CN112290365A - Laser, mode locking method and device - Google Patents
Laser, mode locking method and device Download PDFInfo
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- CN112290365A CN112290365A CN202011085624.XA CN202011085624A CN112290365A CN 112290365 A CN112290365 A CN 112290365A CN 202011085624 A CN202011085624 A CN 202011085624A CN 112290365 A CN112290365 A CN 112290365A
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- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1106—Mode locking
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/065—Mode locking; Mode suppression; Mode selection ; Self pulsating
- H01S5/0657—Mode locking, i.e. generation of pulses at a frequency corresponding to a roundtrip in the cavity
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Abstract
The application relates to a laser, a mode locking method and a mode locking device, which comprise the steps of obtaining a frequency value of pulse laser; the pulse laser is collected at an output port of the laser or a seed light source of the laser; sending a current adjusting signal according to the frequency value; the frequency value is greater than a standard frequency to send a first signal, the frequency value is less than the standard frequency to send a second signal, and the standard frequency is the frequency of the output pulse laser when mode locking is successful; adjusting the working current of the laser according to the current adjusting signal; wherein the operating current is reduced by a first step magnitude for the first signal and increased by a second step magnitude for the second signal; and judging the mode locking state, and if the mode locking state is successful, ending the mode locking program. This application has that the mode locking flow is simple, the fast effect of mode locking.
Description
Technical Field
The application relates to the technical field of laser, in particular to a laser, a mode locking method and a mode locking device.
Background
Ultrashort pulse laser has very narrow pulse width, ultrahigh peak power and ultrahigh repetition frequency, and is widely applied to the fields of medical treatment, scientific research, industry and the like. In order to obtain ultrashort pulse laser, mode locking operation needs to be performed on a laser, so that phase fixation is achieved among a plurality of longitudinal oscillation modes which have different oscillation frequencies and are not coherent in a laser resonant cavity, a regular ultrashort pulse sequence is obtained, and ultrashort pulse laser obtained by coherent superposition of the different longitudinal oscillation modes is output.
In the use, laser device can take place ageing, makes laser device operating current drift, leads to the mode locking state to lose the lock, in order to ensure that the stable ultrashort pulse laser of laser output, need carry out mode locking again to the laser, and at present, the mode locking scheme all adopts the laser intracavity to insert wave plate or manual polarization controller to adjust the mode locking state of fiber laser.
The mode locking scheme has no pertinence to the loss of lock caused by current drift, the adjusting process is complex, and the mode locking time is long again.
Disclosure of Invention
In order to simplify the mode locking process and improve the mode locking speed, the application provides a laser, a mode locking method and a mode locking device.
In a first aspect, the present application provides a mode locking method, which adopts the following technical scheme:
a method of mode locking, comprising:
acquiring a frequency value of the pulse laser; the pulse laser is collected at an output port of the laser or a seed light source of the laser;
sending a current adjusting signal according to the frequency value; the frequency value is greater than a standard frequency to send a first signal, the frequency value is less than the standard frequency to send a second signal, and the standard frequency is the frequency of the output pulse laser when mode locking is successful;
adjusting the working current of the laser according to the current adjusting signal; wherein the operating current is reduced by a first step magnitude for the first signal and increased by a second step magnitude for the second signal;
and judging the mode locking state, and if the mode locking state is successful, ending the mode locking program.
By adopting the technical scheme, different current adjusting signals are sent according to the relationship between the laser pulse frequency and the standard frequency, the adjustment of working current is realized, the problem of lock losing caused by current drift is solved, the mode locking process is simple, the mode locking speed is high, and the mode locking device can be applied to any laser.
Preferably, the determining the mode-locked state includes:
acquiring a frequency value of the pulse laser;
judging the mode locking state according to the frequency value; wherein:
the frequency value is within a first threshold value range and is within the first threshold value range continuously for multiple times, and the mode locking state is judged to be successful;
and if the frequency value is not in the first threshold range and is not in the first threshold range for a plurality of times continuously, judging that the mode locking state is mode locking failure.
Through adopting above-mentioned technical scheme, when carrying out mode locking state judgement, only when the laser instrument is in stable mode locking state, just carry out the mode locking state and detect for the mode locking is successful or the judgement that the mode locking failed, avoid appearing accidental error because of other steps in the judgement process, cause disconnected mode locking state erroneous judgement, effectively improve mode locking state result reliability, and the flow is simple, and judgement speed is fast to further improve the mode locking speed.
Preferably, the frequency value of the acquired pulsed laser includes:
converting the pulsed laser into a voltage pulse signal;
detecting the time interval between the rising edges of two adjacent voltage pulse signals;
and calculating the frequency value of the voltage pulse signal according to the time interval, and taking the frequency value of the voltage pulse signal as the frequency value of the pulse laser.
By adopting the technical scheme, the calculation speed of the voltage pulse signal frequency value is high, the accuracy and the reliability of the mode locking state judgment result are improved, and the mode locking state judgment speed is greatly improved, so that the mode locking speed is improved.
Preferably, before the obtaining the frequency value of the voltage pulse signal, the method further includes:
amplifying the voltage pulse signal;
and filtering the amplified voltage pulse signal.
By adopting the technical scheme, the problems of weak omission of voltage pulse signals and false detection of interference signals are solved, the accuracy of frequency value calculation results is further improved, and the reliability of mode locking results is improved.
Preferably, the determining the mode-locking state according to the frequency value includes:
judging whether the frequency value is within the first threshold value range;
if the frequency value is within the first threshold value range, judging whether the first quantity reaches a first preset threshold value, and if the frequency value reaches the first preset threshold value, judging that the mode locking state is successful; wherein the first number is a number of times the frequency value continues to be within the first threshold range;
if the frequency value is not within the range of the first threshold value, judging whether a second number reaches a second preset threshold value, and if the second number reaches the second preset threshold value, judging that the mode locking state is mode locking failure; wherein the second number is a number of times the frequency value is continuously out of the first threshold range.
By adopting the technical scheme, the mode locking state is judged every time, and the mode locking state is judged to be successful or failed only if the frequency value is continuously in or out of the range of the first threshold value reaches the first preset threshold value or the second preset threshold value, so that the detection result is obtained when the mode locking state is stable, and the reliability of the mode locking state judgment result is effectively improved.
Preferably, the determining the mode-locking state according to the frequency value includes:
judging whether the frequency value is within a first threshold value range;
if the frequency value is within the first threshold value range, judging whether the first identifier is in a successful preparation state, and if the first identifier is in the successful preparation state, judging that the mode locking state is successful in mode locking; wherein the frequency value is within the first threshold range, the first identifier being set to a successful readiness state;
if the frequency value is not within the first threshold value range, judging whether the first identifier is in a failure preparation state, and if the first identifier is in the failure preparation state, judging that the mode locking state is in mode locking failure; wherein the frequency value is not within the first threshold range, the first identifier is set to a fail-ready state.
By adopting the technical scheme, the frequency value is continuously judged for a plurality of times within or not within the first threshold value range by utilizing the first identifier, the frequency value is continuously obtained for at most two times, the frequency value can be ensured to be continuously obtained for at least two times within or not within the first threshold value range, and the mode locking state judgment speed is higher on the premise of ensuring the reliability of the mode locking state judgment result.
Preferably, before the adjusting the operating current of the laser according to the current adjusting signal, the method further includes:
acquiring current working current;
searching an unlocking record table according to the current working current, and searching an item of the unlocking current closest to the current working current; the unlocking record table comprises a plurality of entries, each entry comprises unlocking current and mode locking current, the unlocking current is working current when mode locking fails, and the mode locking current is working current when mode locking succeeds again after mode locking fails;
obtaining the mode locking current of the entry, and changing the working current to the mode locking current.
By adopting the technical scheme, the initial working current of the adjustment is closer to the working current of the mode locking again, the adjustment times are less when the working current is adjusted, and the mode locking speed is effectively improved.
In a second aspect, the present application provides a mold locking device, which adopts the following technical scheme:
a mode locking apparatus comprising:
the frequency detection module is used for acquiring the frequency value of the pulse laser; the pulse laser is collected at an output port of the laser or a seed light source of the laser;
the adjusting signal sending module is used for sending a current adjusting signal according to the frequency value; the frequency value is greater than a standard frequency to send a first signal, the frequency value is less than the standard frequency to send a second signal, and the standard frequency is the frequency of the output pulse laser when mode locking is successful;
the current processing module is used for adjusting the working current of the laser according to the current adjusting signal; wherein the operating current is reduced by a first step magnitude for the first signal and increased by a second step magnitude for the second signal;
and the mode locking state judging module is used for judging the mode locking state according to the frequency value obtained from the frequency detecting module, and if the mode locking state is successful, ending the mode locking.
By adopting the technical scheme, different current adjusting signals are sent according to the relationship between the laser pulse frequency and the standard frequency, the adjustment of working current is realized, the problem of lock losing caused by current drift is solved, the mode locking process is simple, the mode locking speed is high, and the mode locking device can be applied to any laser.
Preferably, the mode-locking state determining module is configured to determine the mode-locking state according to the frequency value by using a determination logic configured to:
the frequency value is within a first threshold value range and is within the first threshold value range continuously for multiple times, and the mode locking state is judged to be successful;
and if the frequency value is not in the first threshold range and is not in the first threshold range for a plurality of times continuously, judging that the mode locking state is mode locking failure.
Through adopting above-mentioned technical scheme, when carrying out mode locking state judgement, only when the laser instrument is in stable mode locking state, just carry out the mode locking state and detect for the mode locking is successful or the judgement that the mode locking failed, avoid appearing accidental error because of other steps in the judgement process, cause disconnected mode locking state erroneous judgement, effectively improve mode locking state result reliability, and the flow is simple, and judgement speed is fast to further improve the mode locking speed.
Preferably, the frequency detection module includes:
a photoelectric conversion unit for converting the pulse laser into a voltage pulse signal;
the detection unit is used for detecting the time interval between the rising edges of two adjacent voltage pulse signals;
and the first frequency calculation unit is used for calculating the frequency value of the voltage pulse signal according to the time interval and taking the frequency value of the voltage pulse signal as the frequency value of the pulse laser.
By adopting the technical scheme, the calculation speed of the voltage pulse signal frequency value is high, the accuracy and the reliability of the mode locking state judgment result are improved, and the mode locking state judgment speed is greatly improved, so that the mode locking speed is improved.
Preferably, the frequency detection module further includes:
a pulse amplification unit for amplifying the voltage pulse signal from the photoelectric conversion unit;
and the pulse filtering unit is used for filtering the voltage pulse signal from the pulse amplifying unit and sending the filtered voltage pulse signal to the detecting unit.
By adopting the technical scheme, the problems of weak omission of voltage pulse signals and false detection of interference signals are solved, the accuracy of frequency value calculation results is further improved, and the reliability of mode locking results is improved.
In a third aspect, the present application provides a laser, which adopts the following technical solution:
a laser comprising a mode locking device according to the second aspect.
By adopting the technical scheme, the laser can send different current adjusting signals according to the relationship between the laser pulse frequency and the standard frequency, so that the working current can be adjusted, the problem of lock losing caused by current drift is solved, the mode locking process is simple, and the mode locking speed is high.
In summary, the present application includes at least one of the following beneficial technical effects:
1. different current adjusting signals are sent according to the relationship between the laser pulse frequency and the standard frequency, so that the adjustment of working current is realized, the problem of lock losing caused by current drift is solved, the mode locking process is simple, and the mode locking speed is high;
2. before the working current is adjusted, the adjusted initial working current is changed into a current closer to the mode locking again through the unlocking record table, so that the adjustment times are reduced, and the mode locking speed is effectively improved;
3. the voltage pulse signal frequency value is obtained by detecting the time interval between the rising edges of two adjacent voltage pulse signals, the obtaining speed is high, the accuracy and the reliability of a mode locking state judgment result are improved, and the mode locking state judgment speed is greatly improved, so that the mode locking speed is improved.
Drawings
Fig. 1 is a flowchart of a mode locking method according to embodiment 1 of the present application.
Fig. 2 is a flowchart for determining the mode-locked state according to embodiment 2 of the present application.
Fig. 3 is a flowchart for determining the mode-locked state according to embodiment 3 of the present application.
Fig. 4 is a flowchart for determining the mode-locked state according to embodiment 4 of the present application.
Fig. 5 is a block diagram showing a structure of a mode locking device according to an embodiment of the present application.
Fig. 6 is a block diagram of a frequency detection module in the embodiment of the present application.
Fig. 7 is a block diagram of a frequency detection module according to another embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to fig. 1-7 and the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
The embodiment of the application discloses a mode locking method, which comprises the following steps:
acquiring a frequency value of the pulse laser; the pulse laser is collected at the output port of the laser or a seed light source of the laser;
transmitting a current adjustment signal according to the frequency value; the frequency value is greater than the standard frequency to send a first signal, the frequency value is less than the standard frequency to send a second signal, and the standard frequency is the frequency of outputting pulse laser when mode locking is successful;
adjusting the working current of the laser according to the current adjusting signal; wherein, when the current adjustment signal is a first signal, the working current is reduced according to a first further amplitude; when the current adjusting signal is a second signal, increasing the working current according to a second step amplitude;
and judging the mode locking state, and if the mode locking state is successful, ending the mode locking program.
Example 1.
Referring to fig. 1, as an embodiment of a mode locking method, a mode locking method may be applied to a laser or a mode locking apparatus to lock a laser, including the steps of:
s100, obtaining a frequency value of pulse laser; in this embodiment, a frequency value of the pulse laser is obtained, the pulse laser is subjected to photoelectric conversion, and since a frequency of a voltage pulse signal obtained by the conversion is the same as a frequency of the pulse laser, the frequency value of the voltage pulse signal is obtained by calculating the frequency value of the voltage pulse signal, and the frequency value of the pulse laser is obtained.
It should be noted that, if the laser is started or the mode-locking state is a mode-locking failure, step S100 is triggered to start execution, so that it can be ensured that the restarted laser or the laser with the failed mode-locking state is in a mode-locking success state.
Step S200, sending a current adjusting signal according to the frequency value; the frequency value is greater than the standard frequency to send a first signal, the frequency value is less than the standard frequency to send a second signal, the standard frequency is the frequency of the output pulse laser when the mode locking is successful, the standard frequency can be directly obtained from the laser, and the laser is factory setting.
Step S300, detecting the received current adjusting signal, and if the current adjusting signal is a first signal, executing step S400; if the signal is the second signal, step S500 is executed.
Step S400, reducing the working current according to the first further amplitude, and then performing step S600, wherein the adjusted working current cannot be less than the minimum working current of the laser seed light source.
Step S500, increasing the working current according to the second step amplitude, and then executing step S600, wherein the adjusted working current cannot be larger than the maximum working current of the laser seed light source.
It should be noted that the first step amplitude and the second step amplitude may be fixed values, or may be adjusted according to an absolute value of the frequency value of the pulse laser and the standard frequency difference, where the larger the absolute value of the difference is, the larger the first step amplitude and the second step amplitude are set, the smaller the absolute value of the difference is, the smaller the first step amplitude and the second step amplitude are set, and the first step amplitude and the second step amplitude may be the same or different.
Step S600, judging whether the mode locking state is successful, and if the mode locking state is successful, ending the mode locking program; if the mode locking fails, step S100 is executed to continue to obtain the frequency value of the pulse laser and start a new current adjustment.
In the digital circuit, in order to control the current adjustment through an IO interface without performing a false adjustment on the working current, in this embodiment, when the mode locking state is the mode locking success or the frequency value is equal to the standard frequency, the transmitted current adjustment signal is the third signal, and when step S300 is executed, if the detected current adjustment signal is the third signal, the working current is not adjusted. In this embodiment, the first signal is 00, the second signal is 11, and the third signal is 01, when performing detection, to avoid misjudgment, step S300 determines that the first signal is the first signal only if all detected signals in a preset period are high levels, all detected signals are low levels, and the second signal is the second signal, all detected signals are pulse signals, that is, accurate difference of three states is performed through time division multiplexing of high and low levels, so as to avoid misjudgment.
According to the embodiment, different current adjusting signals are sent according to the relationship between the laser pulse frequency and the standard frequency, the working current is adjusted, the problem of lock losing caused by current drift is solved, the mode locking process is simple, the mode locking speed is high, and the method can be applied to any laser.
Before executing step S300, the present embodiment further includes:
acquiring current working current;
searching an unlocking record table (such as an unlocking log which can be output and provides reference data for operation and maintenance personnel) according to the current working current, and searching an item where the unlocking current which is closest to the current working current (the absolute value of the difference between the current working current and the unlocking current is the closest to the current working current) is located; the unlocking record table comprises a plurality of entries, each entry comprises unlocking current and mode locking current, the unlocking current is working current when mode locking fails, and the mode locking current is working current when mode locking succeeds again after mode locking fails;
and obtaining the mode locking current of the entry, changing the working current into the mode locking current, adjusting the current on the basis of the changed working current when the step S300 is executed, updating the unlocking record table after the mode locking is successful, and recording the current unlocking current and the current mode locking current in one entry.
Thus, the changed working current is closer to the working current of the mode locking again, and when the working current is adjusted in the step S300, the adjustment times are less, and the mode locking speed is effectively improved.
Example 2.
In order to effectively improve the reliability of the mode locking state determination result and the mode locking speed and simplify the mode locking process, in this embodiment, as shown in fig. 2, the determining the mode locking state includes:
and step S611, acquiring the frequency value of the pulse laser.
Step S612, determining whether the frequency value is within a first threshold range, if so, performing step S613, otherwise, performing step S614.
In this embodiment, the maximum value of the first threshold range is the standard frequency value plus the error, and the minimum value of the first threshold range is the standard frequency minus the error; the standard frequency is a performance parameter of the laser, and the frequency of pulse laser output by the laser in a stable mode locking success state is marked and can be directly obtained on the laser; the error is an absolute value of a difference between a measurement frequency of the pulse laser and a standard frequency, the error is set according to precision requirements of different application scenes on the output of the pulse laser by the laser, and in a corresponding application scene, the error is allowed as long as the absolute value of the difference between the measurement frequency of the pulse laser and the standard frequency does not exceed the set corresponding error.
Step S613, judging whether the frequency value is continuously within the first threshold value range for multiple times, and if the frequency value is continuously within the first threshold value range for multiple times, judging that the mode locking state of the laser is successful; otherwise, the mode locking state is continuously judged according to the obtained voltage pulse signal frequency value.
Step S614, judging whether the frequency value is continuously and repeatedly out of the first threshold range, and if the frequency value is continuously and repeatedly out of the first threshold range, judging that the mode locking state of the laser is mode locking failure; otherwise, the mode locking state is continuously judged according to the obtained voltage pulse signal frequency value. In this embodiment, steps S612 to S614 are specific steps of determining the mode-locking state according to the frequency value.
In this embodiment, the mode-locking state detection step (step S611 to step S614 in this embodiment) for determining whether the mode-locking state is a new cycle is continued according to the obtained frequency value includes, but is not limited to, the following cases:
in the first case, after the specific steps of determining the mode-locking state according to the frequency value are executed (in this embodiment, steps S612 to S614), the pulse laser starts to be converted into the voltage pulse again, and a new mode-locking state detection step is performed (in this embodiment, steps S611 to S614);
in the second case, during the mode-locking state detection step, a new mode-locking state detection step is continuously performed.
When the mode locking state is judged by adopting the embodiment, the mode locking state is judged by utilizing whether the frequency value of the pulse laser is the same as the standard frequency, and the frequency value of the pulse laser is obtained for multiple times, so that whether the frequency value of the pulse laser is continuously and repeatedly the same as the standard frequency is judged, the mode locking state is judged to be the mode locking success detection or the mode locking failure only when the laser is in the stable mode locking state, the condition that the mode locking state is judged incorrectly due to accidental errors in other steps in the judging process is avoided, the mode locking state result reliability is effectively improved, the detection process is simple, and the detection efficiency is high.
In this embodiment, obtaining the frequency value of the pulsed laser includes:
the input pulse laser is converted into a voltage pulse signal.
In this embodiment, the pulse laser may be converted into a voltage pulse signal by a photodetector, or the pulse laser may be converted into a voltage pulse signal by a photodiode or other photoelectric conversion device, which is not specifically limited herein.
Acquiring a frequency value of the voltage pulse signal; in this embodiment, the manner of obtaining the frequency value of the voltage pulse signal includes, but is not limited to:
in the first mode, pulse counting is carried out on the voltage pulse signals within preset time, and the frequency value of the voltage pulse signals is obtained through calculation according to the obtained pulse number;
in the second mode, the time interval between the rising edges of two adjacent voltage pulse signals is detected; and calculating the frequency value of the voltage pulse signal according to the time interval. The frequency value is calculated by adopting the method, because only the time interval of the rising edges of two adjacent voltage pulse signals needs to be detected, compared with the method of counting the number of the voltage pulse signals in the preset time, the calculation speed is greatly improved, and the generally required time is nanosecond level or even smaller; in addition, in order to improve the accuracy and reliability of the mode locking state judgment result, the frequency value needs to be obtained for multiple times each time the mode locking state judgment is performed.
It should be noted that, pulse counting of the voltage pulse signal and detection of the time interval between two adjacent rising edges may be implemented by a high-speed counter; however, in order to ensure that stable and reliable counting and measuring results are obtained, in this embodiment, a CPLD, an FPGA, or other programmable logic circuits with better interference immunity and better accuracy are preferably selected to perform pulse counting on the voltage pulse signal and detect a time interval between two adjacent rising edges.
Because the voltage pulse signal obtained by photoelectric conversion is weak and has small amplitude, when pulse counting or time interval detection between adjacent rising edges is carried out, detection leakage easily occurs, so that the frequency value of the voltage pulse signal obtained by calculation is unreliable, and the mode locking state is misjudged; in order to further improve the reliability of mode locking state judgment and solve the problem of missing detection due to weak voltage pulse signals, in this embodiment, before the frequency value of the voltage pulse signal is obtained, the voltage pulse signal obtained by conversion is amplified (the amplitude value is increased) through an amplifying circuit, so that the voltage pulse signal is easy to detect; for example, the frequency of the voltage pulse signal is obtained through the FPGA programmable logic circuit, the FPGA is at a high level when detecting the voltage of more than 1.8V, and in order to ensure that the FPGA can not leak detection, the voltage pulse signal is firstly amplified to more than 1.8V through the amplifying circuit, so that the FPGA programmable logic circuit can accurately detect each voltage pulse signal.
In order to avoid the interference signal serving as the voltage pulse signal to be counted or detected, and to cause a large error in frequency value calculation, which leads to misjudgment in subsequent mode locking state judgment, in another embodiment, the amplified voltage pulse signal is shaped by a filter circuit, interference signals are filtered out, the signal subjected to frequency value detection is ensured to be an effective voltage pulse signal, the accuracy of a frequency value calculation result is further improved, and the reliability of a mode locking result is improved.
Example 3.
Compared with the embodiment 2, the implementation introduces a first preset threshold and a second preset threshold, the frequency value is continuously judged within or not within the first threshold for multiple times by utilizing the first preset threshold or the second preset threshold, and the mode locking state is judged to be successful or failed only when the frequency value is continuously judged within or not within the first threshold for multiple times to reach the first preset threshold or the second preset threshold every time the mode locking state is judged, so that the mode locking state is stable at the moment, the reliability of the mode locking state judgment result is effectively improved, and the stability of the mode locking system is improved. The method for determining the mode-locking state provided by this embodiment, as shown in fig. 3, includes the following steps:
and step S621, acquiring a frequency value of the pulse laser.
Step S622, determining whether the frequency value is within the first threshold range, if so, performing step S623, otherwise, performing step S625.
Step S623, adding 1 to the first quantity; wherein the first number is a number of times the frequency value continues to be within a first threshold range.
Step S624, judging whether the first quantity reaches a first preset threshold value, if so, indicating that the mode locking success state of the laser is stable, and judging that the current mode locking state of the laser is successful; otherwise, the mode locking state judgment is continuously judged according to the obtained voltage pulse signal frequency value.
In this embodiment, the first preset threshold is a positive integer, and the larger the value is, the more reliable the mode-locking state judgment result is, but the longer the mode-locking state judgment time is, so in order to ensure that the mode-locking state judgment is completed quickly, when the first preset threshold is set, the balance between the reliability and the efficiency of the mode-locking state judgment needs to be considered, generally, the first preset threshold is set to 4 and 5, and the reliability and the efficiency of the mode-locking state judgment are optimal; however, when the frequency is obtained by the second method, the first preset threshold is set to be within 10 times, the speed of mode locking state judgment is not obviously reduced, and the mode locking state judgment result is high in accuracy and speed.
Step S625, adding 1 to the second quantity, and setting the first quantity to zero; wherein the second number is the number of times the frequency value continues to be within the first threshold range.
Step S626, judging whether the second number reaches a second preset threshold value, if the second number reaches the second preset threshold value, indicating that the laser is in a mode locking failure state and is relatively stable, and judging that the current mode locking state of the laser is mode locking failure; otherwise, the mode locking state judgment is continuously judged according to the obtained voltage pulse signal frequency value.
In this embodiment, steps S622 to S626 are specific steps for determining the mode-locking state according to the frequency value, and steps S621 to S626 are steps for detecting the mode-locking state.
Example 4.
Compared with the embodiment 2, the embodiment introduces the first identifier, realizes the judgment that the frequency value is continuously in or out of the first threshold range for multiple times by using the first identifier, and the first identifier comprises two states of successful preparation and failed preparation; setting the first identifier to a successful prepare state when the frequency value is within a first threshold range; setting the first identifier to a fail-ready state when the frequency value is not within the first threshold range; in this embodiment, whether the frequency value is continuously determined for multiple times within the first threshold range or not is determined each time, and the frequency value is repeatedly obtained at most twice, but the frequency value is ensured to be continuously determined for at least two times within the first threshold range or not, so that the mode locking state determination speed is higher and the mode locking state determination speed is higher on the premise of ensuring the reliability of the mode locking state determination result, thereby improving the mode locking speed and reliability. The method for determining the mode-locking state provided by this embodiment, as shown in fig. 4, includes the following steps:
step S631 acquires a frequency value of the pulsed laser.
Step S632 is to determine whether the frequency value is within the first threshold range, if so, step S633 is executed, otherwise, step S635 is executed.
Step S633, judging whether the first identifier is in a successful preparation state, if so, indicating that the obtained voltage pulse signal frequency value is in a stable mode locking success state within a first threshold value range continuously for at least two times, and judging that the mode locking state of the laser is successful in mode locking; otherwise, step S634 is performed. For example, a first identifier of 1 indicates a successful preparation state, a first identifier of 0 indicates a failed preparation state, and when the first identifier is determined to be 1, when the first identifier is not newly set, it indicates that the frequency value obtained at least last time is within a first threshold range, that is, the frequency value is within the first threshold range at least twice consecutively, and it is determined that the mode-locking state of the laser is successful; when the first identifier is 0, it is described that the frequency value obtained last time is not within the first threshold range, and only this time is within the first threshold range, but not within the first threshold range for multiple times continuously, the stability of the mode locking success state cannot be determined, the frequency (voltage pulse signal) of the pulse laser is continuously obtained, and the mode locking state is determined.
And step S634, updating the first identifier to be in a successful preparation state, and continuously judging the mode locking state according to the frequency value of the acquired voltage pulse signal.
Step S635, determining whether the first identifier is in a failure preparation state, and if the first identifier is in the failure preparation state, indicating that the obtained voltage pulse signal frequency value is not within the first threshold range for at least two consecutive times, and is in a stable mode locking success state, and determining that the mode locking state of the laser is a mode locking failure; otherwise, step S636 is executed.
And step 636, updating the first identifier to be in a failure preparation state, and continuously judging the mode locking state according to the frequency value of the acquired voltage pulse signal.
In this embodiment, steps S632 to S636 are specific steps of determining the mode-locking state according to the frequency value; step S631 to step S636 are mode-locked state detection steps.
The embodiment of the application also discloses a mode locking device, which can be externally hung on the laser and used for locking the mode of the laser through the pulse laser output by the laser; the laser can also be internally arranged in the laser, and the laser is subjected to mode locking through pulse laser output by the laser seed light source; referring to fig. 5, includes:
the frequency detection module 10 is used for acquiring a frequency value of the pulse laser; the pulse laser is collected at an output port of the laser or a seed light source of the laser;
an adjusting signal sending module 20, configured to send a current adjusting signal according to the frequency value obtained by the frequency detection module 10; the frequency value is greater than a standard frequency to send a first signal, the frequency value is less than the standard frequency to send a second signal, and the standard frequency is the frequency of the output pulse laser when mode locking is successful;
the current processing module 30 is configured to adjust the working current of the laser according to the current adjustment signal; wherein for a first signal, the operating current is reduced according to a first step amplitude, and for a second signal, the operating current is increased according to a second step amplitude;
and a mode locking state determining module 40, configured to determine a mode locking state according to the frequency value obtained from the frequency detecting module 20 after the working current is adjusted, and if the mode locking state is successful, end the mode locking.
The mode locking device that this embodiment provided sends different current regulation signals according to laser pulse frequency and standard frequency magnitude relation, realizes operating current's adjustment, solves the out-of-lock problem that brings because of the current drift, and the mode locking flow is simple, and the mode locking is fast, and the mountable is on arbitrary laser instrument.
In this embodiment, the mode-locking state determining module 40 determines the mode-locking state according to the frequency value by the determining logic configured to:
the frequency value is within a first threshold value range, and is continuously within the first threshold value range for multiple times, and the mode locking state is judged to be successful;
and if the frequency value is not within the first threshold value range and is not within the first threshold value range for a plurality of times continuously, judging that the mode locking state is mode locking failure.
In this embodiment, the frequency value of the pulse laser is obtained by the frequency detection module 10, the mode-locking state determination module 40 determines the mode-locking state by using whether the frequency value of the pulse laser is the same as the standard frequency, and determines whether the frequency value of the pulse laser is the same as the standard frequency for multiple times, so as to ensure that the mode-locking state is determined as the mode-locking success or the mode-locking failure only when the laser is in the stable mode-locking state, thereby avoiding misjudgment of the mode-locking state due to accidental errors in other steps in the determination process, effectively improving the reliability of the result of the mode-locking state, having a simple detection process and high detection efficiency, and further improving the speed and reliability of.
The embodiment of the present application provides two ways for obtaining the frequency value of the voltage pulse signal for the frequency detection module 10, and the frequency detection module 10 corresponding to each way respectively is:
in a first mode, the frequency detection module 10 includes:
and the photoelectric conversion unit is used for converting the pulse laser into a voltage pulse signal.
The pulse counting unit is used for counting the pulses of the voltage pulse signals within preset time to obtain the number of the pulses;
and the second frequency calculation unit is used for calculating the frequency value of the voltage pulse signal according to the pulse number.
In a second mode, as shown in fig. 6, the frequency detection module 10 includes:
and a photoelectric conversion unit 11 for converting the pulse laser light into a voltage pulse signal.
And the detection unit 12 is used for detecting the time interval between the rising edges of two adjacent voltage pulse signals.
The first frequency calculating unit 13 is configured to calculate a frequency value of the voltage pulse signal according to the time interval.
As another embodiment of the mode-locking state detection apparatus, referring to fig. 7, the frequency detection module 10 further includes:
a pulse amplifying unit 14 for amplifying the voltage pulse signal from the photoelectric conversion unit 11 and transmitting the amplified voltage pulse signal.
In this embodiment, the pulse amplification unit 14 amplifies the weak voltage pulse signal obtained by the photoelectric conversion, so that the voltage pulse signal is easily detected, and missing detection is avoided, thereby affecting the accuracy of the mode locking state determination result. However, the frequency detection module 10 further includes:
and the pulse filtering unit 15 is configured to filter the voltage pulse signal from the pulse amplifying unit 14, and send the filtered voltage pulse signal to the frequency detection module 10. Therefore, after the voltage pulse signals are filtered, interference signals are filtered, the voltage pulse signals are shaped, the detected voltage pulse signals are guaranteed to be effective voltage pulse signals, the accuracy of frequency value calculation results is further improved, and the reliability of mode locking is improved.
In another embodiment of the present application, the mode-locking state determining module 40 determines the mode-locking state according to the frequency value, and the determining logic is configured to:
judging whether the frequency value is within a first threshold value range;
if the frequency value is within the first threshold value range, judging whether the first quantity reaches a first preset threshold value, and if so, judging that the mode locking state is successful; wherein the first number is the number of times the frequency value is continuously within a first threshold range;
if the frequency value is not within the range of the first threshold value, judging whether the second number reaches a second preset threshold value, and if the second number reaches the second preset threshold value, judging that the mode locking state is mode locking failure; wherein the second number is the number of times the frequency value is not within the first threshold range in succession.
In this embodiment, the first preset threshold or the second preset threshold is used to realize that the frequency value is continuously determined within or not within the range of the first threshold for multiple times, so that the mode-locking state determination result is output only when the mode-locking state is stable, and the reliability of the mode-locking state determination result is further improved.
In another embodiment of the present application, the mode-locking state determining module 40 determines the mode-locking state according to the frequency value, and the determining logic may further be:
judging whether the frequency value is within a first threshold value range;
if the frequency value is within the first threshold value range, judging whether the first identifier is in a successful preparation state, and if the first identifier is in the successful preparation state, judging that the mode locking state is successful; wherein the frequency value is within a first threshold range, the first identifier is set to a successful preparation state;
if the frequency value is not within the first threshold value range, judging whether the first identifier is in a failure preparation state, and if the first identifier is in the failure preparation state, judging that the mode locking state is in mode locking failure; wherein the frequency value is not within the first threshold range and the first identifier is set to a fail-ready state.
In this embodiment, the first identifier is used to determine whether the frequency value is continuously within the first threshold value range for multiple times, and whether the frequency value is continuously within the first threshold value range for multiple times or not is determined each time, and the frequency value is obtained repeatedly at most twice, but the frequency value can be ensured to be within the first threshold value range at least continuously twice or not, and on the premise of ensuring the reliability of the mode locking state determination result, the mode locking state determination speed is further increased, so that the mode locking speed is increased.
In addition, the embodiment of the application also discloses a laser, which comprises the mode locking device provided by the embodiment of the application; the photoelectric conversion unit of the mode locking device can obtain pulse laser from a seed light source of the laser and also can obtain the pulse laser from an output port of the laser.
The laser that this embodiment provided sends different current regulation signals according to laser pulse frequency and standard frequency size relation, realizes operating current's adjustment, solves the out-of-lock problem that brings because of the current drift, and the mode locking flow is simple, and the mode locking is fast.
The foregoing is a preferred embodiment of the present application and is not intended to limit the scope of the application in any way, and any features disclosed in this specification (including the abstract and drawings) may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.
Claims (12)
1. A method of mode locking, comprising:
acquiring a frequency value of the pulse laser; the pulse laser is collected at an output port of the laser or a seed light source of the laser;
sending a current adjusting signal according to the frequency value; the frequency value is greater than a standard frequency to send a first signal, the frequency value is less than the standard frequency to send a second signal, and the standard frequency is the frequency of the output pulse laser when mode locking is successful;
adjusting the working current of the laser according to the current adjusting signal; wherein the current adjustment signal is the first signal, the working current is reduced according to a first step amplitude, and the current adjustment signal is the second signal, the working current is increased according to a second step amplitude;
and judging the mode locking state, and if the mode locking state is successful, ending the mode locking program.
2. The mode locking method according to claim 1, wherein said determining the mode locking state comprises:
acquiring a frequency value of the pulse laser;
judging the mode locking state according to the frequency value; wherein:
the frequency value is within a first threshold value range and is within the first threshold value range continuously for multiple times, and the mode locking state is judged to be successful;
and if the frequency value is not in the first threshold range and is not in the first threshold range for a plurality of times continuously, judging that the mode locking state is mode locking failure.
3. The mode locking method according to claim 1 or 2, wherein said obtaining the frequency value of the pulsed laser includes:
converting the pulsed laser into a voltage pulse signal;
detecting the time interval between the rising edges of two adjacent voltage pulse signals;
and calculating the frequency value of the voltage pulse signal according to the time interval, and taking the frequency value of the voltage pulse signal as the frequency value of the pulse laser.
4. The mode-locking method according to claim 3, further comprising, before said obtaining the frequency value of the voltage pulse signal:
amplifying the voltage pulse signal;
and filtering the amplified voltage pulse signal.
5. The mode locking method according to claim 2, wherein said determining the mode locking state based on said frequency value comprises:
judging whether the frequency value is within the first threshold value range;
if the frequency value is within the first threshold value range, judging whether the first quantity reaches a first preset threshold value, and if the frequency value reaches the first preset threshold value, judging that the mode locking state is successful; wherein the first number is a number of times the frequency value continues to be within the first threshold range;
if the frequency value is not within the range of the first threshold value, judging whether a second number reaches a second preset threshold value, and if the second number reaches the second preset threshold value, judging that the mode locking state is mode locking failure; wherein the second number is a number of times the frequency value is continuously out of the first threshold range.
6. The mode locking method according to claim 2, wherein said determining the mode locking state based on said frequency value comprises:
judging whether the frequency value is within a first threshold value range;
if the frequency value is within the first threshold value range, judging whether the first identifier is in a successful preparation state, and if the first identifier is in the successful preparation state, judging that the mode locking state is successful in mode locking; wherein the frequency value is within the first threshold range, the first identifier being set to a successful readiness state;
if the frequency value is not within the first threshold value range, judging whether the first identifier is in a failure preparation state, and if the first identifier is in the failure preparation state, judging that the mode locking state is in mode locking failure; wherein the frequency value is not within the first threshold range, the first identifier is set to a fail-ready state.
7. The mode-locking method according to claim 1, further comprising, before said adjusting the operating current of the laser according to said current adjustment signal:
acquiring current working current;
searching an unlocking record table according to the current working current, and searching an item of the unlocking current closest to the current working current; the unlocking record table comprises a plurality of entries, each entry comprises unlocking current and mode locking current, the unlocking current is working current when mode locking fails, and the mode locking current is working current when mode locking succeeds again after mode locking fails;
obtaining the mode locking current of the entry, and changing the working current to the mode locking current.
8. A mold clamping apparatus, comprising:
the frequency detection module is used for acquiring the frequency value of the pulse laser; the pulse laser is collected at an output port of the laser or a seed light source of the laser;
the adjusting signal sending module is used for sending a current adjusting signal according to the frequency value; the frequency value is greater than a standard frequency to send a first signal, the frequency value is less than the standard frequency to send a second signal, and the standard frequency is the frequency of the output pulse laser when mode locking is successful;
the current processing module is used for adjusting the working current of the laser according to the current adjusting signal; wherein the operating current is reduced by a first step magnitude for the first signal and increased by a second step magnitude for the second signal;
and the mode locking state judging module is used for judging the mode locking state according to the frequency value obtained from the frequency detecting module, and if the mode locking state is successful, ending the mode locking.
9. The mode-locking apparatus according to claim 8, wherein said mode-locking state determining module determines the mode-locking state based on said frequency value by a determination logic configured to:
the frequency value is within a first threshold value range and is within the first threshold value range continuously for multiple times, and the mode locking state is judged to be successful;
and if the frequency value is not in the first threshold range and is not in the first threshold range for a plurality of times continuously, judging that the mode locking state is mode locking failure.
10. The mode locking apparatus according to claim 8, wherein said frequency detection module includes:
a photoelectric conversion unit for converting the pulse laser into a voltage pulse signal;
the detection unit is used for detecting the time interval between the rising edges of two adjacent voltage pulse signals;
and the first frequency calculation unit is used for calculating the frequency value of the voltage pulse signal according to the time interval and taking the frequency value of the voltage pulse signal as the frequency value of the pulse laser.
11. The mode locking apparatus according to claim 10, wherein said frequency detection module further comprises:
a pulse amplification unit for amplifying the voltage pulse signal from the photoelectric conversion unit;
and the pulse filtering unit is used for filtering the voltage pulse signal from the pulse amplifying unit and sending the filtered voltage pulse signal to the detecting unit.
12. A laser comprising the mode locking device according to any one of claims 8 to 11.
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| CN113300203A (en) * | 2021-07-26 | 2021-08-24 | 济南量子技术研究院 | Rapid mode locking method and system for optical frequency comb |
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