KR101010818B1 - Oscillation wave linear sweep control device and method of swept laser - Google Patents

Abstract

Disclosed are an oscillation wave linear sweeping control device and a filtering method of a swept laser capable of linearly sweeping an oscillation wave. Oscillation frequency linear sweep control method of the swept laser according to an embodiment of the present invention comprises the steps of generating a linear sawtooth waveform information that changes linearly; Generating a sawtooth waveform signal corresponding to the linear sawtooth waveform information; Generating light and changing and outputting the oscillation wave number of the light according to the sawtooth waveform signal; Generating an electrical signal based on the light output in the outputting step; Generating an external clock based on the electrical signal; Generating an internal clock representing a predetermined time; Sampling the sawtooth waveform signal with the external clock to generate first information; Sampling the sawtooth waveform signal with the internal clock to generate second information; And generating sawtooth waveform information modified based on the difference between the first information and the second information.

DAQ boards, optocouplers, waveforms, sawtooth waveforms, clocks.

Description

CONTROL APPARATUS AND METHOD FOR WAVENUMBER LINEAR SWEEPING OF SWEPT LASER}

The present invention relates to an oscillation wave linear sweeping control device and method of a swept laser, and more particularly, to a control method of a variable wavelength filter. An apparatus and method for oscillating wave linear sweeping control of a swept laser for linearly controlling a change in oscillation wave over time by compensating for an appropriate response characteristic.

The fast broadband tunable characteristic is an important characteristic of a swept source laser, and the performance of the fast broadband tunable characteristic depends on the tunable filter.

The conventional tunable filter controls the oscillation wave of the swept source laser by transmitting a signal having an appropriate magnitude and frequency to the piezoelectric element. In this case, the displacement of the piezoelectric element corresponding to the shape and size of the signal does not change linearly in proportion to the frequency and instantaneous values of the applied signal, but is nonlinear according to the internal capacitance of the piezoelectric element and the impedance characteristic according to the frequency. It is a real response. Therefore, the piezoelectric element has a problem in that variations occur in reproducibility and repeatability with respect to the same frequency.

Accordingly, there is a need for an oscillation wave linear sweeping control device and a filtering method of a swept laser in which the oscillation wave of light generated by the swept laser can be changed linearly in proportion to the frequency and instantaneous value of the signal applied to the tunable filter.

The present invention provides an apparatus and method for oscillating wave linear sweep control of a swept laser which can linearly control a change in light over time by modifying information applied to a laser generating device in real time.

An oscillation wave linear sweeping control apparatus of a swept laser according to an embodiment of the present invention includes a control unit for generating and transmitting linear sawtooth waveform information that changes linearly; An arbitrary waveform generator for generating a sawtooth waveform signal in response to the linear sawtooth waveform information; A laser generator for generating light and changing and outputting the oscillation wave number of the light according to the sawtooth waveform signal; A signal generator configured to generate an electrical signal based on the light output from the laser generator; An external clock generator configured to generate an external clock based on the electrical signal; And a board unit generating an internal clock, sampling the sawtooth waveform signal with the external clock to generate first information, and generating a second information by sampling the sawtooth waveform signal into the internal clock. May generate the modified sawtooth waveform information based on the difference between the first information and the second information and transmit the modified sawtooth waveform information to the arbitrary waveform generator.

Oscillation frequency linear sweep control method of the swept laser according to an embodiment of the present invention comprises the steps of generating a linear sawtooth waveform information that changes linearly; Generating a sawtooth waveform signal corresponding to the linear sawtooth waveform information; Generating light and changing and outputting the oscillation wave number of the light according to the sawtooth waveform signal; Generating an electrical signal based on the light output in the outputting step; Generating an external clock based on the electrical signal; Generating an internal clock representing a predetermined time; Sampling the sawtooth waveform signal with the external clock to generate first information; Sampling the sawtooth waveform signal with the internal clock to generate second information; And generating sawtooth waveform information modified based on the difference between the first information and the second information.

According to the present invention, it is possible to linearly control the change of light over time by correcting the information applied to the laser generating device in real time.

Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

1 is an example showing an overview of an oscillation wave linear sweeping control device of a swept laser according to an embodiment of the present invention.

The oscillation wave linear sweeping control apparatus of the swept laser according to the embodiment of the present invention, as shown in Figure 1, the control unit 110, the arbitrary waveform generator 120, the laser generator 130, the signal generator 140 ), An external clock generator 150, a trigger signal generator 160, and a board unit 170.

The controller 110 may generate linear sawtooth waveform information that changes linearly and transmit the linear sawtooth waveform information to the arbitrary waveform generator 120. In addition, the controller 110 may generate the modified sawtooth waveform information based on the information provided from the board unit 170 and transmit the modified sawtooth waveform information to the arbitrary waveform generator 120.

The arbitrary waveform generator 120 may generate a sawtooth waveform signal in response to the sawtooth waveform information transmitted from the controller 110. In this case, the sawtooth waveform information may include the linear sawtooth waveform information and the modified sawtooth waveform information.

The arbitrary waveform generator 120 generates a sawtooth waveform signal according to the random value generator 121 and a random value generator 121 for generating a random value to form a waveform according to the sawtooth waveform information, and generates a waveform according to the laser generator 130 and the board. The waveform generator 122 may be transmitted to the unit 170.

The laser generator 130 may generate light and change the oscillation wave number of the light according to the sawtooth waveform signal generated by the arbitrary waveform generator 120 to output the light.

In this case, the laser generator 130 may include the gain medium 131, the isolators 132 and 134, the variable wavelength filter 133, the polarization controller 135, the first optocoupler 136, the second optocoupler 137, and the It may consist of a fiber delay line 138 connecting the configuration.

In this case, when the gain medium 131 generates light and emits it from side to side, the isolators 132 and 134 fix the traveling direction of the light in one direction, and the tunable filter 133 oscillates the light in response to the sawtooth waveform signal. You can change the frequency. In this case, a SOA (Semiconductor Optical Amplifier) may be used as the gain medium 131, and the polarization controller 135 may control the traveling speed of the light.

In this case, the wavelength variable filter 133 may periodically change the oscillation wave number of the light passing through the variable wavelength filter 133 according to the sawtooth waveform signal applied from the waveform generator 122 to sweep.

The first optocoupler 136 is a 50:50 optocoupler, and the optical power of the light may be divided into 50:50 and transmitted to another configuration of the laser generator and the second optocoupler 137. For example, in FIG. 1, the first optocoupler 136 is installed between the gain medium 131 and the isolator 132, and the isolators 132 and 134 fix the traveling direction of the light clockwise. The optical power of the light may be divided into 50:50 and one may be transmitted to the isolator 132 and the other may be transmitted to the second optical coupler 137.

The second optocoupler 137 is a 90:10 optocoupler that divides the optical power of the light transmitted from the first optocoupler 136 into 90:10 and transmits the optical power corresponding to 10 to the signal generator 140. have.

The signal generator 140 may generate an electrical signal based on the light output from the laser generator 130.

In this case, the signal generator 140 may include an optical circulator 141, a shaping optical filter 142, and a balanced receiver 143.

The shaping optical filter 142 may use a Michelson interferometer as shown in FIG. 1. At this time, the Michelson interferometer may satisfy the following equation (1).

Δv = c / 2Δd

Δk = π / △ d

In this case, Δv is a frequency interval and c may be an optical speed. Δd may be a distance between C1 and L1 or a distance between C2 and L2, and Δk may be a frequency interval.

In this case, when the light output from the laser generator 130 passes through the optical circulator 141 and enters the shaping optical filter 142, the shaping optical filter 142 has an oscillation frequency of the light shaping the optical filter 142. Whenever the signal coincides with the pass frequency band of, a sinusoidal electrical signal may be generated and transmitted.

The external clock generator 150 may generate an external clock based on the electrical signal generated by the signal generator 140.

In this case, the external clock generator 150 may include a band pass filter 151 and a clock generator 152. In this case, the clock generator 152 may include an amplifier and a comparator.

In this case, when the external clock generator 150 filters the electrical signal by the band pass filter 151, the external clock generator 152 amplifies the filtered electrical signal through the clock generator 152 and passes the comparator to change the external signal in the same period as the sine wave. You can generate a clock.

The trigger signal generator 160 may generate a trigger signal for controlling the sampling timing of the board unit 170.

The board unit 170 may generate an internal clock, sample the sawtooth waveform signal with the external clock to generate first information, and sample the sawtooth waveform signal with the internal clock to generate second information. have. In this case, a data acquisition (DAQ) board may be used as the board unit 170.

In this case, as shown in FIG. 2, the board unit 170 includes a trigger signal receiver 210, a sawtooth waveform signal receiver 220, a transceiver 230, an internal clock generator 240, and a sampling unit 250. It can be configured as.

The trigger signal receiver 210 may receive the trigger signal from the trigger signal generator 170. In addition, the trigger signal receiver 210 may be channel B when the board unit 170 is a DAQ board.

The sawtooth waveform signal receiver 220 may receive the sawtooth waveform signal periodically from the waveform generator 122. In addition, the sawtooth waveform signal receiver 220 may be channel A when the board unit 170 is a DAQ board.

The transceiver 230 receives the external clock from the external clock generator 150, transmits the external clock to the sampling unit 250, and receives the first information and the second information from the sampling unit 250. And transmit to 110.

In this case, the external clock received by the transceiver 230 corresponds to the sinusoidal wave signal 310 generated by the signal generator 140 as illustrated in FIG. 3 and the plurality of rising edges 320. It may include. In this case, the interval of the rising edge 320 may be changed non-linearly with time as shown in FIG.

The internal clock generator 240 may generate an internal clock representing a predetermined time.

The sampling unit 250 checks the trigger signal received by the trigger signal receiving unit 210, and if the trigger signal exceeds a preset trigger level, sample the sawtooth waveform signal to have a waveform as shown in FIG. 4. The first information 410 and the second information 420 may be generated.

In detail, the sampling unit 250 may generate the first information 410 by sampling the sawtooth waveform signal at the rising edge or the falling edge of the external clock.

In addition, the sampling unit 250 may generate the second information 420 by sampling the sawtooth waveform signal at predetermined time intervals according to the internal clock.

In this case, as shown in FIG. 4, when time elapses, the first information 410 may change nonlinearly according to the change of the external clock, but the second information 420 does not change since the internal clock does not change. Can change linearly.

The controller 110 calculates the difference value 430 by subtracting the value of the second information 420 from the value of the first information 410, and the sawtooth waveform linearly changing a predetermined ratio of the difference value 430. By generating the modified sawtooth waveform information in addition to the information, by changing the signal transmitted to the wavelength variable filter 133 according to the change in the light generated by the laser generator 130 over time to change the light over time Can be controlled linearly.

For example, when the linear sawtooth waveform is used without change, the waveform 510 changes nonlinearly with time, but the waveform 520 using the sawtooth waveform information modified by the controller 110 corrects an element that changes with time. Can be changed linearly.

In addition, the controller 110 checks whether the difference value 430 is closer to zero than the predetermined value, stops the operation when the difference value 430 is closer to zero than the predetermined value, and the difference value is equal to zero than the predetermined value. If not, the arbitrary waveform generator 120 corrects the light of the laser generator 130 using the modified sawtooth waveform information, and the corrected light is generated by the signal generator 140 and the external clock generator 150. The modified external clock may be generated through the process, and the board unit 170 may repeat the process of generating new first information 410 and second information 420 according to the modified external clock. In this case, the predetermined value is a value that is limited by the maximum precision that can be expressed in an element or apparatus used in the oscillation wave linear sweeping control apparatus of the swept laser according to an embodiment of the present invention. Can be a value.

In addition, the oscillation wave linear sweeping control apparatus of the swept laser according to an embodiment of the present invention can improve the speed of an image frame by performing the same operation on the sawtooth waveforms of the remaining half periods (falling edge).

6 is a flowchart illustrating a method of controlling oscillation wave linear sweeping of a swept laser according to an embodiment of the present invention.

In operation S610, the laser generator 130 may sweep the oscillation wave number of the light with a linear sawtooth waveform. In detail, the laser generator 130 generates light, and the sawtooth waveform generated by the arbitrary waveform generator 120 corresponds to the linear sawtooth waveform information that linearly changes the oscillation wave number of the light generated by the controller 110. The output can be changed to sweep according to the signal.

In operation S620, the signal generator 140 may generate an electrical signal based on the light output in operation S610. In detail, the signal generator 140 may generate the sinusoidal electric signal by incident the light output in operation S610 into the shaping optical filter 142.

In operation S630, the external clock generator 150 may generate an external clock based on the electrical signal. Specifically, when the external clock generator 150 filters the electric signal by the band pass filter 151, the external clock generator 150 amplifies the filtered electric signal by the clock generator 152 and passes the comparator to change the signal in the same period as the sine wave. A tunnel clock can be generated.

In operation S640, the board unit 170 may generate first information by sampling the sawtooth waveform signal generated by the arbitrary waveform generator 120 using the external clock generated in operation S630.

In operation S650, the board unit 170 may generate the second information by sampling the sawtooth waveform signal as an internal clock representing a predetermined time generated by the internal clock generator 240 of the board unit 170.

In operation S660, the controller 110 may generate the sawtooth waveform information modified based on the difference between the first information generated in operation S640 and the second information generated in operation S650. In this case, the controller 110 calculates a difference value by subtracting the value of the second information from the value of the first information, and corrects the sawtooth waveform information by adding a predetermined ratio of the difference value to the linearly changing sawtooth waveform information. Can be generated.

In operation S670, the laser generator 130 may sweep the oscillation wave number of the light with the modified sawtooth waveform. Specifically, in response to the modified linear sawtooth waveform information, the oscillation wave number of the light may be changed and output according to the sawtooth waveform signal generated by the arbitrary waveform generator 120.

In step S680, the controller 110 checks whether the difference value is closer to zero than the predetermined value, and if the difference value is not closer to zero than the predetermined value, repeats the steps S620 to S670. can do. In this case, the predetermined value is a value that is limited by the maximum precision that can be expressed in an element or apparatus used in the oscillation wave linear sweeping control apparatus of the swept laser according to an embodiment of the present invention. Can be a value.

As described above, the oscillation wave linear sweeping control apparatus and generation method of the swept laser according to the present invention are a value obtained by sampling a sawtooth waveform signal with an external clock generated according to the optical state of the laser generator, and the sawtooth waveform signal. By generating the modified sawtooth waveform information based on the difference of the value sampled by the internal clock, and modifying the optical oscillation wave number using the sawtooth waveform information it is possible to linearly control the change of light over time.

As described above, the present invention has been described by specific embodiments such as specific components and the like. For those skilled in the art, various modifications and variations are possible from these descriptions.

Therefore, the spirit of the present invention should not be construed as being limited to the described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, are included in the scope of the present invention.

1 is an example showing an overview of an oscillation wave linear sweeping control device of a swept laser according to an embodiment of the present invention.

Figure 2 is an example showing an overview of the board unit according to an embodiment of the present invention.

3 is an example of a sinusoidal signal generated by a signal generator and an external clock generated by an external clock generator according to an embodiment of the present invention.

4 is an example of signals sampled from a board unit according to an exemplary embodiment of the present invention.

5 is an example of the waveform of light according to the linear sawtooth waveform information and the modified sawtooth waveform information according to an embodiment of the present invention.

FIG. 6 is a flowchart illustrating an oscillation wave linear sweeping control method of a swept laser according to an embodiment of the present invention.

Claims (15)

A controller for generating and transmitting linear sawtooth waveform information that changes linearly; An arbitrary waveform generator for generating a sawtooth waveform signal in response to the linear sawtooth waveform information; A laser generator for generating light and changing and outputting the oscillation wave number of the light according to the sawtooth waveform signal; A signal generator configured to generate an electrical signal based on the light output from the laser generator; An external clock generator configured to generate an external clock based on the electrical signal; And A board unit generating an internal clock, sampling the sawtooth waveform signal with the external clock to generate first information, and generating a second information by sampling the sawtooth waveform signal into the internal clock. Including, And the control unit generates the modified sawtooth waveform information based on the difference between the first information and the second information and transmits the modified sawtooth waveform information to the arbitrary waveform generator. The method of claim 1, The laser generation unit, Gain medium for generating light; At least one isolator for controlling a traveling direction of the light; A variable wavelength filter for changing the oscillation wave number of the light in response to the sawtooth waveform signal; And An optical coupler that divides the optical power of the light and transmits the optical power to the signal generator Oscillation frequency linear sweep control device of a swept laser, characterized in that it comprises a. The method of claim 2, The optocoupler, A first optical coupler for dividing the optical power of the light by 50:50 and transmitting the optical power to the second optical coupler and the other components of the laser generator; And A second optical coupler that splits the optical power of the light transmitted from the first optical coupler into 90:10 and transmits the optical power of 10 to the signal generator Oscillation frequency linear sweep control device of a swept laser, characterized in that it comprises a. The method of claim 1, And the signal changer generates a sinusoidal electric signal by injecting the light generated by the laser generator into a shaping optical filter. The method of claim 1, And a trigger signal generator configured to generate a trigger signal for controlling the sampling timing of the board unit. The method of claim 5, The board unit, A trigger signal receiver configured to receive the trigger signal from the trigger signal generator; A sawtooth waveform signal receiving unit for receiving the sawtooth waveform signal from the arbitrary waveform generator; An internal clock generator configured to generate an internal clock representing a predetermined time; When the trigger signal exceeds a preset trigger level, the sawtooth waveform signal is generated at the rising edge or the falling edge of the external clock to generate first information, and the sawtooth waveform signal is generated at a predetermined time interval according to the internal clock. A sampling unit for sampling and generating second information; And A transceiver configured to receive the external clock from the external clock generator and to transmit the first information and the second information to the controller; Oscillation frequency linear sweep control device of a swept laser, characterized in that it comprises a. The method of claim 1, The control unit calculates a difference value by subtracting the value of the second information from the value of the first information, and generates a modified sawtooth waveform information by adding a predetermined ratio of the difference value to the linearly changing sawtooth waveform information. An oscillation frequency linear sweep control device of a swept laser. The method of claim 1, And the arbitrary waveform generator generates a sawtooth waveform signal in response to the corrected sawtooth waveform information when the controller transmits the modified sawtooth waveform information to the oscillation frequency linear sweeping control device of the swept laser. Generating linear sawtooth waveform information that varies linearly; Generating a sawtooth waveform signal corresponding to the linear sawtooth waveform information; Generating light and changing and outputting the oscillation wave number of the light according to the sawtooth waveform signal; Generating an electrical signal based on the light output in the outputting step; Generating an external clock based on the electrical signal; Generating an internal clock representing a predetermined time; Sampling the sawtooth waveform signal with the external clock to generate first information; Sampling the sawtooth waveform signal with the internal clock to generate second information; And, Generating modified sawtooth waveform information based on the difference between the first information and the second information. Oscillation frequency linear sweeping control method of a swept laser, characterized in that it comprises a. 10. The method of claim 9, The generating of the electric signal may include generating the sinusoidal electric signal by injecting the light output from the outputting into a shaping optical filter to generate a sinusoidal electric wave. 10. The method of claim 9, The generating of the first information may include generating a first information by sampling the sawtooth waveform signal at a rising edge or a falling edge of the external clock when a trigger signal exceeds a preset trigger level. Oscillation frequency linear sweep control method. 10. The method of claim 9, The generating of the second information may include generating the second information by sampling the sawtooth waveform signal at predetermined time intervals according to the internal clock. 10. The method of claim 9, Generating the modified sawtooth waveform information, Calculating a difference value by subtracting the value of the second information from the value of the first information; And Generating modified sawtooth waveform information by adding a predetermined ratio of the difference value to the linearly changing sawtooth waveform information Oscillation frequency linear sweeping control method of a swept laser, characterized in that it comprises a. The method of claim 13, And generating a sawtooth waveform signal in response to the corrected sawtooth waveform information. The method of claim 14, Checking whether the difference value is closer to 0 than a predetermined value More, The control unit repeats the step of outputting the light or generating a sawtooth waveform signal in response to the modified sawtooth waveform information when the difference value is not closer to 0 than a predetermined value. Oscillation frequency linear sweep control method.

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