KR102337812B1 - Apparatus and method for controlling phase modulation in coherent beam combining laser system - Google Patents

Abstract

The present invention relates to a coherent beam combining laser system controlling a phase on the basis of a stochastic parallel gradient descent (SPGD) algorithm. According to the present invention, a phase controller controls phase modulation of a signal beam by using a plurality of channels. The phase controller comprises: an analog-digital converter (ADC) converting an analog input signal related to a beam strength into a digital signal; a movement average filter filtering the digital signal with respect to the beam strength; a perturbation generator generating a perturbation signal applied to a beam corresponding to one of the plurality of channels; an SPGD operator determining a phase value for modulating a phase of the beam corresponding to one of the plurality of channels on the basis of a beam strength signal filtered by the moving average filter and the perturbation signal; and a digital-analog converter (DAC) converting a phase control signal related to a phase value into an analog signal.

Description

APPARATUS AND METHOD FOR CONTROLLING PHASE MODULATION IN COHERENT BEAM COMBINING LASER SYSTEM

The present disclosure relates generally to a coherent beam-coupled laser system, and more specifically, to a coherent beam-coupled laser system that controls the phase based on a stochastic parallel gradient descent (SPGD) algorithm for controlling the phase modulation of a laser beam. It relates to an apparatus and method.

The power improvement of a laser using a single laser is fundamentally limited by thermal problems and non-linearities in the laser gain material. In order to overcome this limitation, a beam combining method for combining multi-channel lasers has been proposed, and spectral beam combining and coherent beam combining are used. Coherent beam coupling is one of the techniques for obtaining high-intensity light energy by focusing a plurality of light sources at one location. Instructs a technique that can achieve high strength. Compared to other methods such as wavelength-beam combining, this technology can be expected to obtain the highest light intensity, so the optical system defense industry such as beam combining of ultra-short laser pulses for particle acceleration and continuous oscillation laser beam combining for directional laser energy weapons can be used in the field.

The multi-channel laser beam combining method is a method of combining beams by controlling the phase of each beam distributed to a plurality of channels. According to the prior art, for the reason that real-time phase control and the design of a phase controller from a long distance are easy, the SPGD algorithm is used. A multi-channel phase-controlled coherent beam combining method is used. However, the conventional multi-channel phase-controlled coherent beam coupling method using the SPGD algorithm fails to accurately determine the coherence beam coupling state when the beam intensity is momentarily decreased due to laser fluctuations. Accordingly, there is a need for a technique for accurately determining the coherence beam coupling state and accurately controlling the phase modulation of the multi-channel laser beams to correspond to the coherent beam coupling state.

Based on the above discussion, the present disclosure provides an apparatus and method for controlling the phase modulation of a laser beam in a coherent beam combining laser system that controls the phase based on the SPGD algorithm.

In addition, the present disclosure provides an apparatus and method for identifying a coherent beam coupling state in a coherent beam coupling laser system that controls a phase based on an SPGD algorithm.

In addition, the present disclosure provides an apparatus and method for controlling phase modulation of multi-channel laser beams to correspond to a coherent beam coupling state in a coherent beam coupling laser system that controls a phase based on an SPGD algorithm.

According to various embodiments of the present disclosure, in a coherent beam combining laser system for controlling a phase based on a stochastic parallel gradient descent (SPGD) algorithm, the phase controller for controlling the phase modulation of a signal beam using a plurality of channels is the intensity of the beam ADC (analog to digital converter) for converting an analog input signal to a digital signal, a moving average filter for filtering a digital signal for the intensity of the beam, corresponding to one of the plurality of channels A perturbation generator for generating a perturbation signal applied to a beam to be used, a phase value for modulating a phase of a beam corresponding to one of the plurality of channels based on the beam intensity signal filtered by the moving average filter and the perturbation signal It may include a SPGD operator that determines the value, and a digital to analog converter (DAC) for converting a phase control signal related to the phase value into an analog signal.

According to another embodiment, the moving average filter may be configured to filter a signal based on an average value of continuously input beam intensity values in the signal related to the beam intensity.

According to another embodiment, the moving average filter may include at least one of a simple moving average filter, a weighted moving average filter, a geometric moving average filter, and an exponential moving average filter.

According to an embodiment of the present disclosure, in a coherent beam combining laser system for controlling a phase based on an SPGD algorithm, a laser device includes an oscillator for generating a signal beam, a beam splitter for distributing the signal beam to correspond to a plurality of channels; A phase modulator that modulates the phase of the distributed signal beam, a photodetector that converts an optical signal related to the intensity of the beam output from the laser device into an electrical signal, and an analog input that relates to the intensity of the beam received from the photodetector ADC for converting a signal into a digital signal, a moving average filter for filtering the digital signal regarding the intensity of the beam, a perturbation generator for generating a perturbation signal applied to a beam corresponding to one of the plurality of channels, and the moving average filter An SPGD calculator that determines a phase value for modulating a phase of a beam corresponding to one of the plurality of channels based on the filtered beam intensity signal and the perturbation signal, and an analog phase control signal related to the phase value and a phase controller including a DAC for converting a signal, wherein the phase modulator modulates the laser phase to correspond to the phase value based on the phase control signal transmitted from the phase controller.

According to another embodiment, the moving average filter may be configured to filter the signal based on an average value of continuously input beam intensity values in the signal related to the beam intensity.

According to another embodiment, when the average value of the intensity values of the beam is less than or equal to a threshold value determined based on the moving average filter, the phase controller sets the state of the beam output from the laser device to the beam coupling release state. and when the average value of the intensity values of the beam is greater than the threshold value, the state of the beam output by the laser device may be identified as the beam coupling state.

According to an embodiment of the present disclosure, in the coherent beam combining laser system for controlling the phase based on the SPGD algorithm, the operating method of the phase controller for controlling the phase modulation of the signal beam using a plurality of channels is analog related to the intensity of the beam converting an input signal in the form of a digital signal, applying a moving average filter to the digital signal regarding the intensity of the beam, generating a perturbation signal applied to a beam corresponding to one of the plurality of channels; determining a phase value for modulating a phase of a beam corresponding to one of the plurality of channels based on the beam intensity signal filtered by the moving average filter and the perturbation signal, and phase control related to the phase value converting the signal to an analog signal.

According to another embodiment, in the method of operating the phase controller, when the average value of the intensity values of the beams continuously input in the signal related to the intensity of the beam is less than or equal to a threshold value, the state of the beam output by the laser device is beam-combined. The method may further include the steps of identifying the released state, and when the average value of the intensity values of the beam is greater than the threshold value, identifying the state of the beam output from the laser device as the beam coupling state.

Various respective aspects and features of the invention are defined in the appended claims. Combinations of features of the dependent claims may be combined with features of the independent claims as appropriate, not just expressly set forth in the claims.

In addition, one or more features selected in any one embodiment described in this disclosure may be combined with one or more features selected in any other embodiment described in this disclosure, and alternatives to these features a combination of at least partially alleviates one or more technical problems discussed in the present disclosure, or at least partially alleviates technical problems that can be discerned by a person skilled in the art from the present disclosure, and furthermore features of embodiments ( The combination is possible, provided that a specific combination or permutation so formed of the embodiment features is not understood by a person skilled in the art as incompatible.

In any described example implementation, two or more physically separate components may alternatively be integrated into a single component if their integration is possible, and the single component so formed If the same function is performed by , the integration is possible. Conversely, a single component of any embodiment described in the present disclosure may alternatively be implemented with two or more separate components that achieve the same function, where appropriate.

It is an object of certain embodiments of the present invention to solve, mitigate, or eliminate, at least in part, at least one of the problems and/or disadvantages associated with the prior art. Certain embodiments aim to provide at least one of the advantages described below.

Apparatus and method according to various embodiments of the present disclosure can accurately identify a coherent beam coupling state and accurately control phase modulation of multi-channel laser beams in a coherent beam coupling laser system that controls a phase based on an SPGD algorithm do.

Effects obtainable in the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art to which the present disclosure belongs from the description below. will be.

1 shows a laser device in a coherent beam-coupled laser system with phase control based on the SPGD algorithm.
2 illustrates a configuration of a laser device in a coherent beam combining laser system for controlling a phase based on an SPGD algorithm according to various embodiments of the present disclosure.
FIG. 3 shows the configuration of a phase controller in a coherent beam combining laser system that controls a phase based on a conventional SPGD algorithm.
4 illustrates a configuration of a phase controller in a coherent beam combining laser system for controlling a phase based on an SPGD algorithm according to various embodiments of the present disclosure.
5 shows a signal graph with respect to the intensity of a laser beam in a conventional coherent beam coupling laser system and a coherent beam coupling laser system according to various embodiments of the present disclosure.
6 is a flowchart illustrating a method of operating a phase controller in a coherent beam combining laser system for controlling a phase based on an SPGD algorithm according to various embodiments of the present disclosure.

Terms used in the present disclosure are used only to describe specific embodiments, and may not be intended to limit the scope of other embodiments. The singular expression may include the plural expression unless the context clearly dictates otherwise. Terms used herein, including technical or scientific terms, may have the same meanings as commonly understood by one of ordinary skill in the art described in the present disclosure. Among the terms used in the present disclosure, terms defined in a general dictionary may be interpreted with the same or similar meaning as the meaning in the context of the related art, and unless explicitly defined in the present disclosure, ideal or excessively formal meanings is not interpreted as In some cases, even terms defined in the present disclosure cannot be construed to exclude embodiments of the present disclosure.

In various embodiments of the present disclosure described below, a hardware access method will be described as an example. However, since various embodiments of the present disclosure include technology using both hardware and software, various embodiments of the present disclosure do not exclude a software-based approach.

Hereinafter, the present disclosure relates to a phase controller and an operating method of the phase controller in a coherent laser beam combining system. Specifically, the present disclosure relates to a coherent beam-coupled laser system using a stochastic parallel gradient descent (SPGD) algorithm. Specifically, the present disclosure describes a technique for controlling the phase modulation of a laser beam in a coherent beam-coupled laser system that controls the phase based on the SPGD algorithm.

Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art to which the present disclosure pertains can easily implement it. However, since the technical spirit of the present disclosure may be modified and implemented in various forms, it is not limited to the embodiments described herein. In the description of the embodiments disclosed in the present specification, when it is determined that a detailed description of a related known technology may obscure the gist of the present disclosure, a detailed description of the known technology will be omitted. The same or similar components are given the same reference numerals, and overlapping descriptions thereof will be omitted.

In the present specification, when an element is described as being "connected" with another element, it includes not only the case of being "directly connected" but also the case of being "indirectly connected" with another element interposed therebetween. When an element "includes" another element, it means that another element may be further included without excluding another element in addition to other elements unless otherwise stated.

Some embodiments may be described in terms of functional block configurations and various processing steps. Some or all of these functional blocks may be implemented in various numbers of hardware and/or software configurations that perform specific functions. For example, the functional blocks of the present disclosure may be implemented by one or more microprocessors, or by circuit configurations for a given function. The functional blocks of the present disclosure may be implemented in various programming or scripting languages. The functional blocks of the present disclosure may be implemented as an algorithm running on one or more processors. A function performed by a functional block of the present disclosure may be performed by a plurality of functional blocks, or functions performed by a plurality of functional blocks in the present disclosure may be performed by one functional block. In addition, the present disclosure may employ prior art for electronic configuration, signal processing, and/or data processing, and the like.

In addition, in the present disclosure, in order to determine whether a specific condition is satisfied (satisfied) or satisfied (fulfilled), an expression of more than or less than is used, but this is only a description to express an example, and more or less description is excluded not to do Conditions described as 'more than' may be replaced with 'more than', conditions described as 'less than', and conditions described as 'more than and less than' may be replaced with 'more than and less than'.

1 shows a laser device 100 in a coherent beam-coupled laser system that controls phase based on the SPGD algorithm. Hereinafter used '… wealth', '… The term 'group' means a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software.

Referring to FIG. 1 , the laser device includes an oscillator 101 , a beam splitter 103 , a phase modulator 105 , a photo detector 107 , and a phase controller 109 . The phase controller includes an analog to digital converter (ADC) 121 , a perturbation generator 123 , a phase determiner 125 , and a digital-to-analog converter 127 .

The oscillator 101 performs a function of generating a signal beam. The oscillator 101 may generate a laser beam and oscillate the generated laser beam to generate a signal beam transmitted by the laser device.

The beam splitter 103 performs a function of splitting a signal beam. The beam splitter 103 may split a signal beam using a plurality of channels for each channel. According to an embodiment of the present disclosure, the beam splitter 103 may split the signal beam received from the oscillator 101 into a plurality of signal beams corresponding to a plurality of channels.

The phase modulator 105 performs a function of modulating phases of a plurality of signal beams corresponding to a plurality of channels. The phase modulator 105 may modulate the phases of signal beams for a plurality of channels under the control of the phase controller 109 . According to an embodiment of the present disclosure, the laser apparatus 100 may include a plurality of phase modulators to correspond to each of the plurality of signal beams. The plurality of phase modulators may modulate phases of a plurality of corresponding signal beams.

The photodetector 107 performs a function of converting an optical signal related to the intensity of a beam into an electrical signal. According to an embodiment of the present disclosure, the photodetector 107 converts an optical signal related to the intensity of the beam into an electric signal in order to identify the intensity of the beam output by the laser device, and converts the converted electric signal to the phase controller ( 109) can be forwarded.

The phase controller 109 performs a function of controlling the phase modulator 105 . The phase controller 109 receives the electrical signal output by the photodetector, and determines a phase value for coherent beam coupling by using information about the intensity of the beam. The phase controller may generate a phase control signal for controlling the phase modulator using the determined phase value and transmit the phase control signal to the phase modulator.

According to an embodiment of the present disclosure, the phase controller 109 converts an analog-type input signal input using the analog-to-digital converter 121 into a digital signal. Also, the phase controller 109 may randomly generate a perturbation signal to be applied to a plurality of signal beams corresponding to a plurality of channels by using the perturbation generator 123 .

Thereafter, the phase controller 109 determines a phase value to be applied to a plurality of beams corresponding to a plurality of channels using the phase determiner 125 . The phase determiner 125 may determine a phase value to be applied to the plurality of beams from the perturbation signal and the digital signal by performing an SPGD algorithm operation. The phase control method for performing the SPGD algorithm operation is a method of finding a phase for each channel at which the intensity of a beam is maximized by measuring the intensity of a combined beam while randomly applying phase perturbation to beam signals corresponding to each of a plurality of channels. to instruct The coherent beam coupling state indicates a state in which a phase for each channel in which the intensity of a laser beam is maximized is found. In a state in which coherent beam combining has occurred, the phase controller may maintain a phase for each channel in which beam combining has occurred while repeatedly applying a low-intensity perturbation signal for each channel. According to an embodiment of the present disclosure, the phase determiner 125 uses the SPGD algorithm to apply the perturbation signals to the plurality of signal beams corresponding to the plurality of channels, respectively, based on the changing intensity of the laser beam. The phase value can be determined. Thereafter, the phase controller 109 may generate a digital phase control signal for controlling the phase modulator based on the phase value determined through an operation using the SPGD algorithm. The phase controller 109 converts the digital phase control signal into an analog phase control signal using the digital-analog converter 127 and transmits the generated analog phase control signal to the phase modulator 105 . can

2 illustrates a configuration 200 of a laser device in a coherent beam combining laser system for controlling a phase based on an SPGD algorithm according to various embodiments of the present disclosure. FIG. 2 illustrates a detailed configuration of the laser device 100 of FIG. 1 .

Referring to FIG. 2 , the configuration 200 of the laser device includes an oscillator 201 , a beam splitter 203 , first to third phase modulators 205-1 to 205-3, and first to third amplifiers. It may include amplifiers 207 - 1 to 207 - 3 , a beam combiner 209 , a beam splitter 211 , a photo detector 213 , and a phase controller 215 .

The oscillator 201, the beam splitter 203, the first to third phase modulators 205-1 to 205-3, the photodetector 213, and the phase controller 215 of FIG. The oscillator 101 , the beam splitter 103 , the phase modulator 105 , the photodetector 107 , and the phase controller 109 corresponding to the configuration may perform the same functions.

The oscillator 201 generates a laser beam and oscillates the generated laser beam to generate a signal beam transmitted by the laser device. According to an embodiment of the present disclosure, the oscillator 201 may include a master oscillator. The laser beam generated by the oscillator may be transmitted to the beam splitter 203 .

The beam splitter 203 splits a signal beam using a plurality of channels into signal beams for each channel. According to an embodiment of the present disclosure, the signal beam oscillated by the master oscillator may be divided into respective channels through the beam splitter 203 . According to an embodiment of the present disclosure, when the number of channels through which a signal beam is transmitted is three, the beam splitter 203 may split the signal beam into three beams. Correspondingly, the laser device may include three phase modulators and three amplifiers. 2 illustrates a case in which the signal beam has three channels, the number of channels may be changed according to a user's setting.

The first to third phase modulators 205 - 1 to 205 - 3 modulate a phase of each of a plurality of signal beams corresponding to a plurality of channels. According to an embodiment of the present disclosure, the first to third phase modulators 205 - 1 to 205 - 3 may modulate phases of signal beams related to a plurality of channels according to the control of the phase controller 215 . have.

The first to third amplifiers 207-1 to 207-3 amplify the phase-modulated signal in order to increase the output of the laser device. According to an embodiment of the present disclosure, the first to third amplifiers may include optical fiber amplifiers. Signal beams corresponding to each of the plurality of channels may be transmitted to the beam combiner 209 through the optical fiber amplifier.

The beam combiner 209 performs a function of combining the divided signal beams to correspond to a plurality of channels. According to an embodiment of the present disclosure, the beam combiner 209 may combine signal beams corresponding to each of the plurality of channels amplified through the optical fiber amplifier into one beam. The laser device may irradiate the combined beam to the target.

The beam splitter 211 serves to distribute at least a portion of the combined beam. The beam splitter may adjust at least a portion of an output beam output from the laser device to be transmitted to the photo detector 213 in order to evaluate the coherence beam coupling state and adjust the phase modulator.

In order to identify the intensity of the output beam output from the laser device, the photodetector 213 may detect an optical signal related to the intensity of the beam and convert the optical signal into an electrical signal. According to an embodiment of the present disclosure, the photodetector 213 may detect an optical signal transmitted through the beam splitter and convert it into an electrical signal. Thereafter, the photodetector 213 may transmit the generated electrical signal to the phase controller 215 .

The phase controller 215 determines a phase value for coherent beam coupling by using information about beam intensity based on an electrical signal input to the photodetector. The phase controller 215 determines a phase value to be applied to the plurality of beams corresponding to the plurality of channels based on the perturbation signal to be applied to the plurality of signal beams corresponding to the plurality of channels and the input signal from the photodetector. In this case, the phase controller 215 may determine a phase value to be applied to the plurality of beams from the perturbation signal and the digital signal by performing the SPGD algorithm operation. According to an embodiment of the present disclosure, the phase controller 215 uses the SPGD algorithm to apply a perturbation signal to each of a plurality of signal beams corresponding to a plurality of channels, and then identifies the changing intensity of the laser beam, The phase value may be determined such that the intensity of the laser beam is maximized. The phase controller 215 may generate a phase control signal for controlling the phase modulator based on the phase value determined through the SPGD operation, and transmit the phase control signal to the phase modulator.

3 shows a configuration 300 of a phase controller in a coherent beam combining laser system that controls a phase based on a conventional SPGD algorithm. FIG. 3 illustrates the configuration of the phase controller 215 of the laser device of FIG. 2 .

Referring to FIG. 3 , the configuration 300 of the phase controller includes an ADC 301 , first perturbation generators to third perturbation generators 305-1 to 305-3, and first SPGD calculators to third SPGD calculators 307- 1 to 307-3), and first DACs to third DACs 309-1 to 309-3. 3 illustrates a case in which the phase controller includes three perturbation generators, SPGD operators, and DACs, respectively, the number of each of the perturbation generators, SPGD operators, and DACs may be changed according to the design of the phase controller. have.

The ADC 301 performs a function of converting an analog signal into a digital signal. The ADC 301 may convert an analog input signal regarding beam intensity into a digital signal. According to an embodiment of the present disclosure, the ADC 301 may convert an electrical signal input from the photodetector into a digital signal in order to identify coherent beam coupling.

The first to third perturbation generators 305-1 to 305-3 perform a function of generating a perturbation signal. The first to third perturbation generators 305 - 1 to 305 - 3 may generate a perturbation signal for generating a phase perturbation of the signal beam. According to an embodiment of the present disclosure, the first perturbation generator to the third perturbation generator 305-1 to 305-3 may generate a random perturbation signal to be applied to a plurality of signal beams corresponding to a plurality of channels. . According to an embodiment of the present disclosure, the first to third perturbation generators 305 - 1 to 305 - 3 may include random number generators (RNGs).

The first to third SPGD operators 307-1 to 307-3 perform a function of determining a phase to be applied to beams corresponding to a plurality of channels. The first to third SPGD calculators 307-1 to 307-3 use the perturbation signal transmitted from the first perturbation generator to the third perturbation generator and the digital signal regarding the intensity of the beam transmitted from the ADC to perform SPGD. Perform algorithmic operation. According to an embodiment of the present disclosure, the first SPGD operator to the third SPGD operator 307-1 to 307-3 use the SPGD algorithm to determine a phase value such that the intensity of the laser beam is maximized, and the determined phase value may generate a phase control signal for controlling the phase of the phase modulator. The first to third SPGD operators 307 - 1 to 307 - 3 may transmit the generated phase control signals to the first to third DACs 309 - 1 to 309 - 3 , respectively.

The first to third DACs 309-1 to 309-3 perform a function of converting an input digital signal into an analog signal. According to an embodiment of the present disclosure, the first DACs to the third DACs 309-1 to 309-3 are digital forms received from the first SPGD operators 307-1 to the third SPGD operators 307-1 to 307-3, respectively. converts the phase control signals of , into analog phase control signals. Thereafter, the first to third DACs 309 - 1 to 309 - 3 may transmit the generated analog phase control signal to each of the phase modulators. According to an embodiment of the present disclosure, the first to third DACs 309-1 to 309-3 transmit the generated phase control signals to the first to third phase modulators 205-1 of FIG. 2, respectively. to 205-3) can be delivered.

The phase control method using the SPGD algorithm has a small amount of calculation, so it is easy to design a phase controller and it is possible to perform phase control in real time. However, the phase control method using the SPGD algorithm is vulnerable to the occurrence of laser fluctuations because, when the intensity of the laser beam decreases due to the laser fluctuations in the phase lock state, it is recognized as the beam coupling released state. That is, the phase controller using the SPGD algorithm recognizes that when the intensity of the beam is momentarily reduced due to laser fluctuations occurring in the beam coupling state, it is recognized as a phase decoupling phenomenon, and the operation of finding the phase lock state based on the SPGD algorithm operation is repeated. According to the conventional phase control method using the SPGD algorithm, the beam combining efficiency decreases as the operation of finding the phase to be the beam combining is repeated in order to find the phase lock state.

4 illustrates a configuration of a phase controller 400 in a coherent beam combining laser system for controlling a phase based on an SPGD algorithm according to various embodiments of the present disclosure. FIG. 3 illustrates the configuration of a phase controller of the laser device of FIG. 2 .

Referring to FIG. 4 , the configuration of the phase controller 400 includes an ADC 401 , a moving average filter 403 , first perturbation generators to third perturbation generators 405-1 to 405-3 , and first SPGD calculators to It may include third SPGD operators 407-1 to 407-3 and first DACs to third DACs 409-1 to 409-3.

4 is related to a computational simulation method, a field programmable gate array (FPGA) board, and a three-channel laser system, exemplifying a case in which the phase controller includes three perturbation generators, SPGD operators, and DACs each, but the perturbation generator The number of each of the s, SPGD operators, and DACs may be changed according to the design of the phase controller.

The ADC 401 of FIG. 4 , the first perturbation generators to the third perturbation generators 405-1 to 405-3, the first SPGD operators to the third SPGD operators 407-1 to 407-3, and the first DACs to The third DACs 409-1 to 409-2 are the ADC 301 corresponding to the configuration in FIG. 3, the first perturbation generators to the third perturbation generators 305-1 to 305-3, and the first SPGD calculator. to the third SPGD operators 307-1 to 307-3 and the first DACs to the third DACs 309-1 to 309-2 may perform the same functions.

The ADC 401 converts an analog input signal into a digital signal. According to an embodiment of the present disclosure, the ADC 401 may convert an analog electrical signal regarding beam intensity input from the photodetector into a digital signal.

The moving average filter 403 performs a filtering function by continuously calculating the average of a plurality of consecutive data values. The moving average value indicates a real-time average value for a set number of input values. The moving average filter may perform filtering on noise and the like using the moving average value. The moving average filter may have an algorithm for accumulating input values and outputting an average value related to the sum at each sampling time. According to an embodiment of the present disclosure, the output signal of the ADC 401 may be input to a plurality of channels after the moving average filter is applied. Since the moving average filter is applied before the ADC output signal is input to a plurality of channels, the moving average filter 403 can be used even when the number of channels is increased.

The moving average filter may filter the digital signal input from the ADC 401 . According to an embodiment of the present disclosure, the moving average filter may include at least one of a simple moving average filter, a weighted moving average filter, a geometric moving average filter, and an exponential moving average filter.

The first to third perturbation generators 405 - 1 to 405 - 3 may generate a perturbation signal for generating a phase perturbation of the signal beam. The first to third perturbation generators 405 - 1 to 405 - 3 may randomly generate perturbation signals to be applied to a plurality of signal beams corresponding to a plurality of channels. According to an embodiment of the present disclosure, the first perturbation generators to the third perturbation generators 405-1 to 405-3 convert the generated perturbation signals, respectively, to the first SPGD operators to the third SPGD operators 407-1 to 407- 3) can be transferred.

The first to third SPGD operators 407-1 to 407-3 determine phases to be applied to beams corresponding to a plurality of channels. The first to third SPGD calculators 407-1 to 407-3 use the perturbation signal transmitted from the first perturbation generator to the third perturbation generator and the digital signal regarding the intensity of the beam to which the moving average filter is applied. SPGD algorithm operation can be performed. According to an embodiment of the present disclosure, the first SPGD calculator to the third SPGD calculator 407-1 to 407-3 uses the SPGD algorithm to determine the phase value so that the intensity of the laser beam is maximized, and the determined phase value It is possible to generate a digital form of a phase control signal from The first to third SPGD operators 407 - 1 to 407 - 3 may transmit the generated phase control signals to the first to third DACs 409 - 1 to 409 - 3 , respectively.

The first to third DACs 409-1 to 409-3 convert the digital phase control signals received from each of the first to third SPGD operators 407-1 to 407-3 in analog form. It can be converted into control signals and passed to each of the phase modulators. According to an embodiment of the present disclosure, the first to third DACs 409-1 to 409-3 transmit the generated phase control signals to the first to third phase modulators 205-1 of FIG. 2, respectively. to 205-3) can be delivered.

The phase control method using the SPGD algorithm according to the present disclosure applies a moving average filter to the input signal regarding the intensity of the laser beam input to the phase controller, thereby preventing the decoherence phenomenon caused by the instantaneous decrease in laser beam intensity due to laser fluctuations. can be prevented In the phase control method using the SPGD algorithm according to the present disclosure, when the intensity of a laser beam is reduced due to laser fluctuations, the beam coupling state is not identified as the released state based on the moving average filter. Accordingly, the beam combining efficiency can be improved.

5 shows a signal graph 500 regarding the intensity of a laser beam in a conventional coherent beam coupling laser system and a coherent beam coupling laser system according to various embodiments of the present disclosure. 5 illustrates a conventional coherent beam-combining laser system 501 and a coherent beam-combining laser system 503 to which a moving average filter is applied.

Referring to FIG. 5 , the intensity of the beam in the coherent beam combining laser system 503 to which the moving average filter is applied has a more stable value than the intensity of the beam output by the laser device in the conventional coherent beam combining laser system 501 . case is shown. When beam combining is performed using an oscillated laser beam, the intensity of the combined beam may be momentarily reduced due to laser fluctuations.

When the intensity of the beam is momentarily reduced, according to the conventional coherent beam-combining laser system 501, the phase controller identifies the beam state as the beam-coupled uncoupled state, and determines the phase value of the beam and modulates the phase through SPGD algorithm operation do it again As the SPGD algorithm is repeatedly performed, the change in output with respect to the intensity of the beam may have a large unstable value.

When the beam intensity is momentarily reduced, according to the coherent beam combining laser system 503 to which the moving average filter is applied, the phase controller identifies that the beam combining state is maintained using the moving average filter, and SPGD for phase locking Algorithm operation is not performed. Accordingly, the output with respect to the intensity of the beam may have a stable value with little change.

6 illustrates a flowchart 600 of a method of operating a phase controller in a coherent beam combining laser system for controlling a phase based on an SPGD algorithm according to various embodiments of the present disclosure. 6 illustrates a method of operation of the phase controller 400 of FIG. 4 .

Referring to FIG. 6 , in step 601 , the phase controller 400 converts an analog input signal regarding beam intensity into a digital signal. According to an embodiment of the present disclosure, the phase controller 400 converts an input signal related to the intensity of a beam input from the photodetector into a digital signal using the ADC.

In step 603, the phase controller 400 applies a moving average filter to the digital signal relating to the intensity of the beam. The phase controller 400 applies a moving average filter to the digital signal output by the ADC. According to an embodiment of the present disclosure, the moving average filter may be configured to filter a signal based on an average value of continuously input beam intensity values in a signal related to beam intensity. According to an embodiment of the present disclosure, the moving average filter may include at least one of a simple moving average filter, a weighted moving average filter, a geometric moving average filter, and an exponential moving average filter. According to an embodiment of the present disclosure, a signal regarding the intensity of a beam to which the moving average filter is applied may be transmitted to the SPGD operator.

In step 605, the phase controller 400 generates a perturbation signal applied to a beam corresponding to one of the plurality of channels. According to an embodiment of the present disclosure, the phase controller 400 may generate a random perturbation signal to be applied to a plurality of signal beams corresponding to a plurality of channels by using a perturbation generator. According to an embodiment of the present disclosure, the phase controller 400 may use a random number generator as a perturbation generator. According to an embodiment of the present disclosure, the perturbation signal generated by the perturbation generator may be transmitted to the SPGD operator.

In operation 607, the phase controller 400 determines a phase value for modulating a phase of a beam corresponding to one of a plurality of channels, based on the beam intensity signal filtered by the moving average filter and the perturbation signal. The phase controller 400 may determine a phase value for modulating the phase of the beam using the SPGD operator. According to an embodiment of the present disclosure, the phase controller 400 may perform the SPGD algorithm operation using the perturbation signal received from the perturbation generator and the signal regarding the intensity of the beam to which the moving average filter is applied. The phase controller may use the SPGD algorithm to determine a phase value at which the intensity of the laser beam is maximum and generate a digital phase control signal from the determined phase value. According to an embodiment of the present disclosure, the SPGD operator may transmit each of the generated phase control signals to the DAC.

According to an embodiment of the present disclosure, when the average value of the intensity values of the beam is less than or equal to the threshold value, the phase controller 400 identifies the state of the beam output from the laser device as the uncoupling state, and When the average value is greater than the threshold value, the state of the beam output by the laser device may be identified as the beam coupling state. The phase controller 400 identifies a case in which the average value regarding the intensity of the beam determined based on the moving average filter is less than a preset threshold value as the beam coupling released state, and determines the case where the average value is greater than the preset threshold value. It can be identified by the state in which the bond is maintained. Accordingly, the phase controller 400 may not identify the instantaneous decrease in intensity of the beam as a phase out of phase, and may not perform the SPGD algorithm operation for phase locking.

In step 609, the phase controller 400 converts the phase control signal related to the phase value into an analog signal. The phase controller 400 may convert the digital phase control signal into analog phase control signals using the DAC. The phase controller 400 may output an analog phase control signal to the phase modulator.

Methods according to the embodiments described in the claims or specifications of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium are configured to be executable by one or more processors in an electronic device (device). One or more programs include instructions for causing an electronic device to execute methods according to embodiments described in a claim or specification of the present disclosure.

Such programs (software modules, software) include random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable ROM (electrically erasable programmable read only memory, EEPROM), magnetic disc storage device, compact disc-ROM (CD-ROM), digital versatile discs (DVDs), or other It may be stored in an optical storage device or a magnetic cassette. Alternatively, it may be stored in a memory composed of a combination of some or all thereof. In addition, each configuration memory may be included in plurality.

In addition, the program is transmitted through a communication network composed of a communication network such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), or a storage area network (SAN), or a combination thereof. It may be stored on an attachable storage device that can be accessed. Such a storage device may be connected to a device implementing an embodiment of the present disclosure through an external port. In addition, a separate storage device on the communication network may be connected to the device implementing the embodiment of the present disclosure.

In the specific embodiments of the present disclosure described above, elements included in the disclosure are expressed in the singular or plural according to the specific embodiments presented. However, the singular or plural expression is appropriately selected for the context presented for convenience of description, and the present disclosure is not limited to the singular or plural component, and even if the component is expressed in plural, it is composed of the singular or singular. Even an expressed component may be composed of a plurality of components.

Meanwhile, although specific embodiments have been described in the detailed description of the present disclosure, various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments and should be defined by the claims described below as well as the claims and equivalents.

Claims (8)

A phase controller for controlling phase modulation of a signal beam using a plurality of channels in a coherent beam combining laser system for controlling a phase based on a stochastic parallel gradient descent (SPGD) algorithm, the phase controller comprising:
ADC (analog to digital converter) for converting an analog input signal related to beam intensity into a digital signal;
a moving average filter for filtering the digital signal regarding the intensity of the beam;
a perturbation generator for generating a perturbation signal applied to a beam corresponding to one of the plurality of channels;
an SPGD calculator configured to determine a phase value for modulating a phase of a beam corresponding to one of the plurality of channels based on the beam intensity signal filtered by the moving average filter and the perturbation signal; and
and a digital to analog converter (DAC) for converting a phase control signal related to the phase value into an analog signal.
The method according to claim 1,
and the moving average filter is configured to filter the signal based on an average value of continuously input beam intensity values from the beam intensity signal.
The method according to claim 1,
The moving average filter may include at least one of a simple moving average filter, a weighted moving average filter, a geometric moving average filter, and an exponential moving average filter.
In a coherent beam combining laser system that controls a phase based on a stochastic parallel gradient descent (SPGD) algorithm, in a laser device,
an oscillator for generating a signal beam;
a beam splitter for distributing the signal beam to correspond to a plurality of channels;
a phase modulator for modulating a phase of the distributed signal beam;
a photodetector that converts an optical signal related to the intensity of a beam output by the laser device into an electrical signal;
an analog to digital converter (ADC) that converts an analog input signal related to the intensity of the beam received from the photodetector into a digital signal, a moving average filter that filters the digital signal related to the intensity of the beam; a perturbation generator for generating a perturbation signal applied to a beam corresponding to one of the plurality of channels; A phase controller comprising an SPGD operator for determining a phase value for modulating the phase of the beam, and a digital to analog converter (DAC) for converting a phase control signal related to the phase value into an analog signal,
The phase modulator modulates a laser phase to correspond to the phase value based on the phase control signal transmitted from the phase controller.
5. The method of claim 4,
The moving average filter is configured to filter a signal based on an average value of continuously input beam intensity values in the signal related to the intensity of the beam.
6. The method of claim 5,
The phase controller is
When the average value of the intensity values of the beam is less than or equal to a threshold value determined based on the moving average filter, the state of the beam output by the laser device is identified as a beam coupling release state,
When the average value of the intensity values of the beam is greater than the threshold value, the laser device identifies the state of the beam output from the laser device as the beam coupling state.
A method of operating a phase controller for controlling phase modulation of a signal beam using a plurality of channels in a coherent beam combining laser system for controlling a phase based on a stochastic parallel gradient descent (SPGD) algorithm, the method comprising:
converting an analog input signal regarding beam intensity into a digital signal;
applying a moving average filter to the digital signal regarding the intensity of the beam;
generating a perturbation signal applied to a beam corresponding to one of the plurality of channels;
determining a phase value for modulating a phase of a beam corresponding to one of the plurality of channels based on the beam intensity signal filtered by the moving average filter and the perturbation signal; and
and converting a phase control signal related to the phase value into an analog signal.
8. The method of claim 7,
identifying a state of a beam output by the laser device as a beam coupling release state when the average value of the intensity values of the beams continuously input in the signal related to the intensity of the beam is less than or equal to a threshold value; and
and when the average value of the intensity values of the beam is greater than the threshold value, identifying the state of the beam output from the laser device as a beam coupling state.

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