor laser device of

[35] , wherein each DFB (distributed feedback) structure is selected from the group consisting of a first-order DFB structure, a second-order DFB structure, a third-order DFB structure, and DFB structures of higher orders.

[0045]

[37] The organic semiconductor laser device according to any one of

[28] to

[36] , wherein the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure are made of insulators.

[0046]

[38] An organic semiconductor laser device according to any one of

[28] to

[37] , wherein the first short pitch periodic structure, the long pitch periodic structure and the second short pitch periodic structure are periodically arranged and have ridges made of an insulator on an insulating substrate.

[0047]

[39] The organic semiconductor laser device of

[38] , wherein the ridge and the insulating substrate are made of different insulators.

[0048]

[40] The organic semiconductor laser device of

[38] , wherein the ridge is made of a silicon diode and the insulating substrate is made of a glass substrate.

[0049]

[41] The organic semiconductor laser device according to any one of

[38] to

[40] , wherein the surface of the insulating substrate is exposed at the bottom of the groove.

[0050]

[42] The organic semiconductor laser device according to any one of

[28] to

[41] , further comprising an organic layer on a surface of the optical resonator structure.

[0051]

[43] The organic semiconductor laser device of

[42] , further comprising a transparent protective layer on the organic layer opposite the optical resonator structure.

[0052]

[44] The organic semiconductor laser device of

[42] or

[43] , which emits a laser beam from the opposite side of the optical resonator structure to the organic layer.

[0053]

[45] The organic semiconductor laser device of

[43] , which emits a laser beam from the opposite side of the transparent protective layer to the organic layer.

[0054]

[46] An organic semiconductor laser device according to any one of

[28] to

[45] , which emits two or more types of diffracted light having different diffraction angles.

[0055]

[47] The organic semiconductor laser device of

[46] , wherein the difference in diffraction angle between the two or more types of diffracted light beams having the closest radiation direction is 8° or less, for example, 7° or less, or 6° or less.

[0056]

[48] ​​The organic semiconductor laser device according to any one of

[28] to

[47] , wherein the organic layer contains an organic compound having at least a stilbene unit.

[0057]

[49] The organic semiconductor laser device of any one of

[28] to

[48] , wherein the organic layer comprises 4,4'-bis[(N-carbazole)styryl]biphenyl (BSBCz).

[0058]

[50] The organic semiconductor laser device according to any one of

[28] to

[49] , wherein the organic layer has a thickness of 80 to 350 nm, for example, a thickness of 100 to 300 nm or 150 to 250 nm.

[0059]

[51] An apparatus selected from the group consisting of an in vivo sensing apparatus, a structured optical illumination apparatus, an optical detection apparatus, and a facial recognition apparatus, comprising one of the organic semiconductor laser devices of

[28] to

[50] . Effect of the Invention

[0060] Compatibility with all organic platforms and OLED technologies, monolithic integration of lasers of different colors, integration with electroluminescent devices and other organic devices enables miniaturization of structured light based sensors and optical sensor systems. [Brief description of the drawings]

[0061] [Figure 1] FIG. 2 is a schematic plan view showing an example of an optical resonator structure used in the present invention. [Diagram 2] FIG. 1 is a schematic plan view showing an optical resonator structure having three or more supercell structures with different lengths. [Diagram 3] 3 shows a simulation result regarding the angular dependence of laser light from a laser diode having the optical resonator structure shown in FIG. 2. [Figure 4] (a) SEM (scanning electron micrograph) of the mixed DFB sample with a secondary:primary lattice ratio of 4:12; (b) schematic top views of the mixed DFB samples with secondary:primary lattice ratios of 4:12, 4:36, and 4:200 (Λ corresponds to one supercell length and is the sum of one secondary lattice and two primary lattices); (c) cross-sectional view of the OSL device encapsulated with CYTOP and sapphire cover glass; (d) structural formula of 4,4'-bis[(N-carbazole)styryl]biphenyl (BSBCz) as gain medium and 4,4'-di(N-carbazolyl)biphenyl (CBP) as host. [Diagram 5] (a)-(c) Photonic band diagram (colored) and PL spectra (right) at θ=0°, as well as far-field emission patterns (bottom) for mixed DFB devices with (a) 4:12, (b) 4:36, and (c) 4:200 (secondary:first-order) ratios with a second-order DFB (4 periods). [Figure 6] (a) to (c) are PL (black) and lasing (red) spectra obtained at 0° emission for mixed DFB device samples (Nos. 4, 5, and 6 in Table 1) with ratios of (a) 4:12, (b) 4:36, and (c) 4:200, respectively, and (d) is a graph showing the stop band width and lasing threshold as a function of the number of first-order periods in the supercell. [Figure 7] FIG. 1 is a schematic diagram of a single angle measurement system. [Figure 8] FIG. 1 is a schematic diagram of a Fourier imaging spectroscopy system. [Figure 9] 1 is an image showing the beam shape of an NL100 nitrogen laser. [Figure 10] 1 is an image showing the beam shape of a Nd:YAG laser. [Figure 11] 1 is a graph showing the UV-Visible absorption (blue line), photoluminescence (red line), and amplified spontaneous emission (dashed black line) spectra of a BSBCz:CBP (6 weight percent) film. [Figure 12]13(a) and (b) are graphs showing a comparison of the laser characteristics of five quadratic period lengths in terms of (a) lasing spectrum and (b) lasing threshold. [Figure 13] (a)-(c) SEM (scanning electron micrographs) of mixed DFB samples with a periodicity of the secondary DFB region of 4 and ratios of (a) 1:3, (b) 1:9, and (c) 1:50. [Figure 14] 13A-13C are graphs showing a summary of the oscillation thresholds of mixed DFB samples with a periodicity of the secondary DFB region of 4 and with (a) 1:3 (3 times), (b) 1:9 (3 times), and (c) 1:50 ratio (3 times). [Figure 15] FIG. 13 is a photonic band diagram of an unsampled second-order DFBOSL. [Figure 16] (a) to (c) Photonic band diagrams for one period of the second-order DFB region with different (a) 1:3, (b) 1:9, and (c) 1:50 ratios, and their 0° cropped photoluminescence spectra (right) and far-field emission patterns (bottom). [Figure 17] (a) to (c) Photonic band diagrams for 36 periods of the second-order DFB region with different (a) 1:3, (b) 1:9, and (c) 1:50 ratios, and their 0° crop photoluminescence spectra (right) and far-field emission patterns (bottom). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] The present invention will be described in detail below. Although the components of the present invention may be described below with reference to a representative embodiment and a specific example, the present invention is not limited to the embodiment and example. In this specification, a numerical range indicated as "X to Y" means a range including X and Y as the lower limit and the upper limit, respectively.

[0063] Method for improving organic semiconductor laser device The method of the present invention is a method for improving an organic semiconductor laser device having an optical resonator structure and an optical amplification layer made of an organic semiconductor, comprising the steps of: the optical resonator structure includes at least one supercell structure having a first short pitch period structure, a long pitch period structure, and a second short pitch period structure; a first short pitch period structure disposed adjacent one end of the long pitch period structure and a second short pitch period structure disposed adjacent the other end of the long pitch period structure; At least two of (i) a direction perpendicular to the grating grooves of the first short pitch periodic structure, (ii) a direction perpendicular to the grating grooves of the long pitch periodic structure, and (iii) a direction perpendicular to the grating grooves of the second short pitch periodic structure are on a straight line. (1) Stretching (WS1+WS2); (2) Shortening the work week and (3) Stretching (WS1+WL+WS2); and (4) repeating the supercell structure; At least one of WS1 is the length in a direction perpendicular to the grating grooves of the first short pitch periodic structure, WS2 is the length in a direction perpendicular to the grating grooves of the second short pitch periodic structure, and WL is the length in a direction perpendicular to the grating grooves of the long pitch periodic structure. The method of the present invention is for improving the characteristics of an organic semiconductor laser device. In one embodiment of the present invention, the method is a method for reducing the oscillation threshold. In another embodiment of the present invention, the method is a method for narrowing the diffraction angle of laser light. In one embodiment of the present invention, the method is a method for reducing the oscillation threshold and narrowing the diffraction angle of laser light. The "diffraction angle of laser light" described here means the difference in the diffraction angle of two diffracted beams that are closest in the emission direction among two or more types of diffracted beams with different diffraction angles. The narrower the diffraction angle of laser light, the more the laser beam can be divided, and the more useful it is as a structured illumination device for detecting three-dimensional shapes. In the present invention, the "periodic structure" of the "first short pitch periodic structure", the "long pitch periodic structure", and the "second short pitch periodic structure" means a structure in which a plurality of grating grooves are arranged side by side at a constant pitch. Hereinafter, the convex portion between adjacent grating grooves is referred to as a "ridge". The periodic structure may be a lattice in which a plurality of convex portions and a plurality of lattice grooves are alternately arranged at a constant pitch. In the present invention, the "pitch" in the "first short pitch periodic structure", the "long pitch periodic structure", and the "second short pitch periodic structure" means the distance between the side surfaces of adjacent lattice grooves. In each supercell structure, the "long pitch periodic structure" is a periodic structure having a longer pitch than the "first short pitch periodic structure" and the "second short pitch periodic structure".

[0064] For a description of the organic semiconductor laser device used in the present invention, please refer to the description in the above paragraph "Organic Semiconductor Laser Device."

[0065] FIG. 1 shows an optical resonator structure 10 having three or more supercell structures as an example of an optical resonator structure used in the present invention. However, the configuration of the optical resonator structure usable in the present invention is not limited to this example. In FIG. 1, "FSP" indicates a first short pitch periodic structure, "LP" indicates a long pitch periodic structure, and "SSP" indicates a second short pitch periodic structure. In the optical resonator structure 10, the distance Λ1 between the side surfaces of adjacent grating grooves 1a and 1b corresponds to the pitch of the first short pitch periodic structure FSP, the distance ΛL between the side surfaces of adjacent grating grooves 3a and 3b corresponds to the pitch of the long pitch periodic structure LP, and the distance Λ2 between the side surfaces of adjacent grating grooves 2a and 2b corresponds to the pitch of the second short pitch periodic structure SSP. In the optical resonator structure 10, the direction indicated by the arrow x is perpendicular to the grating grooves, the length of the first short pitch periodic structure FSP in the x direction corresponds to WS1, the length of the long pitch periodic structure LP in the x direction corresponds to WL, and the length of the second short pitch periodic structure SSP in the x direction corresponds to WS2.

[0066] In each supercell structure, a first short pitch period structure is disposed adjacent one end of the long pitch period structure and a second short pitch period structure is disposed adjacent the other end of the long pitch period structure. The first short pitch period structure may be adjacent to one end of the long pitch period structure and the second short pitch period structure may be adjacent to the other end of the long pitch period structure.

[0067] In each supercell structure, at least two of (i) the direction perpendicular to the grating grooves of the first short pitch periodic structure, (ii) the direction perpendicular to the grating grooves of the long pitch periodic structure, and (iii) the direction perpendicular to the grating grooves of the second short pitch periodic structure are on a straight line. The directions on a straight line may be (i) and (ii), (i) and (iii), (ii) and (iii), and (i), (ii), and (iii). All of (i), (ii), and (iii) may be on a straight line.

[0068] In each supercell structure, the pitches of the first short pitch periodic structure and the second short pitch periodic structure may be the same or different, for example, the same. The lengths WS1 and WS2 may be the same or different, for example, the same. In one embodiment of the present invention, the pitches of the first short pitch periodic structure and the second short pitch periodic structure are the same, and W1=W2 is satisfied.

[0069] The method of the present invention comprises at least one of the processes (1) to (4) above. The processes carried out in the method of the present invention may be a part or all of the processes (1) to (4). The embodiment of the method of the present invention includes the following (A) to (I). (A) A method comprising carrying out (1). (B)(2). (C) A method that includes carrying out (3). (D)(4). (E) A method comprising carrying out (1) and (2). (F) A method comprising carrying out (1) and (3). (G) A method comprising carrying out paragraphs (2) and (3). (H) A method comprising carrying out (1), (2), and (3). (I) In any one of the embodiments (A) to (H), the method further comprises carrying out (4).

[0070] In the methods of the present invention, (WS1+WS2) / WL is adjusted to, for example, 4 or more, 10 or more, 50 or more, 90 or more, 150 or more, or 800 or more.

[0071] In the method of the present invention, (WS1+WS2) is adjusted to, for example, 1 μm or more, 4 μm or more, 10 μm or more, 40 μm or more, or 200 μm or more.

[0072] In the method of the present invention, the WL is adjusted to, for example, 10 μm or less, 2 μm or less, or 0.6 μm or less.

[0073] In the method of the present invention, (WS1+WL+WS2) is, for example, 2 μm or more, 5 μm or more, 20 μm or more, 50 μm or more, or 250 μm or more.

[0074] In the method of the present invention, the number of supercell structures in the optical resonator structure is, for example, 4 or more, 6 or more, 8 or more, or 10 or more.

[0075] In the method of the present invention, the pitches of the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure may be set to satisfy the Bragg condition shown in the following formula (1). In one embodiment of the present invention, the first short pitch periodic structure and the second short pitch periodic structure are each a first-order grating in which m in formula (1) is 1, and the long pitch periodic structure is a second-order grating in which m in formula (1) is 2.

[0076] Method for designing, evaluating, or manufacturing an organic semiconductor laser device Embodiments of the method of the present invention include a method for designing an organic semiconductor laser device, a method for evaluating an organic semiconductor laser device, and a method for manufacturing an organic semiconductor laser device.

[0077] In the method for designing an organic semiconductor laser device, by carrying out at least one of the above (1) to (4), it is possible to design an organic semiconductor laser device having a low oscillation threshold and a narrow diffraction angle of laser light.

[0078] In the method for evaluating organic semiconductor laser devices, by evaluating more highly an organic semiconductor laser device that satisfies at least one of the following four conditions: (1') (WS1+WS2) is longer, (2') WL is shorter, (3') (WS1+WL+WS2) is longer, and (4') the number of supercell structures is greater, it is possible to select an organic semiconductor laser device having a low oscillation threshold and a narrow diffraction angle of laser light from among two or more organic semiconductor laser devices.

[0079] In the method for manufacturing an organic semiconductor laser device, by carrying out at least one of the above (1) to (4), it is possible to manufacture an organic semiconductor laser device having a low oscillation threshold and a narrow diffraction angle of laser light. For an explanation of these methods of the present invention and the conditions used in the methods, please refer to the description in the above paragraph "Method for improving an organic semiconductor laser device."

[0080] program The program of the present invention is a program for executing the method of the present invention. That is, the program of the present invention is a program for causing a computer to execute each process in the method of the present invention. For an explanation of the method of the present invention, please refer to the descriptions in the above paragraphs "Method for improving an organic semiconductor laser device" and "Method for designing, evaluating, or manufacturing an organic semiconductor laser device".

[0081] The program of the present invention may be recorded on a computer-readable recording medium. The recording medium includes, for example, a magnetic recording medium, an optical recording medium, and a semiconductor memory. Specifically, the recording medium includes, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM (read-only memory), a CD-R, a DVD-ROM, a magnetic tape, a non-volatile memory card, a ROM, an EEPROM, and a silicon disk.

[0082] computer The computer of the present invention is a computer that executes the method of the present invention. That is, the computer of the present invention is a computer that includes a means for executing each process in the method of the present invention. For an explanation of the method of the present invention, please refer to the descriptions in the above paragraphs "Method for improving an organic semiconductor laser device" and "Method for designing, evaluating, or manufacturing an organic semiconductor laser device".

[0083] The means provided in the computer of the present invention include, for example, a calculation means for calculating the formulas in (1') and (3') above, and a screening means for selecting an organic semiconductor laser device that satisfies the above (1') to (4') from a plurality of devices based on the calculated values ​​of (1') and (3') and the numerical values ​​of (2') and (4').

[0084] Organic semiconductor laser device The organic semiconductor laser device of the present invention is an organic semiconductor laser device including an optical resonator structure and an optical amplification layer made of an organic semiconductor, the optical resonator structure includes at least one supercell structure having a first short pitch period structure, a long pitch period structure, and a second short pitch period structure; a first short pitch period structure disposed adjacent one end of the long pitch period structure and a second short pitch period structure disposed adjacent the other end of the long pitch period structure; At least two of (i) a direction perpendicular to the grating grooves of the first short pitch periodic structure, (ii) a direction perpendicular to the grating grooves of the long pitch periodic structure, and (iii) a direction perpendicular to the grating grooves of the second short pitch periodic structure are on a straight line; The organic semiconductor laser device has at least one of long (WS1+WS2), short WL, long (WS1+WL+WS2), and two or more supercell structures, where WS1 indicates the length in a direction perpendicular to the grating grooves of the first short pitch periodic structure, WS2 indicates the length in a direction perpendicular to the grating grooves of the second short pitch periodic structure, and WL indicates the length in a direction perpendicular to the grating grooves of the long pitch periodic structure. For descriptions of the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure, see the examples of ranges of (WS1+WS2), WL, (WS1+WS2) / WL, and (WS1+WL+WS2), as well as the description in the paragraph "Method for improving organic semiconductor laser device" above.

[0085] The organic semiconductor laser device of the present invention may be a light-pumped organic semiconductor laser device or a current-pumped organic semiconductor laser device (organic semiconductor laser diode). The light-pumped organic semiconductor laser device has an optical resonator structure and an optical amplification layer. The current-pumped organic semiconductor laser device has a pair of electrodes, an optical resonator structure, and an organic layer including at least an optical amplification layer.

[0086] The members and layers of the current pumped organic semiconductor laser device will be described later. The description of the optical resonator structure and the optical amplification layer also applies to the optical resonator structure and the optical amplification layer of the optical pumped organic semiconductor laser device.

[0087] electrode The current-pumped organic semiconductor laser device of the present invention has a pair of electrodes. One of the electrodes may be transparent for optical output. For the electrodes, an electrode material generally used in the technical field may be appropriately selected in consideration of its work function, etc. Examples of the electrode material include, but are not limited to, Ag, Al, Au, Cu, ITO, etc.

[0088] optical cavity structure The optical resonator structure has two or more of the above supercell structures. The number of supercell structures in the optical resonator structure is, for example, 4 or more, 6 or more, 8 or more, or 10 or more.

[0089] The optical resonator structure may have two or more supercell structures such that the direction perpendicular to the grating grooves of the supercell structures is on a straight line. In one embodiment of the present invention, WS1, WL, and WS2 of the two or more supercell structures are the same. In one embodiment of the present invention, the lengths of the two or more supercell structures in the direction perpendicular to the grating grooves are set randomly. An example of an optical resonator structure that can be used in the present invention and has the above-mentioned random supercell length is shown in FIG. 2. The optical resonator structure shown in FIG. 2 has three types of supercell structures SC1, SC2, and SC3 that have different lengths in the direction perpendicular to the grating grooves, and these three types of supercell structures are randomly arranged. Here, the lengths of the three types of supercell structures are expressed by the following formula: WL1=30Λ1+6Λ2+30Λ1 WL2=20Λ1+5Λ2+20Λ1 WL3=8Λ1+3Λ2+8Λ1 Here, WL1, WL2, and WL3 are the lengths in a direction perpendicular to the grating grooves of the three types of supercell structures, Λ1 is the pitch of the first short pitch periodic structure, and Λ2 is the pitch of the second short pitch periodic structure.

[0090] Figure 3 shows the angular dependence of laser light obtained by simulating the far-field pattern of laser light from a laser device having the optical resonator structure shown in Figure 2. When the length of the supercell is not the same in each cell (random supercell length), there is no periodicity of the supercell, and therefore the laser appears at a single angle of 0 degrees. This organic semiconductor laser device can function as a laser array that emits light of the same wavelength at a single angle.

[0091] The first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure of the supercell structure each have a groove having a depth of, for example, less than 75 nm, and the depth is, for example, 20 to 70 nm.

[0092] In one embodiment of the present invention, the first short pitch period structure, the long pitch period structure, and the second short pitch period structure have a DFB (distributed feedback) structure, which is a diffraction grating structure designed to satisfy the Bragg condition of equation (1).

[0093]

number

[0094] The DFB structures of the first short pitch period structure, the long pitch period structure, and the second short pitch period structure may be selected from the group consisting of a first order DFB structure, a second order DFB structure, a third order DFB structure, and higher order DFB structures, however, in each supercell structure, the order of the DFB structure of the long pitch period structure is greater than the order of the DFB structures of the first short pitch period structure and the second short pitch period structure.

[0095] The first short pitch period structure, the long pitch period structure, and the second short pitch period structure may be made of an insulator, such as glass, silicon diode, and plastic.

[0096] In one embodiment of the present invention, the first short pitch period structure, the long pitch period structure, and the second short pitch period structure are integrally formed with the insulator.

[0097] In one embodiment of the present invention, the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure each have ridges made of an insulator periodically arranged on an insulating substrate. In this case, the ridges and the insulating substrate may be made of different insulators. For example, the ridges may be made of silicon diodes, and the insulating substrate may be made of a glass substrate. In a periodic structure having ridges periodically arranged on an insulating substrate, the surface of the insulating substrate may be exposed at the bottom of the grooves (between adjacent ridges). For the height range of the ridges, refer to the depth range of the grating grooves described above.

[0098] organic layer The organic layer includes at least a light amplifying layer made of an organic semiconductor. The organic layer may be provided on a surface of the optical resonator structure.

[0099] Light Amplification Layer in Organic Layer The organic semiconductor used in the light amplifying layer may be a compound consisting of one or more atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, and boron atoms. The compound includes, for example, a compound consisting of one or more atoms selected from carbon atoms, hydrogen atoms, and nitrogen atoms.

[0100] The light amplification layer includes at least an organic semiconductor having laser activity. The term "organic semiconductor having laser activity" used herein means an organic semiconductor capable of lasing when supplied with energy from an external source. Hereinafter, the "organic semiconductor having laser activity" will be referred to as a "laser active material."

[0101] The laser active material is, for example, a compound having at least one stilbene unit, and another example is a compound having at least one stilbene unit and at least one carbazole unit. The stilbene unit and the carbazole unit may be substituted with a substituent such as an alkyl group or may be unsubstituted. The organic semiconductor compound may be a non-polymer having no repeating unit. The molecular weight of the compound may be 1000 or less, for example, 750 or less. Specifically, the laser active material includes, for example, 4,4'-bis[(N-carbazole)styryl]biphenyl (BSBCz) (the chemical structure of which is shown in FIG. 4(d)). The light amplification layer may include two or more types of laser active materials. For example, the light amplification layer includes only one type of laser active material.

[0102] The light amplification layer may consist of only the laser active material, or may contain other organic semiconductors in addition to the laser active material. The other organic semiconductors are, for example, organic semiconductors as a base material. The base material used may be an organic compound having an excited singlet energy and an excited triplet energy, at least one of which is higher than the laser active material. As a result, the singlet excitons and triplet excitons generated in the laser active material are confined within the molecules of the laser active material, thereby lowering the oscillation threshold. However, there are cases where the laser characteristics are improved even if the singlet excitons and triplet excitons are not sufficiently confined, and the base material capable of improving the laser characteristics may be used in the present invention without any particular restrictions. The base material may be appropriately selected from known base materials, and may be an organic semiconductor having a high glass transition temperature.

[0103] When a host material is used, the amount of laser active material in the light amplification layer may be, for example, 0.1 weight percent or more, or 1 weight percent or more, and 50 weight percent or less, 20 weight percent or less, or 10 weight percent or less.

[0104] The stimulated emission light generated by the laser active material is radiated to the outside as laser light by the action of the optical resonator structure. In one embodiment of the present invention, the laser light generated from the laser active material is diffracted by the supercell structure of the optical resonator structure and radiated to the outside as diffracted light. At this time, the light radiated from the organic semiconductor laser device may include light radiated from the base material. The light generated from the laser active material may be the main component.

[0105] Other layers in the organic layer The organic layer may be formed of only a light amplifying layer, or may have one or more organic layers in addition to the light amplifying layer. The organic layer includes, for example, an electron injection layer and a hole injection layer.

[0106] The performance of the current-pumped organic semiconductor laser device tends to be better as the number of heterointerfaces of the organic layers therein is smaller, and therefore the number of organic layers is, for example, 3 or less, 2 or less, or 1. When the current-pumped organic semiconductor laser device has two or more organic layers, for example, the thickness of the light amplification layer is more than 50%, 60%, or 70% of the total thickness of the organic layers. When the current-pumped organic semiconductor laser device has two or more organic layers, the total thickness of the organic layers is, for example, 100 nm or more, 120 nm or more, or 170 nm or more, and may be 370 nm or less, 320 nm or less, or 270 nm or less. The refractive index of the electron injection layer and the hole injection layer may be smaller than the refractive index of the light amplification layer.

[0107] When an electron injection layer is provided, the electron injection layer may contain a substance that promotes electron injection into the light amplification layer. When a hole injection layer is provided, the hole injection layer may contain a substance that promotes hole injection into the light amplification layer. These substances may be organic compounds or inorganic compounds. For example, the inorganic compound of the electron injection layer may contain an alkali metal such as Cs, and the concentration of the inorganic compound in the electron injection layer may be, for example, 1 weight percent or more, 5 weight percent or more, or 10 weight percent or more, and 40 weight percent or less, or 30 weight percent or less. The thickness of the electron injection layer may be, for example, 3 nm or more, 10 nm or more, or 30 nm or more, and 100 nm or less, 80 nm or less, or 60 nm or less.

[0108] There is no particular limitation on the method for forming the light amplifying layer and other layers in the organic layer, and each layer in the organic layer may be formed by either a dry process or a wet process.

[0109] The thickness of the entire organic layer including the light amplifying layer is, for example, 80 to 350 nm, 100 to 300 nm, or 150 to 250 nm.

[0110] Other layers The organic semiconductor laser device of the present invention may be composed of only an optical resonator structure and an organic semiconductor layer, or may further include other layers. The other layers include a transparent protective layer. The transparent protective layer is provided on the organic layer on the opposite side to the optical resonator structure. The transparent protective layer has a function of protecting the organic layer.

[0111] The transparent protective layer may be formed of a substantially transparent material. Materials used for the transparent protective layer include, for example, fluorine-containing resin and sapphire glass. A laminate (fluorine-containing resin / sapphire glass) in which sapphire glass is laminated on a fluorine-containing resin applied on the surface of the organic layer may be used as the transparent protective layer. As a commercially available resin, for example, CYTOP (manufactured by AGC Chemicals Company) may be used.

[0112] In the organic semiconductor laser device of the present invention, the laser beam may be emitted from the optical resonator structure opposite the organic layer, or may be emitted from the transparent protective layer opposite the organic layer.

[0113] The organic semiconductor laser device of the present invention has an optical resonator structure having at least one of long (WS1+WS2), short WL, long (WS1+WL+WS2), and two or more supercell structures, and therefore has a low oscillation threshold. Furthermore, in one embodiment of the present invention, the organic semiconductor laser device emits split laser beams with a small difference in the diffraction angles of the diffracted beams. Therefore, the organic semiconductor laser device can be effectively used as a structured illumination device for detecting three-dimensional shapes. In this case, the difference in the diffraction angles of the two or more diffracted beams with the closest emission directions is, for example, 8° or less, 7° or less, or 6° or less.

[0114] Usefulness of organic semiconductor laser devices As described above, the organic semiconductor laser device of the present invention has a low oscillation threshold and a narrow diffraction angle of laser light, and is therefore useful as a structured illumination device for detecting three-dimensional shapes, and is useful as an in vivo sensor, a structured optical illumination device, an optical detection device, and a face authentication device.

[0115] More detailed description of the invention The present invention will now be described in more detail.

[0116] Control of the laser emission angle in laser devices is essential in optoelectronic and optical communication applications, such as optical sensing and display. In this context, we performed a study on the optical diffraction pattern of a laser beam in a 1D-DFB (one-dimensional distributed feedback) resonator sample with an organic gain medium. The grating consists of a repeating supercell with a mixed grating sample in which a primary grating surrounds a secondary grating. Experimental results show that the diffraction angle of the laser beam is very different depending on the supercell structure. Experimental and theoretical demonstrations are performed that the magnitude of the diffraction angle (θ) of the laser beam is inversely proportional to the length of the supercell. By adjusting the length of the primary and secondary regions along with the length of the supercell, the angle θ was tuned from 0.1° to 43° with different arc emission patterns. As θ decreases, i.e., as the primary region becomes longer, a large decrease in the oscillation threshold is observed, resulting in a 2.5±0.1μJ / cm2 laser with a long pulse duration of ~3.5ns. 2 The lowest oscillation threshold was obtained.

[0117] The features of the present invention will now be described in more detail with reference to the following examples.

[0118] In this example, the light diffraction patterns and lasing thresholds were studied for 1D (one-dimensional) DFB resonator samples with organic gain layers. It was found that in a state-of-the-art OSLD (organic semiconductor laser diode) with a mixed DFB structure, the light was diffracted at different angles, with the angle between the diffracted beams being 10° each (the angle between the diffracted beams is hereafter referred to as the "diffraction angle"). The characteristic arc amplified the laser emission pattern for every 10° of the diffraction angle. 14 Although the relationship between the supercell length and the diffraction angle is well established in theory, its experimental proof and potential effects such as reducing the lasing threshold have not been fully studied. Especially for organic lasers, the diffraction angle manipulation to obtain better resolution has not been performed so far. Therefore, to solve this angle problem and reduce the lasing threshold, various mixed DFB structure samples with different lengths of the primary and secondary regions along with different supercell lengths were designed and fabricated. EXAMPLES

[0119] Lattice Design The DFB structure used in this study consists of a repeating supercell with a mixed lattice, i.e. a secondary lattice sandwiched between primary lattices on either side (Figure 4). The length of the primary DFB region varies from 1,632 nm to 27,200 nm. As the organic gain medium, a guest-host system of 6 weight percent BSBCz:CBP was adopted since it provides the best lasing behavior. 15 We also use Fourier imaging spectroscopy to measure the diffraction angle of the emitted laser beam. In the DFB resonator, optical feedback is generated by the coupling of the forward and counter-propagating waves. 16 This coupling is maximized for a particular wavelength that satisfies the Bragg condition (equation (1)).

[0120] In equation (1), m is the diffraction order, λ Bragg is the Bragg resonance wavelength, and n eff is the effective refractive index of the waveguide and Λ is the grating period. For second-order gratings, m is equal to 2, and for first-order gratings, m is equal to 1. In addition, the diffraction of light by a supercell can be expressed by the Fraunhofer diffraction law:

[0121]

number

[0122] The DFB cavity consists of a repeating supercell. Each supercell consists of a secondary grating surrounded by two primary gratings. The primary and secondary DFB gratings have periods of 136 nm and 272 nm, respectively (Fig. 4(a)). The period length was determined by inspecting standard secondary DFB devices with the same device structure such as total thickness and gain medium but different period lengths, resulting in the best candidate that exhibited the lowest optical threshold (Fig. 12(b)). The primary period was then automatically defined by dividing the secondary period length by two. The empirical effective refractive index was considered to be 1.71. Three types of mixed DFBs were then constructed with four identical secondary periods (dark blue) in each supercell but with different (secondary:primary) ratios of 4:12, 4:36, and 4:200 (Fig. 4(b)). The first candidate 4:12 ratio structure was adopted in the first OSLD structure and used as the reference structure. The other candidates have longer primary lengths than the 4:12 ratio structure, which means that the supercell length is increased by the elongation of the primary area. As shown in Figure 4(b), the supercell length is 2,720 nm for the 4:12 ratio, 5,984 nm for the 4:36 ratio, and 28,288 nm for the 4:200 ratio, respectively.

[0123] Manufacture of the device To fabricate the OSL (Organic Semiconductor Laser) device, a mixed DFB was fabricated on a glass substrate on which SiO2 was sputtered to a thickness of 70 nm. First, the substrate was cleaned by ultrasonication using acetone and boiled isopropanol successively. Then, a solvent cleaning was performed followed by UV ozone treatment for 15 min. To make the SiO2 surface hydrophobic, HDMS (Hexamethyldisilazane) was spin-coated at 4000 rpm for 15 s and annealed at 120 degrees for 2 min. Then, a photoresist solution made by mixing ZEP-520A and ZEP-520A-7 (manufactured by Zeon Corporation) together in a 1:2 ratio was spin-coated on top of the substrate at 4,500 rpm for 30 s, followed by 300 rpm for 15 s and annealed at 180 degrees for 4 min. The thickness of the resulting resist layer was 50 nm. Finally, the substrate was spin-coated with Espacer (Showa Denko K.K.), an electrification dissipating material, at 1500 rpm for 30 seconds and annealed at 80°C for 4 minutes. A DFB lattice pattern was then written on the substrate using an ELS-G100 electron beam lithography system (Elionix K.K.). The chip area was 1 × 1 mm. 2 After the electron beam exposure, the grating pattern was developed in xylene solvent at room temperature for 1 min. Then, the corrugated resist layer was etched by a RIE-10NR reactive ion etching machine (manufactured by Samco Corporation). Here, first, CHF3 gas with a flow rate of 30 sccm and power of 70 W were supplied for 5 min. Then, the remaining resist layer was cleaned by supplying O2 gas with a flow rate of 70 sccm and power of 100 W for 1 min. The height of the resulting grating was estimated to be 69 ± 5 nm. As shown in Figure 13, the grating surface was confirmed using a scanning electron microscope (JSM-7900F, manufactured by JEOL Ltd.). Next, an active layer was formed on top of the glass / SiO2 grating by thermal co-deposition of BSBCz as a guest and CBP as a host with a thickness of 200 nm at 6 weight percent, and the CYTOP layer coated on the top of the device as a protective film was cured by leaving the device under vacuum for 24 hours. An overview of the OSL structure is shown in Figure 4(c).

[0124] Results and Discussion The laser properties of OSL were investigated under pulsed light excitation by an NL100 nitrogen laser (thinkSRS Inc.) with an excitation wavelength of 337 nm and a pulse duration of ∼3.5 ns. The excitation beam area was ∼2.0 × 10 -3 cm 2 The OSL was excited from above the sapphire cover glass at a direction perpendicular to the substrate surface (0°), and the emission pattern was recorded from the glass substrate side at 0° using a multichannel spectrometer (PMA-50, Hamamatsu Photonics) (Fig. 7).

[0125] Measurement of the light diffraction angle First, we confirmed the Fraunhofer diffraction for the three lattice designs by performing angle-dependent emission, i.e., by measuring the photonic band diagrams of the DFBOSL. Photonic band diagrams were measured using a Fourier imaging spectroscopy system (Fig. 8). This measurement system has an objective lens and a Fourier lens that focuses the light of multiple diffraction orders in the range of angles θ from -23° to 23°. Details of this experimental setup are described in the Supplementary Notes. We used an NL100 nitrogen laser for excitation and a polarizer that splits the light in TE mode from the light in TM mode. The measured photonic band diagrams of the mixed DFB samples with 4:12 ratio, 4:36 ratio, and 4:200 ratio are shown in Fig. 5. These photonic band diagrams show how the wavelength of optimal coupling (Bragg wavelength) varies with angle and detail the numerous bands that intersect at specific angles. In the case of the simple structure with only a quadratic grating, only two bands that intersect each other at 0° were confirmed, which has also been well documented in previous studies. 17In Figures 5(a)-5(c), the photonic bands of OSLs with 4:12, 4:36, and 4:200 ratios are shown, corresponding to supercell periods of 2,720 nm, 5,984 nm, and 28,288 nm, respectively. The spectra show the characteristic spectral and angular narrowing due to the photonic band structure. Above threshold, the angular narrowing of the laser beam occurs in the direction perpendicular to the lattice, which corresponds to a diffracted laser beam. Note that the beam shape in the direction parallel to the lattice is fan-shaped. 18 Near the lasing threshold, the photonic band diagrams of the three OSLs clearly showed multiple bands intersecting at different equidistant angles, as shown in Figures 5(a)-5(c). In the angular range of -20°<θ<+20°, it can be seen that the photonic bands intersect at different wavelengths and equidistant angles. Thus, the appearance of additional photonic bands in the OSLs is due to the addition of a second periodicity, i.e., a supercell period, which results in Fraunhofer diffraction (an example of photonic bands in a single periodic structure is shown in Figure 15). The angle between the two diffracted beams satisfied the Fraunhofer law (Eq. 2), and at each intersection of the photonic bands, a photonic stop band was found. At the band edges of this photonic band gap, lasing occurred due to the high Q factor at the band edges, as reported in previous literature. 19 It can be confirmed that the angle between the two laser beams is inversely proportional to the length of the supercell, as predicted by the Fraunhofer method (Eq. 2). In Table 1 (No. 4, 5, and 6), an excellent agreement between the measured angles for the diffracted laser beams in the different structures and the calculated angles using the Fraunhofer method (Eq. 2) can be seen.

[0126] [Table 1] EXAMPLES

[0127] While maintaining the ratios of 4:12, 4:36, and 4:200, mixed DFB samples with different primary DFB periods and specific secondary DFB periods (1 period and 36 periods) in each supercell were further fabricated. A summary of the experimentally calculated diffraction angles is shown in Table 1 (Nos. 1, 2, and 3 (1 period) and 7, 8, and 9 (36 periods)), and the photonic band diagrams are shown in Figs. 16 and 17. According to the table, a trend of narrowing of the diffraction angle can be confirmed in each comparison with the extension of the supercell length, and the diffraction angle converges to a minimum value of 0.1° in No. 9. Here, the diffraction angle is controlled by the length of the primary and secondary DFB regions along with the supercell length. As an example, the 1:3, 1:9, and 1:50 ratios shown in Table 1 (Nos. 1, 2, and 3) showed strongly separated far-field emission with very large diffraction angles (Fig. 16). On the other hand, the 36:108, 36:324, and 36:1800 ratios shown in Table 1 (Nos. 7, 8, and 9) show strongly localized far-field emission at very small diffraction angles (FIG. 17).

[0128] Measurement of OSL oscillation threshold In the photonic band diagram measurements, 4:12, 4:36, and 4:200 ratios (No. 4, 5, and 6) were determined to be the best candidates in terms of high resolution and wide angle range laser oscillation. Therefore, the oscillation threshold measurements were performed using a 0° measurement system. The oscillation threshold was determined from the measured input / output optical power characteristics of the OSLs. In Fig. 6(a), Fig. 6(b), and Fig. 6(c), the emission spectra below and above the threshold are shown for the OSLs with mixed DFB resonator samples with different primary:secondary ratios. Below the threshold, the photonic stop band widths are about 2.86, 3.89, and 4.60 nm for the 4:12, 4:36, and 4:200 ratios, respectively. The center of the photonic stop band is located at the same 465 nm for the three OSLs. In Fig. 6(d), the change in the oscillation threshold and the photonic stop band width as a function of the length of the primary region for three different ratios is shown. Interestingly, it could be clearly seen that the oscillation threshold decreases and the width of the stop band increases as the length of the primary grating area increases. As a result, the OSL with 4:200 ratio mixed DFB resonator sample has a higher lasing power than the 4:12 ratio (21.4 ± 1.1 μJ / cm). 2 ) threshold value is 8 times lower than that for 2 ), showing an 8-fold wider stop band. Note that a relatively long pulse width of ~3.5 ns was used for the excitation source. This reduction in the oscillation threshold can be attributed to the improvement in the planar optical feedback resulting from the extension of the primary grating length. The amount of optical feedback is determined by the strength of the back-Bragg scattering, which is quantified by a coupling constant. This coupling constant is proportional to the stop band width and can be explained using the coupled wave theory proposed by Kogelnik and Shank. 16 At one edge of the stop band, lasing is possible, and the width of the stop band is a measure of the feedback strength. Thus, by improving the coupling efficiency, i.e. by increasing the coupling constant by increasing the primary length, the lasing threshold can be reduced.

[0129] Below the threshold, the emission spectra showed additional features due to the Bragg dip. These features are clearly seen in the emission of the 4:12 and 4:36 OSLs. For the 4:12 OSL, a feature is seen at 450 nm. For the 4:36 OSL, features are seen at 451, 458, 473, and 481 nm, respectively. However, for the 4:200 OSL, a very faint feature is seen in the spectrum at about 460 nm, but it is difficult to distinguish due to the presence of noise in the emission spectrum. The additional features seen at different wavelengths in the 0° emission of the 4:12 and 4:36 OSLs in Figures 6(a) and 6(b) are also seen in the photonic band diagram in Figure 5. The emission spectrum at 0° angle is shown on the right side of the photonic band diagram. For the 4:12 OSL, the bands cross at three wavelengths: 435 nm, 461 nm, and 503 nm. For the latter two longer wavelengths, dips are also seen in the 0° emission spectrum due to the overlap of the dips on the emission spectrum. Similarly, for the 4:36 ratio OSL, the bands cross at four wavelengths, 447, 461, 478, and 498 nm, and dips are also seen in the 0° emission spectrum due to the overlap of the dips on the emission spectrum. For the 4:200 ratio, multiple dips are seen in the photonic band diagram due to multiple points where the photonic bands cross. These dips introduce additional features due to the crossing of the photonic bands at different wavelengths in addition to different angles. The additional dips have a higher lasing threshold than the main stop band that satisfies the Bragg condition, simply because the gain material, BSBCz doped film, has a maximum gain around the Bragg wavelength and a lower gain at the assumed lasing wavelength away from this wavelength. Also, judging from the trend of the diffraction angle, even smaller diffraction angles and lower thresholds can be expected with longer supercell lengths of the DFB. In essence, to obtain a low threshold, the diffraction angle is controlled with the length of the supercell by stretching the primary DFB region and providing the optimum number of periods in the secondary DFB region.

[0130] conclusion In order to control the threshold and diffraction angle of organic lasers based on the Fraunhofer method, mixed DFB OSL samples were designed and studied. First, the supercell length was controlled by changing the secondary:primary ratio of the mixed DFB samples. In total, nine different DFBs were fabricated and tested. According to the measurement results of the angle-dependent emission, the laser diffraction angle was adjusted from 0.1° to 43°. This adjustment is in accordance with the Fraunhofer method (diffraction angle is inversely proportional to the supercell length), and the experimentally obtained diffraction angle shows good agreement with the calculated value. Among the nine DFBs, the structures with 4:12, 4:36, and 4:200 ratios showed wide-angle range and low-diffraction-angle emission. Therefore, these mixed DFB samples with 4:12, 4:36, and 4:200 ratios were selected for further measurement of the optically pumped oscillation threshold. The oscillation threshold was 2.5±0.1 μJ / cm when the primary DFB area was increased. 2 The photonic band gap (stop band) is wider as the primary region and the supercell length with it are longer in the 0° emission spectrum, which means stronger lateral feedback. As a result, it provides useful information on how to control the optical diffraction angle of OSL / OSLD at a low threshold without using large diffractive optical elements, which enables various applications such as in-vivo sensing devices, face recognition technology using 2D and 3D structured light, and ToF systems.

[0131] supplementary explanation Section 1: Construction of the measurement system and preparation of the device (a) Preparation of the laser characteristics measurement system In this example, two types of measurement systems were constructed: a single-angle measurement system and a Fourier imaging spectroscopy system. The former was designed to measure the optical threshold and lasing spectrum by orthogonal (0°) emission from the DFB laser device. The excitation laser source was an NL100 nitrogen laser (Think SRS Inc., wavelength 337 nm and pulse width 3.5 ns) or a Nd:YAG laser (wavelength 355 nm and pulse width 0.9 ns). Three adjustable density ND filters were used to closely control the power of the excitation source and draw the optical threshold graph. A sharp circular beam shape was formed by roughly filtering the excitation light with an aperture. Finally, a 355 nm cutoff filter was placed behind the sample and in front of the PMA50 detector to cut the source light that would interfere with the detection of light from the device.

[0132] Conversely, the latter was designed to collect and capture angle-dependent PL (photoluminescence) images widely. The excitation laser source was an NL100 nitrogen laser, the same as the single-angle measurement system. Finally, lenses were used to cut the excitation light into a circle and control the size of the source beam. Then, an objective lens, a Fourier lens, and a tube lens were arranged to collect the dispersively emitted light widely from the DFB device and send the light to a Shamrock500i spectrometer (Andor Technology). A UV cut filter was arranged to cut the nitrogen excitation laser, and finally, a polarizer was arranged to filter the output laser to 0° or 90°. In this study, the polarizer was basically set to perform 0° filtering and then 90° polarization, and the intensity of the light was very small and was removed from the image. As the acquisition settings, an exposure time of 0.2 seconds was set.

[0133] (b) Profile of the excitation laser source The beam shape of the excitation source at the same position was imaged by a WinCamD-LCMCCD camera (Optoscience) to determine the excitation area on the DFB. In this study, the sizes of the nitrogen laser and the Nd:YAG laser were measured. In the following figures, top and oblique views are shown, and two profiles of the x and y axes are shown in the top view. The approximate value of each profile was obtained by Gaussian fitting, and the peak of 13.5% was considered as the criterion for determining the width of the profile. Both types of laser sources have an elliptical beam shape, and each axis was controlled so as not to exceed 1000 nm, which is the DFB size width designed in this example.

[0134] (c) Absorbance, PL, and ASE of 6 wt. percent BSBCz:CBP thin film. Considering the consistency of optical properties, thin films were formed by thermal co-evaporation system. This procedure requires parameters such as film thickness, Abs (UV-Vis Absorption) spectrum, PL (Photoluminescence) spectrum, ASE (Amplified Spontaneous Emission) spectrum, and PLQY (Photoluminescence Quantum Yield). Firstly, the film thickness was measured by DektakXT stylus profiler (Bruker) and was 202±2 nm. The peak wavelength of the ASE spectrum was adopted in estimating the doping ratio because the wavelength shifts according to the molecular weight ratio of the host and guest materials. Secondly, Abs and PL spectra were recorded by LAMDA950 (PalkinElmer) and FluoroMax-4 (Horiba, Ltd.), respectively (Figure 11). Thirdly, the estimated ASE wavelength of the 6 weight percent film was 465 nm, and this parameter was measured by PMA50 (Hamamatsu Photonics). Finally, the PLQY of the film was measured using a QuantaurusQY (Hamamatsu Photonics) and was found to be 93% at an excitation wavelength of 330 nm.

[0135] (d) Optimization of the period of the mixed DFB resonator For simple comparison, only the second-order DFB was utilized to optimize the period length of the grating. The following five second-order period length candidates were selected: 260 nm, 264 nm, 272 nm, 276 nm, and 280 nm. All candidates had the same duty ratio of 0.5. To determine the best one, all of the second-order DFB devices with BSBCz:CBP film (6 weight percent, 200 nm thick) deposited on the DFB were fabricated and their oscillation spectra and thresholds were measured. Note that in this experiment, a Nd:YAG laser was used as the excitation source. In Figure 12(a), the oscillation spectra of the devices with each DFB candidate are shown in addition to the ASE spectrum of the BSBCz:CBP film without DFB. In all of these five oscillation spectra, a very narrow FWHM (full width at half maximum) of 0.14-0.16 nm was observed compared to the wide FWHM of the ASE spectrum of 7.20 nm. Among these candidates, the device with a second-order periodic length (Λ) of 272 nm is considered to have the lowest optical threshold because of the maximum overlap with the ASE spectrum, which means it will exhibit the best gain effect in the DFB cavity. This is verified by the measurement and comparison of the oscillation thresholds shown in Fig. 12(b). Therefore, the supercell length of the mixed DFB sample in this study was determined based on the optimal periodic length, i.e., a second-order period of 272 nm and a first-order period of 136 nm.

[0136] (e) SEM image of the DFB structure To compare the structural differences, the primary and secondary periodic lengths were fixed at 136 nm and 272 nm, respectively. Then, three different structures with the same 4 secondary lattice periods in each supercell but different supercell lengths were obtained by SEM (scanning electron microscope). Gold sputtering was performed in advance with a power of 40 mA for 60 seconds to increase the conductivity of the SiO2 lattice surface. In Figure 13(a), Figure 13(b), and Figure 13(c), the morphology of the mixed lattice samples with 1:3, 1:9, and 1:50 ratios, respectively, are shown. Additional mixed DFB samples described in the last section of the paper (1 and 36 periods in the secondary DFB region, as well as different ratios (1:3, 1:9, and 1:50)) were fabricated under the same conditions on the same day.

[0137] Section 2: Details of the main experiment (a) Measurement of emission spectrum at 0° Each output light was recorded by a single angle measurement system with PMA software (Figure 7) manufactured by Hamamatsu Photonics. The software setting parameters for data acquisition included two factors: exposure time 200 ms and averaging 5 times per frame. In the first step, the excitation laser beam size at the sample position was measured and imaged as described in section 1(b). Then, the area of ​​the ellipse was calculated by the formula: cm 2 The beam area was calculated in units of 1000 nm. Then, the sample was placed in the beam size imaging position and a wavelength-power (counts) measurement was performed. During the measurement, the excitation laser power was increased by gradually switching the densities of the neutral density filters until the output power count peak saturation. Then, each frame imaged with different densities of neutral density filters was recorded. Finally, the sample was replaced with a nanojoule meter (Ophir Photonics) and all excitation powers used were recorded (in μJ).

[0138] In the next step, all the captured data was collected and graphed to represent the oscillation threshold (Fig. 14). The graph includes three coefficients: excitation intensity (x-axis), normalized emission intensity (y-axis), and FWHM (second y-axis). First, each excitation intensity point was expressed by the following equation (3).

[0139]

number

[0140] [Table 2]

[0141] [Table 3]

[0142] (b) Fourier imaging spectroscopy of mixed DFB laser samples with only one or 36 second-order gratings in each supercell. In addition to the main experiment on mixed DFBs with different ratios and the period of the secondary DFB region is 4, DFBOSLs with different ratios (1:3, 1:9, and 1:50) and the period of the secondary DFB region is 1 and 36 were also fabricated and characterized. In Figures 15 and 16, the photonic band diagrams and theoretically and experimentally obtained diffraction angles are shown. Note that the second peak (red dashed area) in the above-threshold case in Figures 16(a) and 16(b) is noise.

[0143] For comparison, a second-order DFBOSL was fabricated and measured. In Figure 15, the photonic band diagram of the OSL is shown. [Industrial Applicability]

[0144] Using the method of the present invention, it is possible to reduce the oscillation threshold of an organic semiconductor laser device and narrow the diffraction angle of the laser light of the organic semiconductor laser device. Therefore, the organic semiconductor device improved by the method of the present invention can be effectively used as a structured illumination device for detecting three-dimensional shapes. Therefore, the present invention has high industrial applicability. [Explanation of symbols]

[0145] 10 Optical cavity structure 1a,1b,2a,2b,3a,3b lattice groove FSP First short pitch period structure LP Long pitch period structure SSP Second Short Pitch Periodic Structure References

[0146] JPEG2025502517000009.jpg193170

Claims

1. A method for improving an organic semiconductor laser device having an optical resonator structure and an optical amplification layer made of an organic semiconductor, comprising the steps of: the optical resonator structure includes at least one supercell structure having a first short pitch period structure, a long pitch period structure, and a second short pitch period structure; the first short pitch period structure is disposed adjacent one end of the long pitch period structure and the second short pitch period structure is disposed adjacent the other end of the long pitch period structure; At least two of (i) a direction perpendicular to the grating grooves of the first short pitch periodic structure, (ii) a direction perpendicular to the grating grooves of the long pitch periodic structure, and (iii) a direction perpendicular to the grating grooves of the second short pitch periodic structure are on a straight line. (1) Stretching (WS1+WS2); (2) Shortening the work week; (3) extending (WS1+WL+WS2); and (4) repeating the supercell structure; and wherein WS1 is the length in the direction orthogonal to the grating grooves of the first short pitch periodic structure, WS2 is the length in the direction orthogonal to the grating grooves of the second short pitch periodic structure, and WL is the length in the direction orthogonal to the grating grooves of the long pitch periodic structure.

2. The method of claim 1 , further comprising:

3. The method of claim 1 , further comprising:

4. The method of claim 1 , further comprising:

5. The method of claim 1 , further comprising performing (4).

6. The method of claim 1 , further comprising carrying out steps (1) and (2).

7. The method of claim 1 , further comprising carrying out steps (1) and (3).

8. The method of claim 1 , further comprising carrying out steps (2) and (3).

9. The method of claim 1 , further comprising performing steps (1), (2), and (3).

10. The method of claim 6 , further comprising performing (4).

11. The method of claim 1, wherein (WS1+WS2) / WL is adjusted to 4 or more.

12. The method of claim 1, wherein (WS1+WS2) is adjusted to 1 μm or more.

13. The method of claim 1, wherein WL is adjusted to 10 μm or less.

14. The method of claim 1, wherein (WS1+WL+WS2) is adjusted to 2 μm or more.

15. The method of claim 1 , wherein WS1=WS2.

16. 2. The method of claim 1, wherein (i) the direction perpendicular to the grating grooves of the first short pitch periodic structure, (ii) the direction perpendicular to the grating grooves of the long pitch periodic structure, and (iii) the direction perpendicular to the grating grooves of the second short pitch periodic structure are all on a straight line.

17. The method of claim 1 , wherein the first short pitch period structure abuts one end of the long pitch period structure and the second short pitch period structure abuts the other end of the long pitch period structure.

18. The method of claim 1 , wherein the periodic structure is a grating of ridges and grooves.

19. 20. The method of claim 18, wherein the first short pitch periodic structure and the second short pitch periodic structure are first-order gratings and the long pitch periodic structure is a second-order grating.

20. The method of claim 1 , which is a method for reducing an oscillation threshold.

21. 2. The method of claim 1, which is a method for narrowing the diffraction angle of laser light.

22. The method of claim 1, which is a method for lowering an oscillation threshold and narrowing a diffraction angle of a laser beam.

23. The method of claim 1 which is a method for designing an organic semiconductor laser device.

24. The method of claim 1 which is a method for evaluating an organic semiconductor laser device.

25. The method of claim 1 which is a method for manufacturing an organic semiconductor laser device.

26. A program for carrying out the method of claim 1.

27. A computer that performs the method of claim 1.

28. 26. An organic semiconductor laser device manufactured by the method of claim 25.

29. an optical resonator structure; a light amplifying layer made of an organic semiconductor; the optical resonator structure includes at least one supercell structure having a first short pitch period structure, a long pitch period structure, and a second short pitch period structure; the first short pitch period structure is disposed adjacent one end of the long pitch period structure and the second short pitch period structure is disposed adjacent the other end of the long pitch period structure; At least two of (i) a direction perpendicular to the grating grooves of the first short pitch periodic structure, (ii) a direction perpendicular to the grating grooves of the long pitch periodic structure, and (iii) a direction perpendicular to the grating grooves of the second short pitch periodic structure are on a straight line; An organic semiconductor laser device having at least one of long (WS1+WS2), short WL, long (WS1+WL+WS2), and two or more supercell structures, where WS1 is the length in the direction perpendicular to the grating grooves of the first short pitch periodic structure, WS2 is the length in the direction perpendicular to the grating grooves of the second short pitch periodic structure, and WL is the length in the direction perpendicular to the grating grooves of the long pitch periodic structure.

30. 30. The organic semiconductor laser device of claim 28, wherein the optical resonator structure has two or more supercell structures, and the two or more supercell structures are arranged such that a direction perpendicular to the lattice grooves of the supercell structures is on a straight line.

31. 31. The organic semiconductor laser device of claim 30, wherein WS1, WL, and WS2 of the two or more supercell structures are identical.

32. The organic semiconductor laser device of claim 30 , wherein the lengths of the two or more supercell structures in the direction perpendicular to the lattice grooves are set randomly.

33. 31. The organic semiconductor laser device of claim 30, wherein the optical cavity structure comprises 10 or more supercell structures.

34. 30. The organic semiconductor laser device of claim 28, wherein the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure have grooves with a depth of 75 nm or less.

35. 30. The organic semiconductor laser device of claim 28, wherein the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure have DFB (distributed feedback) structures.

36. 36. The organic semiconductor laser device of claim 35, wherein each DFB (distributed feedback) structure is selected from the group consisting of a first order DFB structure, a second order DFB structure, a third order DFB structure, and higher order DFB structures.

37. 30. The organic semiconductor laser device of claim 28, wherein the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure are made of an insulator.

38. 30. The organic semiconductor laser device of claim 28, wherein the first short pitch periodic structure, the long pitch periodic structure, and the second short pitch periodic structure comprise periodically arranged ridges of insulator on an insulating substrate.

39. 40. The organic semiconductor laser device of claim 38, wherein the ridge and the insulating substrate are made of different insulators.

40. 40. The organic semiconductor laser device of claim 38, wherein the ridge comprises a silicon diode and the insulating substrate comprises a glass substrate.

41. 40. The organic semiconductor laser device of claim 38, wherein a surface of the insulating substrate is exposed at a bottom of the groove.

42. 30. The organic semiconductor laser device of claim 28, further comprising an organic layer on a surface of the optical cavity structure.

43. 43. The organic semiconductor laser device of claim 42, further comprising a transparent protective layer on the organic layer opposite the optical cavity structure.

44. 43. The organic semiconductor laser device of claim 42 , emitting a laser beam from an opposite side of the optical cavity structure from the organic layer.

45. 44. The organic semiconductor laser device of claim 43, emitting a laser beam from the side of the transparent protective layer opposite the organic layer.

46. 30. The organic semiconductor laser device of claim 28, which emits two or more types of diffracted light having different diffraction angles.

47. 47. The organic semiconductor laser device according to claim 46, wherein a difference in diffraction angle between the two or more types of diffracted light beams having the closest radiation direction is 8[deg.] or less.

48. 30. The organic semiconductor laser device of claim 28, wherein the organic layer comprises an organic compound having at least a stilbene unit.

49. 30. The organic semiconductor laser device of claim 28, wherein the organic layer comprises 4,4'-bis[(N-carbazole)styryl]biphenyl (BSBCz).

50. The organic semiconductor laser device of claim 28, wherein the organic layer has a thickness of 80 to 350 nm.

51. comprising the organic semiconductor laser device of claim 28; The device is selected from the group consisting of an in vivo sensing device, a structured optical illumination device, an optical detection device, and a facial recognition device.

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