Laser oscillator, optical communication system with the same, laser device, laser processing device, optical power supply system, and distance measurement system

Abstract

To provide a laser oscillator capable of propagating a coupled laser beam for a long distance without using an optical fiber under an environment such as in the water.SOLUTION: A laser oscillator 50 comprises a laser diode 20 including a plurality of emitters 21 each emitting a laser beam LBE, a diffraction grating 22 and a partial reflection mirror 24. A plurality of laser beams LBE is incident to the diffraction grating 22 at mutually different angles. The partial reflection mirror 24 reflects a part of the laser beams LBE to the diffraction grating 22, and an external resonator is constituted between a rear end face of the emitter 21 and the partial reflection mirror 24. The diffraction grating 22 couples the plurality of laser beams LBE into one laser beam LB. The coupled laser beam LB is transmitted through the partial reflection mirror 24 and emitted. A wavelength region of the coupled laser beam LB is 380 nm or more to 460 nm or less.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a laser oscillator, and an optical communication system, a laser device, a laser processing device, an optical power supply system, and a distance measuring system that include the laser oscillator. [Background technology]

[0002] Conventionally, a wavelength-combined beam system using a semiconductor laser element is known (see, for example, Patent Document 1).

[0003] In the conventional configuration disclosed in Patent Document 1, an external resonator is constructed using a laser diode bar having multiple emitters that emit laser beams of different wavelengths. The laser beams emitted from the multiple emitters are wavelength-combined so that their optical axes coincide with each other, thereby obtaining a high-power combined laser beam. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5981855 Summary of the Invention [Problem to be solved by the invention]

[0005] Optical communication systems using laser light have been widely used. Various technologies for multiplexing transmitted light have been proposed to increase the amount of information that can be transmitted. For example, wavelength division multiplexing (WDM) technology combines light beams of different wavelengths in a multiplexing device and transmits the combined light through optical fiber, thereby reducing the number of optical fiber beams used as transmission paths.

[0006] However, in recent years, underwater optical communication technology has been developed. With this technology, for example, optical communication using laser light is performed between an optical receiver installed on the seabed and an optical transmitter located on the sea surface. In this case, if laser light is transmitted using optical fiber, as in conventional optical communication systems, installing a communication cable with optical fiber requires a great deal of cost. Furthermore, since the communication cable must be laid from the seabed to the sea surface, the influence of tidal currents and other factors greatly restricts the locations where the communication cable can be installed.

[0007] The present disclosure has been made in consideration of the above points, and its purpose is to provide a laser oscillator that enables long-distance propagation of coupled laser light in an environment such as underwater without using optical fiber, and an optical communication system, a laser device, a laser processing device, an optical power supply system, and a ranging system that are equipped with the same. [Means for solving the problem]

[0008] In order to achieve the above object, the laser oscillator according to the present disclosure includes a plurality of semiconductor laser devices, each having a plurality of emitters that emit laser light, an optical coupling element, and a partial reflection mirror, wherein the plurality of laser light beams are incident on a light incident surface of the optical coupling element at angles different from each other, and the partial reflection mirror reflects a portion of the laser light beams toward the optical coupling element, thereby forming an external resonator between the emitters and the partial reflection mirror, and the optical coupling element combines the plurality of laser light beams into a single combined laser beam, which passes through the partial reflection mirror and is emitted to the outside, and the wavelength range of the combined laser beam is in the range of 380 nm or more and 460 nm or less.

[0009] The optical communication system according to the present disclosure is characterized by including at least the laser oscillator and a photoreceiver that receives the combined laser light.

[0010] The laser device according to the present disclosure is characterized by including the laser oscillator and a laser head that receives the combined laser beam and emits the combined laser beam into water. [Effects of the Invention]

[0011] According to the present disclosure, long-distance propagation of coupled laser light can be achieved in environments such as underwater without using optical fibers. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating an outline of an optical communication system according to a first embodiment. [Figure 2] FIG. 1 is a schematic diagram showing a main part of an optical communication system. [Figure 3] FIG. 1 is a functional block diagram of an optical communication system. [Figure 4] FIG. 1 is a schematic diagram of a laser oscillator. [Figure 5] FIG. 2 is a diagram showing the circuit configuration of a laser oscillator. [Figure 6] FIG. 1 is a schematic diagram for explaining a wavelength combining technique. [Figure 7] 10 is a schematic diagram showing the wavelength distribution of the light intensity of a combined laser beam; FIG. [Figure 8] FIG. 1 is a diagram showing the wavelength dependence of the extinction coefficient in water. [Figure 9] FIG. 10 is a schematic diagram of another laser oscillator. [Figure 10] FIG. 10 is a schematic diagram showing a main part of an optical communication system according to a first modification. [Figure 11] FIG. 10 is a schematic diagram showing an outline of an optical communication system according to a second modification. [Figure 12] FIG. 10 is a schematic diagram showing an outline of another optical communication system according to Modification 2. [Figure 13] FIG. 11 is a schematic configuration diagram of a laser oscillator according to Modification 3. [Figure 14] 11 is a schematic diagram showing a wavelength distribution of the light intensity of a combined laser beam according to Modification 3. FIG. [Figure 15] FIG. 10 is a schematic configuration diagram of a laser oscillator according to a fourth modification. [Figure 16] 10 is a schematic diagram showing the wavelength distribution of the light intensity of a combined laser beam according to Modification 4. FIG. [Figure 17] FIG. 11 is a schematic configuration diagram of a laser oscillator according to Modification 5. [Figure 18] 13 is a schematic diagram showing the wavelength distribution of the light intensity of a combined laser beam according to Modification 5. FIG. [Figure 19] FIG. 13 is a schematic diagram of a laser oscillator according to a sixth modification. [Figure 20] 13 is a schematic diagram showing the wavelength distribution of the light intensity of a combined laser beam according to Modification 6. FIG. [Figure 21] FIG. 10 is a functional block diagram of an optical communication system according to a second embodiment. [Figure 22] FIG. 10 is a schematic diagram showing a main part of an optical communication system according to a second embodiment. [Figure 23] 10 is a schematic diagram showing a wavelength distribution of the light intensity of the second combined laser light received by the first photodetector. FIG. [Figure 24] FIG. 13 is a schematic diagram showing a main part of an optical communication system according to a seventh modification. [Figure 25] 10 is a schematic diagram showing the position distribution of the light intensity of the second combined laser light in the second light receiver. FIG. [Figure 26] FIG. 13 is a schematic diagram showing a main part of an optical communication system according to an eighth modification. [Figure 27] FIG. 13 is a functional block diagram of a main part of an optical communication system according to a ninth modification. [Figure 28] FIG. 10 is a schematic diagram showing a main part of a laser processing device according to a third embodiment. [Figure 29] FIG. 10 is a schematic diagram showing the main parts of a distance measuring system according to a third embodiment. [Figure 30] FIG. 10 is a schematic diagram showing a main part of an optical power supply system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0014] (Embodiment 1) [Configuration of optical communication system] Fig. 1 is a schematic diagram showing an outline of an optical communication system according to embodiment 1. Fig. 2 is a schematic diagram showing a main part of the optical communication system. Fig. 3 is a functional block diagram of the optical communication system.

[0015] As shown in FIG. 1, in the optical communication system 100, optical communication is performed between a laser device 90 installed on a ship 200 at sea and a base station 210 installed underwater, using a coupled laser beam LB emitted from the laser device 90. As shown in FIGS. 1 and 2, a photoreceiver 30 that receives the coupled laser beam LB is installed in the base station 210. Alternatively, the laser device 90 may be installed in the base station 210, and the photoreceiver 30 may be installed in the ship 200. In this case, bidirectional optical communication is performed between the ship 200 and the base station 210 by an optical communication system 110 (see FIG. 21). Note that the optical communication systems 100 and 110 can be used not only in the sea but also in lakes, ponds, etc. In other words, the optical communication systems 100 and 110 are underwater optical communication systems.

[0016] As shown in FIG. 2 , the laser device 90 includes a laser oscillator 50 and a laser head 40. The configuration of the laser oscillator 50 will be described later. The laser head 40 is connected to the laser oscillator 50 and emits a combined laser beam LB emitted from the laser oscillator 50 toward the base station 210. The laser head 40 includes optical components (not shown) inside its housing. These optical components include, for example, a focusing lens that focuses the combined laser beam LB and a diverging lens that diverges the combined laser beam LB and emits it into water. The laser head 40 is hermetically sealed, and a light exit port 42 is covered with a protective glass 41. The tip of the laser head 40, including the light exit port 42, is inserted into the sea. An anti-reflection coating AR is applied to both the light entrance surface and the light exit surface of the protective glass 41, with different anti-reflection coatings AR having different properties applied to the light entrance surface, i.e., the surface in contact with air, and the light exit surface, i.e., the surface in contact with water.

[0017] 3, a power supply 60 is connected to the laser oscillator 50, and a control unit 70 is connected to the power supply 60. The control unit 70 has one or more central processing units (CPUs) and a storage unit configured with a storage device such as an SSD (solid state drive) or an HDD (hard disk drive), and the power supply 60 operates based on a control signal output from the control unit 70. A current is supplied from the power supply 60 to the laser oscillator 50, and the laser oscillator 50 emits a coupled laser beam LB.

[0018] The light receiver 30 is composed of a photoelectric conversion device such as a photodiode, and upon receiving the combined laser light LB, outputs an electrical signal corresponding to the amount of light received. The calculation unit has one or more CPUs, and converts the information contained in the combined laser light LB into an appropriate format, such as audio information or image information, based on the output signal from the light receiver 30, and outputs the converted information.

[0019] [Laser oscillator configuration] Fig. 4 is a schematic diagram of a laser oscillator. Fig. 5 is a diagram showing the circuit configuration of a laser oscillator. Fig. 6 is a schematic diagram for explaining wavelength combining technology. Fig. 7 is a schematic diagram showing the wavelength distribution of the light intensity of combined laser light.

[0020] 4, the laser oscillator 50 has a first housing 10, which houses a plurality of laser diode bars 20 and a diffraction grating (optical coupling element) 22. A light exit port 11 provided in the first housing 10 is covered with a partial reflection mirror 24. Alternatively, the partial reflection mirror 24 may be housed inside the first housing 10, and the light exit port 11 may be covered with another light-transmitting member.

[0021] 5, the laser oscillator 50 further includes a switching circuit 51. The switching circuit 51 includes multiple switches SW11, SW12, SW21, SW22, SW31, SW32, SW41, SW42, SW51, and SW52. The number of switches is not limited to this and may be changed depending on the number of laser diode bars 20. Two switches are provided for one laser diode bar 20. Although not shown, the switching circuit 51 is connected to a control unit 70, which controls the opening and closing of each switch.

[0022] As shown in FIG. 5, by appropriately switching the open / close states of multiple switches included in the switching circuit 51, current can be supplied independently to each of the multiple laser diodes 20. For example, in the example shown in FIG. 5, five laser diode bars 20 are connected in series to a power supply 60. From this state, when switch SW11 is closed and switch SW12 is opened, current is no longer supplied to the laser diode bars 20 connected to switches SW11 and SW12. On the other hand, from the state shown in FIG. 5, when switches SW11, SW21, SW31, SW41, and SW51 are closed and switches SW22, SW32, SW42, and SW52 are opened, current is supplied only to the laser diode bars 20 connected to switches SW11 and SW12. Note that the switching circuit 51 is not limited to this and may be configured using FETs (Field Effect Transistors) such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors).

[0023] As shown in FIG. 6, the laser diode bars 20 each emit a laser beam LB E The laser beam LB is emitted from a plurality of emitters 21. E The combined laser beams are wavelength-combined and transmitted through the partial reflection mirror 24 as a single combined laser beam LB, which is emitted to the outside of the first housing 10. The wavelength combining technique will be described below with reference to FIG.

[0024] As shown in FIG. 6, laser light LB emitted from each emitter 21 of the laser diode bar 20 E After being diffracted by the diffraction grating 22, the incident laser beam LB is incident on the partial reflection mirror 24. E A part of the laser light LB is transmitted through the diffraction grating 22, while the remaining part is reflected back to the laser diode bar 20. Most of this reflected back light is transmitted through the light-emitting end face of the laser diode bar 20 and reaches a reflective layer (not shown) formed on the rear end face. E is reflected by the reflective layer and is emitted again to the outside of the laser diode bar 20 from the light-emitting end face.

[0025] Laser light LB emitted from each emitter 21 of the laser diode bar 20 E Of these, only light of a wavelength (hereinafter referred to as a lock wavelength) that satisfies the diffraction condition of the diffraction grating 22 and is reflected by the partial reflection mirror 24 returns to the original emitter 21. As a result, an external resonator is formed between the reflective layer formed on the rear end face and the partial reflection mirror 24, and laser light LB is emitted from the laser diode bar 20, specifically from each of the multiple emitters 21. E will be output.

[0026] The lock wavelength of each emitter 21 is λ L , the period of the diffraction grating 22 is d, the incident angle is α, the exit angle is β, and the order is m, then the lock wavelength λ L is expressed by equation (1).

[0027] d(sinα+sinβ)=mλ L ···(1) Generally, the order of the diffraction grating is m=1.

[0028] 6, the emitters 21 are formed in each laser diode bar 20 so that the incident angle α with respect to the light incident surface of the diffraction grating 22 changes for each arrangement position of the emitters 21. In this case, the lock wavelength of the emitters 21 formed in each of the plurality of laser diode bars 20 changes stepwise from one end to the other end of the plurality of laser diode bars 20 arranged in one direction.

[0029] Note that each emitter 21 can oscillate as a laser by external resonance only when the gain wavelength intensity inherent in the emitter 21 is equal to or greater than a predetermined value. g Therefore, in the laser oscillator 50, the gain peak wavelength λ of each emitter 21 is 1 / 2. g The upper and lower limit ranges are determined by the lock wavelength λ of the emitters 21, 21 at both ends of the plurality of laser diode bars 20. L The difference Δλ L_bar The laser diode bar 20 and each emitter 21 are optically designed so that the lock wavelength λ of the emitters 21 at both ends falls within the range. L The difference Δλ L_bar varies with the distance between the laser diode bar 20 and the diffraction grating 22.

[0030] That is, due to external resonance occurring between the rear end face of the emitter 21 and the partial reflection mirror 24, the laser light LB emitted from each of the multiple emitters 21 and incident on the light incident surface of the diffraction grating 22 is E The laser beams LB emitted from the emitters 21 of the laser diode bars 20 have different wavelengths. E The positional relationship between the laser diode bars 20 and the diffraction grating 22 is defined so that the optical axes of the laser beams LB 1 and LB 2 are overlapped with each other when they pass through the diffraction grating 22. E The laser beams LB travel in such a way that they overlap each other when they are incident on the partial reflection mirror 24. Eare superimposed to generate a high-power combined laser beam LB.

[0031] In addition, laser light LB with different wavelengths E are wavelength-combined, the combined laser light LB has a gain peak wavelength λ of each emitter 21 as shown in FIG. g The light intensity has a peak at a wavelength corresponding to the gain peak wavelength λ of each emitter 21 so that the wavelength range of the coupled laser light LB in this embodiment is in the range of 380 nm or more and 460 nm or less. g has been adjusted.

[0032] [Effects, etc.] As described above, the laser oscillator 50 according to this embodiment emits the laser light LB E The laser diode bar 20 has a plurality of emitters 21 emitting a light beam, a diffraction grating 22, and a partially reflecting mirror 24.

[0033] Multiple laser beams LB E The laser beam LB is incident on the diffraction grating 22 at different angles. E By reflecting a part of the light toward the diffraction grating 22, an external resonator is formed between the rear end face of the emitter 21 and the partial reflection mirror 24.

[0034] The diffraction grating 22 reflects a plurality of laser beams LB E into a single combined laser beam LB. The combined laser beam LB passes through the partial reflection mirror 24 and is emitted to the outside of the laser oscillator 50. The wavelength range of the combined laser beam LB is in the range of 380 nm or more and 460 nm or less.

[0035] By configuring the laser oscillator 50 in this manner, the gain peak wavelength λ of each emitter 21 g This allows the emission of coupled laser light LB having a distribution with a peak in optical intensity at a wavelength corresponding to the wavelength of the laser light LB. This makes it possible to realize a wavelength division multiplexing optical transmitter that can multiplex and transmit signals on multiple channels.

[0036] A conventional wavelength division multiplexing optical transmitter, for example, prepares a plurality of semiconductor laser elements, and inputs the laser light emitted from each of them into a wavelength multiplexing device to generate laser light similar to that shown in Fig. 7. In this case, the wavelength multiplexing device wavelength-converts each laser light to have a different wavelength, and the wavelength-converted laser lights are multiplexed by a multiplexing device before being transmitted to an optical fiber.

[0037] In this case, however, the wavelength division multiplexer is made up of a plurality of wavelength converters and multiplexers, which increases the size of the wavelength division multiplexer and the cost.

[0038] In addition, an example has been proposed in which a wavelength converter is omitted by preparing multiple semiconductor laser elements that emit laser light of different wavelengths, but such semiconductor laser elements require changing the structure and composition of the active layer and cladding layer, which requires labor and cost to prepare the semiconductor laser elements. Furthermore, the wavelength of the laser light emitted from the obtained semiconductor laser element often deviates from the designed value, which may prevent the desired signal from being transmitted.

[0039] On the other hand, according to this embodiment, laser diode bars 20 having the same structure and composition of the active layer and cladding layer are prepared, and the positional relationship between the plurality of laser diode bars 20, the diffraction grating 22, and the partial reflection mirror 24 is set so as to satisfy a predetermined external resonance condition. Also, the interval between the emitters 21 and the period d of the diffraction grating 22 are set. In this way, mutually different gain peak wavelengths λ can be easily and reliably obtained. g A plurality of laser beams LB having E This makes it possible to easily realize a wavelength division multiplexing optical transmitter.

[0040] Furthermore, by setting the wavelength range of the coupled laser light LB to be in the range of 380 nm or more and 460 nm or less, the loss of the coupled laser light LB in water can be reduced. This makes it possible to transmit the coupled laser light LB over long distances. This will be further explained.

[0041] Fig. 8 is a graph showing the wavelength dependence of the extinction coefficient in water. The graph shown in Fig. 8 shows data in highly transparent water.

[0042] Generally, when light enters a medium with a higher refractive index than the atmosphere, part of the light is reflected and the rest is refracted and travels through the medium. In this case, if the medium is water, the light traveling through the water is attenuated by absorption and scattering by the water.

[0043] If the light intensity just before entering the water is I0, the light intensity after traveling a distance L in the water is I, and the extinction coefficient of water is c, then the relationship shown in equation (2) holds.

[0044] I / I0=e -cL ···(2) Furthermore, if the absorption coefficient of water is a and the total scattering coefficient is b, the relationship shown in equation (3) holds.

[0045] c=a+b (3) As is clear from equation (2), the smaller the extinction coefficient c, the less light is attenuated as it travels through water. In other words, the distance traveled by light of the same intensity becomes longer.

[0046] 8, in water, light in the wavelength range of 380 nm or more and 460 nm has a smaller extinction coefficient than light in other wavelength ranges. Therefore, by setting the wavelength range of the coupled laser light LB within the above-mentioned range, the coupled laser light LB can be propagated to a greater distance.

[0047] Although the extinction coefficient of the coupled laser beam LB in quartz is smaller than that in water, as mentioned above, installing a communication cable with optical fiber requires a great deal of cost. In addition, since the communication cable must be laid from the seabed to the surface, the influence of tidal currents and other factors greatly restricts the locations where the communication cable can be installed.

[0048] On the other hand, according to this embodiment, the coupled laser light LB can be propagated to a greater distance without using an optical fiber. For example, when the output of the coupled laser light LB is several hundred watts to several kW, the theoretical distance over which optical communication is possible can be approximately several hundred meters to 1 km. This eliminates the need for expensive communication cables and reduces restrictions on the location of the optical communication system 100, thereby significantly reducing the cost of constructing the optical communication system 100.

[0049] In this embodiment, the laser light LB E In the above embodiment, a plurality of laser diode bars 20 each having a plurality of emitters 21 are prepared as light sources each having an emitter 21 for emitting laser light LB. However, the present invention is not limited to this. For example, a plurality of laser diodes each having a single emitter 21 may be prepared. E A light source having an emitter 21 that emits light is sometimes called a semiconductor laser device.

[0050] In this embodiment, the diffraction grating 22 is used to reflect a plurality of laser beams LB E However, the present invention is not limited to this. For example, as shown in FIG. 9, a prism 23 may be used to combine a plurality of laser beams LB. E may be combined into one combined laser beam LB. The diffraction grating 22 and the prism 23 may be collectively called an optical combining element.

[0051] The laser device 90 according to this embodiment includes a laser oscillator 50 and a laser head 40 that receives a combined laser beam LB and emits the combined laser beam LB into water. The laser head 40 is hermetically sealed.

[0052] By configuring the laser device 90 in this manner, the coupled laser beam LB can be propagated underwater. Furthermore, since the laser head 40 is hermetically sealed, it is possible to prevent seawater from entering the interior of the laser head 40 and changing the propagation characteristics of the coupled laser beam LB inside the laser head 40. It is also possible to prevent seawater from entering the laser oscillator 50 and causing the laser oscillator 50 to malfunction.

[0053] In addition, the tip of the laser head 40 including the light exit port 42 is inserted into the sea. This eliminates the influence of disturbances such as waves on the water surface, suppressing propagation disturbance of the coupled laser beam LB in the water. Also, it is possible to suppress degradation of optical communication quality.

[0054] Furthermore, a light exit port 42 of the laser head 40 for the coupled laser beam LB is covered with a protective glass 41. An anti-reflection coating AR is provided on the light incident surface of the protective glass 41 to prevent reflection at the interface between the protective glass 41 and air, and an anti-reflection coating AR is provided on the light exit surface of the protective glass 41 to prevent reflection at the interface between the protective glass 41 and water.

[0055] By applying the anti-reflection coating AR, it is possible to prevent unwanted reflection of the coupled laser beam LB from the light-entering surface and light-exiting surface of the protective glass 41 due to the difference in refractive index between air and the protective glass 41, and between the protective glass 41 and water. This reduces the output loss of the coupled laser beam LB propagating underwater, and also suppresses degradation of optical communication quality.

[0056] Furthermore, if the reflected light returns to the laser oscillator 50 due to unwanted reflection of the coupled laser beam LB, there is a risk of the laser oscillator 50 breaking down. According to this embodiment, the risk of such a breakdown of the laser oscillator 50 can be reduced.

[0057] The optical communication system 100 according to this embodiment includes at least a laser oscillator 50 that emits a combined laser beam LB, and a photodetector 30 that receives the combined laser beam LB.

[0058] According to this embodiment, the coupled laser beam LB can be propagated to a greater distance underwater, and a wavelength division multiplexing optical transmitter can be easily realized without using an optical fiber, thereby enabling the optical communication system 100 to be constructed at a significantly reduced cost.

[0059] <Variation 1> Fig. 10 is a schematic diagram showing the main parts of an optical communication system according to Modification 1. For ease of explanation, in Fig. 10 and the following drawings, the same parts as those in Embodiment 1 are denoted by the same reference numerals, and detailed explanations thereof will be omitted.

[0060] A laser device 90 of Modification 1 shown in Fig. 10 differs from the laser device 90 of Embodiment 1 shown in Fig. 2 in that the laser oscillator 50 and the laser head 40 are connected by an optical fiber 43. By configuring the laser device 90 as shown in this modification, the movable range of the laser head 40 can be increased. This makes it possible to easily adjust the position and direction of the laser head 40, and improves the receiving sensitivity of the photodetector 30, which is an optical receiver.

[0061] <Variation 2> Fig. 11 is a schematic diagram showing an outline of an optical communication system according to Modification 2. Fig. 12 is a schematic diagram showing an outline of another optical communication system according to Modification 2.

[0062] 1, instead of installing the base station 210 on the seabed, for example, as shown in Fig. 11, an optical receiver 30 may be mounted on an underwater robot 230 that moves underwater, and an optical communication system 100 may be constructed between the ship 200 and the underwater robot 230. Furthermore, when an optical communication system 110 is constructed to perform two-way optical communication between the ship 200 and the underwater robot 230, image data acquired by an underwater camera 240 mounted on the underwater robot 230 can also be transmitted to the optical receiver 30 installed on the ship 200.

[0063] 12, a repeater 220 may be provided in the sea, and optical communication may be performed between the ship 200 and the underwater robot 230 via the repeater 220 even when the underwater robot 230 moves in the sea. In this case, a movable mirror may be provided in the repeater 220 to reflect the combined laser beam LB toward the underwater robot 230 to which it has moved. Alternatively, a photoreceiver and a laser oscillator (not shown) may be provided in the repeater 220, and when the photoreceiver of the repeater 220 receives the combined laser beam LB emitted from the laser device 90, the laser oscillator provided in the repeater 220 may transmit the combined laser beam LB to the underwater robot 230. In the latter case, the cost of the repeater 220 increases, but the underwater communication distance using the combined laser beam LB can be increased.

[0064] <Variation 3> Fig. 13 is a schematic diagram of a laser oscillator according to Modification 3. Fig. 14 is a schematic diagram showing the wavelength distribution of the light intensity of a combined laser beam according to Modification 3.

[0065] 13 differs from the laser oscillator 50 of the first embodiment in that a different power supply 60 is connected to each laser diode bar 20 by wiring 61. In other words, the laser oscillator 50 of the present modification includes a plurality of power supplies 60 that supply current to a plurality of emitters 21, and the emitters 21 connected to one power supply 60 are different from the emitters 21 connected to the other power supplies 60.

[0066] According to this modification, the laser beam LB emitted from the laser diode bar 20 for each power supply 60 E The output of the combined laser light LB can be changed. For example, as shown in FIG. 14, the optical intensity of some wavelength bands can be made higher than the optical intensity of other wavelength bands. In this way, compared to the case where the optical intensity is the same for different wavelength bands as shown in FIG. 7, not only wavelength information but also amplitude information for each wavelength band can be superimposed on the combined laser light LB and propagated. Therefore, the amount of information that can be propagated by the combined laser light LB can be increased, and the communication speed in the optical communication system 100 can be improved.

[0067] <Variation 4> Fig. 15 is a schematic diagram of a laser oscillator according to Modification 4. Fig. 16 is a schematic diagram showing the wavelength distribution of the light intensity of a combined laser beam according to Modification 4.

[0068] 15 differs from the laser oscillator 50 of the first embodiment in that it further includes a plurality of attenuators 25 arranged between the laser diode bars 20 and the diffraction grating 22. An attenuator 25 is arranged for each laser diode bar 20. In other words, the attenuators 25 are arranged between the emitters 21 and the diffraction grating 22. The attenuators 25 arranged between one emitter 21 and the diffraction grating 22 are different from the attenuators 25 arranged between another emitter 21 and the diffraction grating 22.

[0069] Each of the plurality of attenuators 25 is configured to attenuate the laser light LB E The attenuator 25 is configured to be movable between inside and outside the optical path of the light source 21. The attenuator 25 is, for example, a shutter made of a light blocking material such as metal.

[0070] According to this modification, a specific attenuator 25 is used to detect the laser light LB E By placing it in the optical path of the laser beam LB E 16, the combined laser light LB can be propagated with information in some wavelength bands thinned out. In this way, compared to the case where different wavelength bands have the same light intensity as shown in FIG. 7, the combined laser light LB can be propagated with the presence or absence of information for each wavelength band superimposed thereon. Therefore, the amount of information that can be propagated by the combined laser light LB can be increased, and the communication speed in the optical communication system 100 can be improved.

[0071] In this modification, laser diodes each having a single emitter 21 may be arranged instead of the laser diode bars 20, and an attenuator 25 may be arranged for each laser diode.

[0072] <Variation 5> Fig. 17 is a schematic diagram of a laser oscillator according to Modification 5. Fig. 18 is a schematic diagram showing the wavelength distribution of the light intensity of a combined laser beam according to Modification 5.

[0073] The laser oscillator 50 of this modification shown in FIG. 17 outputs laser light LB E 15 in that the laser oscillator 50 has a dimming pattern having a predetermined distribution in a plane intersecting with the direction of incidence of the laser beam LB. E 15 in that the dimming pattern distribution is changeable, while the dimming device 26 is fixedly disposed in the optical path of the laser beam, and differs from the laser oscillator 50 of Modification 4 shown in Fig. 15 in that the dimming pattern distribution is changeable. The dimming device 26 is, for example, a liquid crystal shutter, and the dimming pattern is changed in response to an external signal.

[0074] According to this modification, the laser light LB E By disposing the attenuator 26 having a predetermined attenuation pattern in the optical path of the laser beam LB, the laser beam LB can be blocked and attenuated more easily than in the case shown in the fourth modification. E The wavelength ranges can be set more finely. As a result, as shown in Fig. 18, the coupled laser light LB can be propagated with information in some wavelength ranges thinned out. Furthermore, compared to the case shown in Fig. 16, the wavelength ranges in which information can be thinned out can be narrowed, and the number of wavelength ranges can be increased.

[0075] According to this modification, the presence or absence of information for each wavelength band can be superimposed on the combined laser light LB and propagated, compared to the case where different wavelength bands have the same light intensity as shown in Fig. 7. Also, compared to the case shown in Fig. 15, the width and number of wavelength bands to which the presence or absence of information is assigned can be increased. This makes it possible to increase the amount of information that can be propagated by the combined laser light LB compared to the case shown in Modification 4, thereby improving the communication speed in the optical communication system 100.

[0076] If the number of emitters 21 included in the laser oscillator 50 is about 400, even if the output of the combined laser beam LB reaches 100 W, the output of the laser beam LBE emitted from each emitter 21 will be about 250 mW. Therefore, even if the attenuator 26 is made up of a liquid crystal filter, damage to the filter can be kept small.

[0077] <Variation 6> Fig. 19 is a schematic diagram of a laser oscillator according to Modification 6. Fig. 20 is a schematic diagram showing the wavelength distribution of the light intensity of a combined laser beam according to Modification 6.

[0078] 19 differs from the laser oscillator 50 of the first embodiment in that it further includes a movable reflecting mirror 27 arranged between the diffraction grating 22 and the partial reflecting mirror 24. The movable reflecting mirror 27 is rotatable around an axis perpendicular to the optical axis of the combined laser beam LB, and reflects the combined laser beam LB emitted from the light emission surface of the diffraction grating 22 toward the partial reflecting mirror 24.

[0079] According to this modification, by rotating the movable reflecting mirror 27, the wavelength range of the combined laser light LB, more specifically, the wavelength range of the plurality of laser lights LB included in the combined laser light LB, can be reduced. E The oscillation wavelength of each of these can be changed.

[0080] In the example shown in FIG. 19, when the movable reflecting mirror 27 rotates within a range of ±γ (°) from the initial position, the relationship shown in equation (1) is transformed into equation (1A) shown below.

[0081] d(sinα+sin(β±γ))=mλ L (1A) That is, as is clear from the formula (1A), by rotating the movable reflecting mirror 27, the lock wavelength λ of each emitter 21 can be adjusted. L , and thus the oscillation wavelength can be changed.

[0082] According to this modification, by disposing a movable reflecting mirror 27 in the optical path of the combined laser beam LB between the diffraction grating 22 and the partial reflecting mirror 24, the plurality of laser beams LB included in the combined laser beam LB can be E The oscillation wavelength of each of these can be changed.

[0083] As described above, bidirectional optical communication is performed in the optical communication system 110. Optical communication may also be performed between multiple devices using the repeater 220 shown in Fig. 12. In these cases, if the coupled laser beam LB emitted from one laser oscillator 50 is received by an unintended photoreceiver 30, crosstalk may occur.

[0084] According to this modification, for example, by rotating the movable reflecting mirror 27 so that the wavelength range of the coupled laser light LB shifts for each photodetector 30, crosstalk can be prevented when optical communications are performed between multiple devices, and good quality optical communications can be performed between each device.

[0085] (Embodiment 2) Fig. 21 is a functional block diagram of an optical communication system according to embodiment 2. Fig. 22 is a schematic diagram showing a main part of the optical communication system according to embodiment 2. Fig. 23 is a schematic diagram showing a wavelength distribution of the light intensity of the second combined laser light received by the first photodetector. For ease of explanation, the power supply 60, the control unit 70, and the calculation unit 80 are omitted from the illustration of each of the first optical communication system 101 and the second optical communication system 102 in Fig. 21.

[0086] The optical communication system 110 of this embodiment shown in FIG. 21 is a two-way optical communication system, and includes a first optical communication system 101 and a second optical communication system 102.

[0087] The first optical communication system 101 and the second optical communication system 102 each have a laser oscillator 50 and a photodetector 30, and specifically have the functional blocks shown in Fig. 3. The laser oscillator 50 in the first optical communication system 101 and the photodetector 30 in the second optical communication system 102 are disposed in close proximity to each other or housed in the same housing. Similarly, the laser oscillator 50 in the second optical communication system 102 and the photodetector 30 in the first optical communication system 101 are disposed in close proximity to each other or housed in the same housing.

[0088] In the first optical communication system 101, optical communication is performed by the optical receiver 30 receiving the first combined laser beam LB1 emitted from the laser oscillator 50. In the second optical communication system 102, optical communication is performed by the optical receiver 30 receiving the second combined laser beam LB2 emitted from the laser oscillator 50.

[0089] Furthermore, the light receiver 30 in this embodiment is made up of a plurality of first light receivers 31, and the operation thereof will be described below with reference to FIG.

[0090] 22, a diffraction grating (light branching element) 22A is disposed in the optical path of the second combined laser beam LB2 emitted from the laser oscillator 50. The second combined laser beam LB2 incident on the diffraction grating 22A is diffracted to form a plurality of laser beams LB E The first light receiver 31 is disposed in each optical path.

[0091] The period d of the diffraction grating 22A is the same as the period d of the diffraction grating 22 described above, and the angle of incidence of the second combined laser beam LB2 with respect to the light incident surface of the diffraction grating 22A is the same as the angle of emergence β described above. E The wavelength ranges of the plurality of laser beams LB included in the second combined laser beam LB2 emitted from the laser oscillator 50 of the second optical communication system 102 are E These wavelength ranges correspond to those of the

[0092] As is clear from this, each of the first photodetectors 31 detects the plurality of laser beams LB included in the second combined laser beam LB2. E 23. The first photoreceiver 31 receives only light in a part of the wavelength range of the second coupled laser light LB2. By adding up the output signals output from each of the multiple first photoreceivers 31 over the wavelength range of the second coupled laser light LB2, it is possible to receive all of the information contained in the second coupled laser light LB2, as shown in FIG. 23. The addition process shown in FIG. 23 is executed by the calculation unit 80 of the second optical communication system 102. Furthermore, each of the first photoreceivers 31 receives only information in a specific wavelength range of the wavelength range of the second coupled laser light LB2.

[0093] According to this embodiment, in each of the plurality of first photodetectors 31, laser light LB in a specific wavelength range within the wavelength range of the second combined laser light LB2 is detected. E Only the second coupled laser beam LB2 can be received. Since the information contained in the second coupled laser beam LB2, i.e., the transmission information, is received in a divided state by the plurality of first photoreceivers 31, optical communication can be performed in the second optical communication system 102 with the confidentiality of the transmission information enhanced. Furthermore, since the second coupled laser beam LB2 is received by the plurality of first photoreceivers 31, the influence of external disturbances and the like can be reduced, and the S / N ratio of the received information in the optical communication can be increased.

[0094] The plurality of laser beams LB split by the diffraction grating 22A E The wavelength ranges of the plurality of laser beams LB included in the second combined laser beam LB2 emitted from the laser oscillator 50 of the second optical communication system 102 are E The wavelength range may be shifted from each of the wavelength ranges.

[0095] Although not shown, the first optical communication system 101 may also have a configuration in which the photoreceiver 30 is made up of a plurality of first photoreceivers 31, and a diffraction grating 22A is disposed in the optical path of the first coupled laser beam LB1. EIn the first optical communication system 101, optical communication can be performed with increased confidentiality of transmitted information. Furthermore, since the first coupled laser beam LB1 is received by a plurality of first photoreceivers 31, the influence of disturbances and the like can be reduced, and the S / N ratio of received information in optical communication can be increased.

[0096] In this embodiment, the first combined laser beam LB1 or the second combined laser beam LB2 is divided into a plurality of laser beams LB E Although the diffraction grating 22A is used as the light branching element for branching into two beams, the present invention is not limited to this, and a prism may also be used as the light branching element.

[0097] <Variation 7> Fig. 24 is a schematic diagram showing a main part of an optical communication system according to Modification 7. Fig. 25 is a schematic diagram showing the positional distribution of the light intensity of the second combined laser beam in the second photodetector.

[0098] The optical communication system 110 of this modified example shown in FIG. 24 differs from the optical communication system 110 of the second embodiment in the following points.

[0099] First, the laser oscillator 50 in the first optical communication system 101 and the second photodetector 32 in the second optical communication system 102 are disposed in close proximity to each other and function as an integrated optical transmitter / receiver. Furthermore, although not shown, the laser oscillator 50 in the second optical communication system 102 and the second photodetector 32 in the first optical communication system 101 are disposed in close proximity to each other and function as an integrated optical transmitter / receiver.

[0100] As shown in FIG. 24, a plurality of laser beams LB emitted from a plurality of laser diode bars 20 included in the laser oscillator 50 of the first optical communication system 101 are E1 A partial transmission mirror 28 is disposed in each of the optical paths of the laser beam LB. E1 A part of the laser beams LB incident on the diffraction grating 22B is reflected toward the diffraction grating 22B, and the remaining part is incident on the second light receiver 32. E1The first and second combined laser beams LB1 are transmitted through the diffraction grating 22B, whereby they are wavelength-combined into a single first combined laser beam LB1, which then travels toward the second photodetector 32 in the first optical communication system 101.

[0101] On the other hand, the second combined laser beam LB2 emitted from the laser oscillator 50 in the second optical communication system 102 passes through the diffraction grating 22B and is divided into a plurality of laser beams LB E2 The partially transmitting mirror 28 splits the split laser beam LB E2 That is, the second photodetector 32 is located in the optical path of the plurality of laser beams LB split by the diffraction grating 22B. E2 The second photodetector 32 also receives a portion of the first coupled laser beam LB1 reflected by the partial reflection mirror 24. As is clear from the above, the diffraction grating 22B can be said to be an optical element in which the above-mentioned optical coupling element and optical branching element are integrated.

[0102] The second light receiver 32 is composed of a plurality of divided light receiving elements (not shown), for example, a plurality of photodiodes, and output signals are output from different photodiodes depending on the incident position on the light receiving surface. That is, in the second light receiver 32, light incident at different positions on the light receiving surface is received by different photodiodes. For this reason, as shown in FIG. 25 , the light intensity is calculated for each different position on the light receiving surface of the second light receiver 32 based on the output signals of the photodiodes. This calculation is performed by the calculation unit 80.

[0103] When optical communication is performed simultaneously between the first optical communication system 101 and the second optical communication system 102, the second photodetector 32 receives a plurality of laser beams LB2 branched from the second combined laser beam LB2. E2 Not only laser light LB E3 Laser light LB is also incident. E3 is a part of the reflected light mentioned above, that is, a part of the reflected light of the first combined laser beam LB1 reflected by the partial reflection mirror 24 and the laser beam LB E1 and a part of the transmitted light transmitted by the partial transmission mirror 28. In this case, the laser light LB E3becomes a kind of noise source, and the laser light LB E2 In such a case, the light receiving sensitivity of the laser beam LB2, and therefore the receiving sensitivity of the information contained in the second coupled laser beam LB2, may be reduced. In this case, when the second coupled laser beam LB2 is not being emitted, in other words, when only the first coupled laser beam LB1 is being emitted, the laser beam LB E3 25, the position distribution on the light receiving surface of the second light receiver 32 is obtained. When the first combined laser beam LB1 and the second combined laser beam LB2 are emitted simultaneously, the laser beam LB E2 Laser light LB superimposed on E3 The signal due to the laser beam LB is subtracted. E2 The optical intensity distribution of the second combined laser beam LB2 is calculated, and the information contained in the second combined laser beam LB2 is received. Note that this subtraction process is executed by the calculation unit 80 of the second optical communication system 102.

[0104] According to this modification, the laser oscillator 50 that emits the first coupled laser beam LB1 and the second photodetector 32 that receives the second coupled laser beam LB2 can be integrated into an optical transceiver. Similarly, the laser oscillator 50 that emits the second coupled laser beam LB2 and the second photodetector 32 that receives the first coupled laser beam LB1 can be integrated into an optical transceiver. These features enable the optical communication system 110 to be made smaller and less expensive.

[0105] Furthermore, when the first optical communication system 101 and the second optical communication system 102 are operated simultaneously to perform bidirectional optical communication, even if light that becomes a noise source from the first coupled laser beam LB1 or the second coupled laser beam LB2 emitted from the nearby laser oscillator 50 is incident on the second photodetector 32, it is possible to appropriately subtract this light. This makes it possible to suppress a decrease in the light receiving sensitivity of the second photodetector 32 to the first coupled laser beam LB1 or the second coupled laser beam LB2, and to increase the S / N ratio when receiving information contained in the first coupled laser beam LB1 or the second coupled laser beam LB2, thereby achieving high-quality optical communication.

[0106] Furthermore, according to this modification, the influence of ambient light can be reduced by subtraction processing even when optical communication is performed by operating only one of the first optical communication system 101 and the second optical communication system 102. This makes it possible to improve the S / N ratio when receiving information contained in the first combined laser beam LB1 or the second combined laser beam LB2, thereby achieving high-quality optical communication.

[0107] <Variation 8> FIG. 26 is a schematic diagram showing a main part of an optical communication system according to the eighth modification.

[0108] The optical communication system 110 of this modified example shown in Fig. 26 differs from the optical communication system 110 of modified example 7 shown in Fig. 24 in that the partially transmitting mirror 29 has a light collecting function. The partially transmitting mirror 29 has a curved surface so that the surface facing the second light receiver 32 acts as a collecting lens, for example.

[0109] According to this modification, the partially transmitting mirror 29 has a light collecting function, so that the laser light LB on the light receiving surface of the second light receiver 32 E3 This simplifies the subtraction process described above, further improving the S / N ratio when receiving information contained in the first coupled laser beam LB1 or the second coupled laser beam LB2, thereby achieving high-quality optical communication.

[0110] <Variation 9> FIG. 27 is a functional block diagram of a main part of an optical communication system according to the ninth modification.

[0111] The optical communication system 110 of this modified example shown in FIG. 27 differs from the optical communication system 110 of the second embodiment in the following points.

[0112] First, an optical output monitor 33 is provided in the first optical communication system 101. Like the optical receiver 30, the optical output monitor 33 is configured with a light-receiving element such as a photodiode. Also, a polarizing beam splitter 34 and a quarter-wave plate 35 are arranged in the optical path of the first coupled laser beam LB1 directed toward the optical receiver 30 of the first optical communication system 101. Although not shown, the optical output monitor 33 may also be arranged in a position similar to that shown in FIG. 27 in the second optical communication system 102, and a polarizing beam splitter 34 and a quarter-wave plate 35 may also be arranged in the optical path of the second coupled laser beam LB2 directed toward the optical receiver 30 of the second optical communication system 102.

[0113] 27 as an example, the first coupled laser beam LB1 emitted from the laser oscillator 50 of the first optical communication system 101 is linearly polarized light, and most of it is p-polarized light, but it also contains a portion of s-polarized light. When the first coupled laser beam LB1 is incident on the first surface 34A of the polarizing beam splitter 34, the p-polarized light component is transmitted through the polarizing beam splitter 34. On the other hand, the s-polarized light component is reflected by the polarizing beam splitter 34. The s-polarized light component of the first coupled laser beam LB1 reflected by the first surface 34A of the polarizing beam splitter 34 is incident on the optical output monitor 33. Because the amount of light incident on the optical output monitor 33 is proportional to the amount of light of the first coupled laser beam LB1, the output of the first coupled laser beam LB1 can be monitored based on the output signal of the optical output monitor 33. The monitoring result of the optical output monitor 33 is fed back to the controller 70, which controls the output of the first coupled laser beam LB1. For example, if the output of the first combined laser beam LB1 falls outside a predetermined allowable range, the output of the first combined laser beam LB1 is corrected so as to fall within the allowable range. Note that the ratio of the amount of light incident on the light output monitor 33 to the output of the first combined laser beam LB1 is experimentally determined in advance.

[0114] The first combined laser beam LB1 that has passed through the polarizing beam splitter 34 becomes linearly polarized light containing only p-polarized light components, and in this state enters the quarter-wave plate 35. By passing through the quarter-wave plate 35, the polarization state of the first combined laser beam LB1 changes from linearly polarized light to circularly polarized light, and it proceeds toward the optical receiver 30 of the first optical communication system 101 as circularly polarized light.

[0115] On the other hand, the second combined laser light LB2 emitted from the laser oscillator 50 of the second optical communication system 102 is incident on the quarter-wave plate 35 of the first optical communication system 101 as either circularly polarized light or randomly polarized light. If the second combined laser light LB2 is randomly polarized, it is incident on the polarizing beam splitter 34 as randomly polarized light. On the other hand, if the second combined laser light LB2 is circularly polarized, it is converted into linearly polarized light by passing through the quarter-wave plate 35. The linearly polarized second combined laser light LB2 is incident on the second surface 34B of the polarizing beam splitter 34. In this case, the second combined laser light LB2 is reflected by the second surface 34B and received by the optical receiver 30 of the second optical communication system 102.

[0116] By providing the polarizing beam splitter 34, the photoreceiver 30 does not receive the first combined laser beam LB1, but receives only the second combined laser beam LB2. In other words, a decrease in the sensitivity of the photoreceiver 30 of the second optical communication system 102 to receive the second combined laser beam LB2 is suppressed, and the S / N ratio when receiving information contained in the second combined laser beam LB2 can be increased, thereby achieving high-quality optical communication.

[0117] Furthermore, according to this modification, the first coupled laser beam LB1 or the second coupled laser beam LB2 is used for optical communication with the s-polarized component removed using the polarizing beam splitter 34. This makes it possible to improve the S / N ratio when receiving information contained in the first coupled laser beam LB1 or the second coupled laser beam LB2, thereby achieving high-quality optical communication.

[0118] According to this modification, the laser oscillator 50 in the first optical communication system 101 and the second optical receiver 32 in the second optical communication system 102 can be arranged in close proximity to each other and function as an integrated optical transceiver, as in modification 8. Also, the laser oscillator 50 in the second optical communication system 102 and the second optical receiver 32 in the first optical communication system 101 can be arranged in close proximity to each other and function as an integrated optical transceiver.

[0119] When the first optical communication system 101 and the second optical communication system 102 are operated simultaneously to perform bidirectional optical communication, even if light that becomes a noise source from the first coupled laser beam LB1 or the second coupled laser beam LB2 emitted from the nearby laser oscillator 50 is incident on the second photodetector 32, it is possible to appropriately subtract this noise. This makes it possible to suppress a decrease in the light receiving sensitivity of the second photodetector 32 to the first coupled laser beam LB1 or the second coupled laser beam LB2, and to increase the S / N ratio when receiving information contained in the first coupled laser beam LB1 or the second coupled laser beam LB2, thereby achieving high-quality optical communication.

[0120] Furthermore, according to this modification, the influence of ambient light can be reduced by subtraction processing even when optical communication is performed by operating only one of the first optical communication system 101 and the second optical communication system 102. This makes it possible to improve the S / N ratio when receiving information contained in the first combined laser beam LB1 or the second combined laser beam LB2, thereby achieving high-quality optical communication.

[0121] The laser oscillator 50 that emits the first coupled laser beam LB1 and the second photodetector 32 that receives the second coupled laser beam LB2 can be integrated into an optical transceiver. Similarly, the laser oscillator 50 that emits the second coupled laser beam LB2 and the second photodetector 32 that receives the first coupled laser beam LB1 can be integrated into an optical transceiver. These features enable the optical communication system 110 to be made smaller and less expensive.

[0122] (Embodiment 3) Fig. 28 is a schematic diagram showing a main part of a laser processing apparatus according to embodiment 3. Fig. 29 is a schematic diagram showing a main part of a distance measuring system according to embodiment 3. Fig. 30 is a schematic diagram showing a main part of an optical power supply system according to embodiment 3.

[0123] In the first and second embodiments and the first to ninth modifications, examples have been described in which the laser oscillator 50 and the laser device 90 are incorporated as components of the optical communication systems 100 and 110. However, the uses of the laser oscillator 50 and the laser device 90 described in this specification are not particularly limited to this.

[0124] For example, as shown in Fig. 28, a laser device 90 may be incorporated into a laser processing apparatus 120. In this case, laser processing is performed on a workpiece 121 placed underwater or on the bottom of the water using a combined laser beam LB emitted from the laser device 90. In the example shown in Fig. 28, a focusing optical system (not shown) is incorporated into the laser device 90, and the combined laser beam LB is irradiated onto the workpiece 121 in a focused state.

[0125] 29, a laser device 90 may be incorporated into a distance measuring system 130. In this case, a combined laser beam LB emitted from the laser device 90 is irradiated onto an object 132 located underwater or at the bottom of the water. The light reflected by the object 132 is received by a distance measuring receiver 131, and the distance between the laser device 90 and the object 132 is measured, for example, based on the time difference between the emission of the combined laser beam LB and the reception of the reflected light. In the example shown in FIG. 29, a diverging optical system (not shown) that diverges the combined laser beam LB is incorporated into the laser device 90, and the combined laser beam LB is irradiated onto the object 132 in a diverged state.

[0126] 30, a laser device 90 may be incorporated into an underwater optical power supply system 140. In this case, a power supply receiver 141 located underwater is irradiated with a coupled laser beam LB emitted from the laser device 90 to supply power. The power supply receiver 141 is provided, for example, in a drive circuit of a solar power generation panel, and includes a photoelectric conversion element such as a photodiode. The photoelectric conversion element is irradiated with the coupled laser beam LB, and power is generated by photoelectric conversion.

[0127] According to this embodiment, in the laser device 90, the laser light LB emitted from the plurality of emitters 21 Eare combined and emitted as a single combined laser beam LB. The output of the combined laser beam LB can be increased by increasing the number of emitters 21 arranged in the laser oscillator 50. Furthermore, as described above, the combined laser beam LB in the wavelength range of 380 nm to 460 nm is little attenuated in water, and the combined laser beam LB can be irradiated at high output even at deep depths.

[0128] Therefore, when the laser device 90 is applied to the laser processing apparatus 120 shown in Fig. 28, the laser processing speed can be increased and the processing time can be shortened. Also, cutting and drilling can be easily performed on a thick plate workpiece 121. Furthermore, even if the workpiece 121 is installed deep, laser processing of the workpiece 121 can be performed.

[0129] Furthermore, when the laser device 90 is applied to the distance measuring system 130 shown in FIG. 29, even if the distance measuring light receiver 131 is installed deep, the intensity of the reflected light can be ensured sufficiently, and the distance measurement accuracy can be improved.

[0130] 30, sufficient power can be supplied to the power supply receiver 141. Even if the power supply receiver 141 is installed deep, power can be supplied by irradiating it with a high-power coupled laser beam LB.

[0131] In either case, the workpiece 121, the object 132, and the power supply photoreceiver 141, which are the irradiation targets, can be irradiated with the high-power coupled laser beam LB without using an optical fiber. [Industrial Applicability]

[0132] The laser oscillator of the present disclosure can achieve long-distance propagation of coupled laser light in environments such as underwater without using optical fibers. [Explanation of symbols]

[0133] 10 First cabinet 11 Light exit port 20 Laser diode bar (semiconductor laser device) 21 Emitter 22 Diffraction grating (optical coupling element) 22A Diffraction grating (optical branching element) 22B Diffraction Grating (Optical Coupling Element / Optical Branching Element) 23 Prism 24 Partially Reflecting Mirror 25 Dimmer 26 Dimmer 27 Movable reflecting mirror 28 Partially Transmitting Mirror 29 Partially Transmitting Mirror 30 Receiver 31 1st receiver 32 2nd receiver 33 Optical Output Monitor 34 Polarizing Beam Splitter 35 1 / 4 wave plate 40 Laser Head 41 Protective Glass 42 Light exit port 43 Optical Fiber 50 Laser Oscillator 51 Switching Circuit 60 power supply 70 Control Unit 80 Arithmetic section 90 Laser Device 100 Optical Communication System 101 First Optical Communication System 102 Second Optical Communication System 110 Optical communication system (two-way optical communication system) 120 Laser processing equipment 121 Workpiece 130 Ranging System 131 Distance measuring receiver 132 Object 140 Underwater optical power supply system 141 Power supply receiver 200 ships 210 base station 220 Repeater 230 Underwater Robot 240 Underwater Camera AR Anti-Reflection Coating LB coupled laser light LB1 first coupled laser beam LB2 second coupled laser light LB E laser light

Claims

1. a plurality of semiconductor laser devices each having a plurality of emitters for emitting laser light; an optical coupling element; a partially reflective mirror; the plurality of laser beams are incident on the light incident surface of the optical coupling element at angles different from each other; the partially reflective mirror reflects a portion of the laser light toward the optical coupling element, thereby forming an external resonator between the emitter and the partially reflective mirror; the optical coupling element combines the plurality of laser beams into one combined laser beam, The combined laser beam passes through the partial reflection mirror and is emitted to the outside. A laser oscillator characterized in that the wavelength region of the combined laser light is in the range of 380 nm or more and 460 nm or less.

2. 2. The laser oscillator according to claim 1, 10. A laser oscillator, wherein the optical coupling element is a diffraction grating or a prism.

3. 3. The laser oscillator according to claim 1, The semiconductor laser device is a laser oscillator characterized in that it has a plurality of laser diodes each having one of the emitters, or one or a plurality of laser diode bars each having a plurality of the emitters.

4. 4. The laser oscillator according to claim 3, a power supply and a switching circuit for supplying current to the plurality of emitters; A laser oscillator characterized in that current can be supplied independently to each of the plurality of laser diodes or laser diode bars by switching between open and closed states of a plurality of switches included in the switching circuit.

5. 4. The laser oscillator according to claim 1, a plurality of power sources for supplying current to the plurality of emitters; 1. A laser oscillator, wherein the emitter connected to one of the power supplies is different from the emitter connected to the other of the power supplies.

6. 6. The laser oscillator according to claim 1, further comprising a plurality of attenuators disposed between the emitter and the optical coupling element; the attenuator disposed between one of the emitters and the optical coupling element is different from the attenuator disposed between the other of the emitters and the optical coupling element, 10. A laser oscillator, comprising: a plurality of attenuators each configured to be movable between within and outside the optical path of the laser light;

7. 6. The laser oscillator according to claim 3, the semiconductor laser device is one or more laser diode bars having a plurality of the emitters, further comprising a plurality of attenuators disposed between the emitter and the optical coupling element; the attenuator is provided with an attenuation pattern having a predetermined distribution in a plane intersecting with the incident direction of the laser light, A laser oscillator, wherein the distribution of the dimming pattern is changeable.

8. 8. The laser oscillator according to claim 1, a movable reflecting mirror disposed between the optical coupling element and the partially reflecting mirror; the movable reflecting mirror is rotatable around an axis perpendicular to an optical axis of the combined laser beam, and reflects the combined laser beam emitted from the light emitting surface of the optical coupling element toward the partial reflecting mirror; A laser oscillator configured so that the wavelength range of the combined laser light can be changed by rotating the movable reflecting mirror.

9. A laser oscillator according to any one of claims 1 to 8; and a photoreceiver that receives the combined laser beam.

10. 10. The optical communication system according to claim 9, an optical branching element that branches the combined laser beam into a plurality of the laser beams; The optical communication system is characterized in that the optical receiver is disposed in the optical paths of the plurality of laser beams branched by the optical branching element.

11. 11. The optical communication system according to claim 10, A plurality of the light receivers are provided, An optical communication system, wherein each of the plurality of photodetectors is disposed in the optical path of each of the plurality of laser beams branched by the optical branching element.

12. 12. The optical communication system according to claim 10, further comprising a plurality of partially transmitting mirrors arranged in the optical paths of the plurality of laser beams, the partially transmitting mirror reflects a part of the laser light emitted from the semiconductor laser device toward the optical coupling element and causes the remainder of the laser light to be incident on the optical receiver; The optical communication system is characterized in that the optical receiver further receives the plurality of laser beams branched by the optical branching element.

13. 13. The optical communication system according to claim 12, The optical communication system is characterized in that the partially transmitting mirror has a light-collecting function, and collects the remaining part of the laser light emitted from the semiconductor laser device and makes it incident on the photodetector.

14. 14. The optical communication system according to claim 12, the optical communication system is composed of a first optical communication system and a second optical communication system, the first optical communication system performs optical communication by transmitting and receiving a first coupled laser beam; the second optical communication system performs optical communication by transmitting and receiving a second coupled laser beam; the first optical communication system and the second optical communication system each include a calculation unit; the calculation unit included in the first optical communication system subtracts a light receiving signal generated by the light receiver when the second combined laser beam is incident on the optical branching element from a light receiving signal generated by the light receiver when the first combined laser beam and the second combined laser beam are incident on the optical branching element; the calculation unit included in the second optical communication system subtracts the optical reception signal generated by the optical receiver when the first combined laser beam is incident on the optical branching element from the optical reception signal generated by the optical receiver when the first combined laser beam and the second combined laser beam are incident on the optical branching element.

15. 15. The optical communication system according to claim 12, An optical communication system, wherein the optical branching element is common to the optical coupling element.

16. 10. The optical communication system according to claim 9, the optical communication system is composed of a first optical communication system and a second optical communication system, the first optical communication system includes one of the laser oscillators and one of the optical receivers, performing optical communication by transmitting and receiving a first combined laser beam emitted from one of the laser oscillators; the second optical communication system includes another of the laser oscillators and another of the optical receivers; performing optical communication by transmitting and receiving a second combined laser beam emitted from another of the laser oscillators; an optical communication system, characterized in that a polarizing beam splitter and a quarter-wave plate are disposed in the optical path of the first coupled laser beam;

17. 17. The optical communication system according to claim 16, further comprising an optical output monitor that receives a portion of the first combined laser beam reflected by the polarizing beam splitter; an optical communication system, characterized in that the output of the first coupled laser beam is controlled based on a light receiving signal of the optical output monitor;

18. 18. The optical communication system according to claim 16 or 17, the second combined laser beam passes through the quarter-wave plate and enters the polarizing beam splitter; an optical communication system, wherein the second combined laser beam reflected by the polarizing beam splitter is received by another of the optical receivers;

19. 19. The optical communication system according to claim 9, an optical communication system further comprising a laser head that receives the combined laser beam and emits the combined laser beam into water;

20. A laser oscillator according to any one of claims 1 to 8; a laser head that receives the combined laser beam and emits the combined laser beam into water.

21. 21. The laser device according to claim 20, The laser device is characterized in that the laser head is hermetically sealed.

22. 22. The laser device according to claim 20, a light exit port of the laser head for the combined laser light is covered with a protective glass; A laser device characterized in that an anti-reflection coating is provided on the light exit surface of the protective glass to prevent reflection at the interface between the protective glass and water.

23. A laser beam irradiation device comprising at least the laser device according to any one of claims 20 to 22, A laser processing device characterized by irradiating a workpiece placed underwater or on the bottom of the water with the combined laser beam to perform laser processing on the workpiece.

24. A laser device according to any one of claims 20 to 22; and a power supply receiver that is installed underwater and receives the combined laser beam.

25. A laser beam irradiation device comprising at least the laser device according to any one of claims 20 to 22, receiving reflected light of the combined laser light irradiated onto an object located underwater or on the bottom of the water; A distance measuring system, characterized in that the distance between the laser device and the object is measured based on the time difference between the emission time of the combined laser light and the reception time of the reflected light.

Images