Optical frequency comb frequency stabilizing device and method

Abstract

The invention provides an optical frequency comb frequency stabilizing device and method, and the device comprises a first optical filter which is configured to carry out the filtering of an optical frequency comb, and obtains two comb teeth to be locked; the oscillation loop is configured to perform oscillation based on the two comb teeth to be locked and generate an oscillation radio frequency signal of a first angular frequency and an oscillation radio frequency signal of a second angular frequency; and the feedback controller is configured to perform frequency mixing processing on the oscillation radio frequency signal of the first angular frequency, the oscillation radio frequency signal of the second angular frequency and the radio frequency reference signal to extract an error signal changing along with time, and output a control signal based on the error signal to perform frequency locking on the optical frequency comb.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency stabilization of an optical frequency comb, and in particular to a frequency stabilization device and method for an optical frequency comb. Background Art

[0002] Optical frequency combs are widely used in signal generation, spectrum optics, length measurement and other fields. Their stability and frequency accuracy determine their performance in practical applications. Although the optical frequency comb of a traditional pulsed mode-locked laser has a wide spectrum, its frequency interval is usually less than 1 GHz. The method of generating an optical frequency comb by electro-optical phase modulation of continuous light has the advantages of adjustable comb tooth spacing, good optical comb performance, and relatively simple structure. The teeth of the electro-optically modulated optical frequency comb have good coherence, but the coherence of the generated high-order comb teeth will gradually deteriorate; the new microcavity optical frequency comb generation technology based on the optical Kerr effect has the potential huge advantages of compact device structure and easy integration, but its frequency stability is poor and frequency stability control is required. Summary of the invention

[0003] In view of the above problems, the present invention provides a frequency stabilization device and method for a base optical frequency comb.

[0004] According to a first aspect of the present invention, there is provided an optical frequency comb frequency stabilization device, comprising: a first optical filter, configured to filter an optical frequency comb to obtain two comb teeth to be locked; an oscillation loop, configured to oscillate based on the two comb teeth to be locked, to generate an oscillating radio frequency signal of a first angular frequency and an oscillating radio frequency signal of a second angular frequency; and a feedback controller, configured to mix the oscillating radio frequency signal of the first angular frequency, the oscillating radio frequency signal of the second angular frequency, and a radio frequency reference signal to extract an error signal that varies with time, and output a control signal based on the error signal to frequency lock the optical frequency comb.

[0005] According to an embodiment of the present invention, a feedback controller performs mixing processing on an oscillating radio frequency signal of a first angular frequency, an oscillating radio frequency signal of a second angular frequency, and a radio frequency reference signal to extract an error signal that varies with time, and outputs a control signal based on the error signal to frequency lock the optical frequency comb, including: mixing the oscillating radio frequency signal of the first angular frequency with the oscillating radio frequency signal of the second angular frequency and then filtering to obtain an oscillating radio frequency signal of a third angular frequency and an oscillating radio frequency signal of a fourth angular frequency, wherein the third angular frequency is the absolute value of the difference between the first angular frequency and the second angular frequency, and the fourth angular frequency is the sum of the first angular frequency and the second angular frequency; mixing the oscillating radio frequency signal of the third angular frequency with the radio frequency reference signal of the third angular frequency to extract a first error signal that varies with time, and mixing the oscillating radio frequency signal of the fourth angular frequency with the radio frequency reference signal of the fourth angular frequency to extract a second error signal that varies with time; and outputting a first control signal based on the first error signal and a second control signal based on the second error signal to frequency lock the optical frequency comb.

[0006] According to an embodiment of the present invention, an oscillation loop includes a first oscillation loop and a second oscillation loop; the first oscillation loop is a loop composed of an optical phase modulator, a second optical filter, a photodetector, a radio frequency power divider, a first radio frequency filter, a radio frequency amplifier, a radio frequency power divider, and a radio frequency combiner connected in sequence; the second oscillation loop is a loop composed of an optical phase modulator, a second optical filter, a photodetector, a radio frequency power divider, a second radio frequency filter, a radio frequency amplifier, a radio frequency power divider, and a radio frequency combiner connected in sequence; the first oscillation loop is configured to oscillate based on two comb teeth to be locked to generate an oscillating radio frequency signal of a first angular frequency, and the second oscillation loop is configured to oscillate based on two comb teeth to be locked to generate an oscillating radio frequency signal of a second angular frequency.

[0007] According to an embodiment of the present invention, the optical frequency comb is a microcavity optical frequency comb, and the feedback controller includes: a first mixer, configured to mix an oscillating radio frequency signal of a first angular frequency and an oscillating radio frequency signal of a second angular frequency to obtain a mixed signal; a radio frequency power divider, configured to split the mixed signal into a first sub-mixing signal and a second sub-mixing signal with equal power; a third radio frequency filter, configured to filter the first sub-mixing signal to obtain an oscillating radio frequency signal of a third angular frequency; a fourth radio frequency filter, configured to filter the second sub-mixing signal to obtain an oscillating radio frequency signal of a fourth angular frequency; and a second mixer, The optical frequency comb is configured to mix an oscillating radio frequency signal of a third angular frequency with an radio frequency reference signal of a third angular frequency to extract a first error signal that varies with time; the first feedback control module is configured to output a first control signal based on the first error signal to control the repetition angular frequency of the two comb teeth to be locked; the third mixer is configured to mix an oscillating radio frequency signal of a fourth angular frequency with an radio frequency reference signal of a fourth angular frequency to extract a second error signal that varies with time; the second feedback control module is configured to output a second control signal based on the second error signal to control the carrier envelope offset angular frequency of the optical frequency comb.

[0008] According to an embodiment of the present invention, the feedback controller also includes: a radio frequency divider, which is configured to divide the oscillating radio frequency signal of the third angular frequency and input it into the second mixer for mixing with the radio frequency reference signal of the third angular frequency, and to divide the oscillating radio frequency signal of the fourth angular frequency and input it into the third mixer for mixing with the radio frequency reference signal of the fourth angular frequency.

[0009] According to an embodiment of the present invention, the optical frequency comb is an electro-optically modulated optical frequency comb generated by a local oscillator laser and an electro-optical modulator, and the feedback controller includes: a first mixer, configured to mix an oscillating radio frequency signal of a first angular frequency and an oscillating radio frequency signal of a second angular frequency to obtain a mixed signal; a radio frequency power divider, configured to perform equal power beam splitting of the mixed signal into a first sub-mixing signal and a second sub-mixing signal; a third radio frequency filter, configured to filter the first sub-mixing signal to obtain an oscillating radio frequency signal of a third angular frequency; a fourth radio frequency filter, configured to filter the second sub-mixing signal to obtain an oscillating radio frequency signal of a fourth angular frequency; and a second mixer, configured to filter the second sub-mixing signal to obtain an oscillating radio frequency signal of a fourth angular frequency. The invention relates to a frequency converter, which is configured to mix the oscillating radio frequency signal of the third angular frequency with the radio frequency reference signal of the third angular frequency to extract a first error signal that varies with time; a first feedback control module, which is configured to output a first control signal based on the first error signal; a voltage-controlled oscillator, which is configured to output a signal of the corresponding angular frequency under the control of the first control signal; a third mixer, which is configured to mix the oscillating radio frequency signal of the fourth angular frequency with the radio frequency reference signal of the fourth angular frequency to extract a second error signal that varies with time; and a second feedback control module, which is configured to output a second control signal based on the second error signal to control the output frequency of the local oscillator laser.

[0010] According to an embodiment of the present invention, the feedback controller also includes: a radio frequency divider, which is configured to divide the oscillating radio frequency signal of the third angular frequency and input it into the second mixer for mixing with the radio frequency reference signal of the third angular frequency, and to divide the oscillating radio frequency signal of the fourth angular frequency and input it into the third mixer for mixing with the radio frequency reference signal of the fourth angular frequency.

[0011] According to an embodiment of the present invention, the first angular frequency and the second angular frequency are determined by the angular frequencies of the two comb teeth to be locked and the resonant angular frequency of the second optical filter.

[0012] According to an embodiment of the present invention, after the control signal is output based on the error signal to frequency lock the two comb teeth to be locked, a low phase noise microwave signal or a terahertz signal is output after frequency division by the optical frequency comb.

[0013] According to a second aspect of the present invention, there is provided an optical frequency comb frequency stabilization method based on the above-mentioned optical frequency comb frequency stabilization device, comprising: filtering the optical frequency comb through a first optical filter to obtain two comb teeth to be locked; inputting the two comb teeth to be locked into an oscillation loop to make the oscillation loop oscillate, thereby generating an oscillating radio frequency signal of a first angular frequency and an oscillating radio frequency signal of a second angular frequency, respectively; mixing the oscillating radio frequency signal of the first angular frequency, the oscillating radio frequency signal of the second angular frequency and a radio frequency reference signal through a feedback controller to extract an error signal that varies with time, and outputting a control signal based on the error signal to frequency lock the optical frequency comb.

[0014] The base optical frequency comb frequency stabilization device and method provided by the present invention have at least the following technical effects:

[0015] By processing the oscillation signal generated by the oscillation loop, an oscillating radio frequency signal of a first angular frequency and an oscillating radio frequency signal of a second angular frequency are obtained, and then mixed with a radio frequency reference signal to extract an error signal that varies with time. The error signal is output through a feedback controller to stably control the optical frequency comb.

[0016] For microcavity optical frequency combs, the repetition frequency and carrier envelope offset frequency can be locked to the same optical reference (the resonant angular frequency of the second filter) without requiring the optical frequency comb spectrum to cover a full octave. By locking the carrier envelope offset frequency and repetition frequency of the optical frequency comb to the same optical reference, the teeth of the locked optical frequency comb maintain a high degree of coherence, and a single comb tooth has a higher frequency stability.

[0017] Since the locked optical frequency comb has the same frequency stability as the optical filter, after locking, it can also output low phase noise microwave signals or terahertz signals that have been divided by the optical frequency comb. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0019] Figure 1 A schematic diagram showing the structure of an optical frequency comb frequency stabilization device according to an embodiment of the present invention;

[0020] Figure 2 A schematic diagram showing the structure of an optical frequency comb frequency stabilization device according to another embodiment of the present invention;

[0021] Figure 3 Schematically showing the spectrum graph corresponding to each signal in the frequency stabilization process of the optical frequency comb according to an embodiment of the present invention;

[0022] Figure 4 A schematic diagram showing the structure of an optical frequency comb frequency stabilization device according to yet another embodiment of the present invention;

[0023] Figure 5 The flowchart of the optical frequency comb frequency stabilization method according to an embodiment of the present invention is schematically shown. DETAILED DESCRIPTION

[0024] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] In the process of realizing the present invention, the applicant found that: for the electro-optically modulated optical frequency comb, the stability of the optical carrier and the RF drive signal of the electro-optical modulator jointly determine the stability of a single comb tooth, and the optical carrier frequency needs to be stabilized. The performance degradation of high-order comb teeth requires an RF drive signal with higher frequency stability or locking it to a more stable reference. For the microcavity optical frequency comb, the locking of the optical frequency comb can be achieved by locking two characteristic parameters (repetition frequency and carrier envelope offset frequency). When the repetition frequency of the optical frequency comb is within the electrical bandwidth, the repetition frequency can be directly extracted by its beat frequency, while the extraction of the carrier envelope offset frequency usually relies on self-reference technology. This technology requires that the optical frequency comb spectrum covers a complete octave, and the low-frequency comb is filtered out for frequency doubling, and the beat frequency is achieved with the high-frequency comb line to achieve the extraction of the carrier envelope offset frequency. The repetition frequency of the octave microcavity optical frequency comb in related technologies is greater than 200 GHz, far exceeding the electrical bandwidth; when the repetition frequency of the microcavity optical frequency comb approaches 20 GHz, its spectral bandwidth is significantly reduced, requiring subsequent amplification and spectral broadening to meet the octave bandwidth requirements.

[0029] In view of this, an embodiment of the present invention provides an optical frequency comb frequency stabilization device, which may include: a first optical filter, an oscillation loop and a feedback controller. The first optical filter is configured to filter the optical frequency comb to obtain two comb teeth to be locked. The oscillation loop is configured to oscillate based on the two comb teeth to be locked to generate an oscillating radio frequency signal of a first angular frequency and an oscillating radio frequency signal of a second angular frequency. The feedback controller is configured to mix the oscillating radio frequency signal of the first angular frequency, the oscillating radio frequency signal of the second angular frequency and a radio frequency reference signal to extract an error signal of the comb tooth frequency varying with time, and output a control signal based on the error signal to frequency lock the optical frequency comb to be locked.

[0030] The device generates an oscillating radio frequency signal through an oscillation loop, and a portion of the oscillating radio frequency signal is coupled outside the oscillation loop to lock the optical frequency comb to a stable optical reference, thereby achieving frequency stability control of the optical frequency comb.

[0031] The above optical frequency comb frequency stabilization device is introduced below in conjunction with specific embodiments.

[0032] Figure 1 The structure of an optical frequency comb frequency stabilization device according to an embodiment of the present invention is schematically shown.

[0033] like Figure 1 As shown, in an embodiment of the present invention, the oscillation loop includes a first oscillation loop and a second oscillation loop. The first oscillation loop is configured to oscillate based on one of the two comb teeth to be locked, generating an oscillation radio frequency signal of a first angular frequency, and the second oscillation loop is configured to oscillate based on the other of the two comb teeth to be locked, generating an oscillation radio frequency signal of a second angular frequency.

[0034] The feedback controller converts the oscillating RF signal of the first angular frequency (angular frequency is ), an oscillating RF signal of the second angular frequency (angular frequency is represented by The method comprises: mixing a frequency signal (represented by) with a radio frequency reference signal to extract an error signal that varies with time, and outputting a control signal based on the error signal to frequency lock the optical frequency comb, including:

[0035] The oscillating radio frequency signal of the first angular frequency is mixed with the oscillating radio frequency signal of the second angular frequency and then filtered to obtain an oscillating radio frequency signal of a third angular frequency and an oscillating radio frequency signal of a fourth angular frequency, wherein the third angular frequency is the absolute value of the difference between the first angular frequency and the second angular frequency, and the fourth angular frequency is the sum of the first angular frequency and the second angular frequency.

[0036] The oscillating RF signal of the third angular frequency is mixed with the RF reference signal of the third angular frequency to extract a first error signal that varies with time, and the oscillating RF signal of the fourth angular frequency is mixed with the RF reference signal of the fourth angular frequency to extract a second error signal that varies with time.

[0037] A first control signal is output based on the first error signal, and a second control signal is output based on the second error signal to frequency lock the optical frequency comb to be locked.

[0038] That is, in the feedback control loop, the oscillating RF signal is processed to generate an error signal, which is then output as a control signal after passing through a feedback controller, so that the carrier envelope offset angular frequency and the repetition angular frequency of the optical frequency comb are respectively locked with the optical reference.

[0039] Figure 2 The structure of an optical frequency comb frequency stabilization device according to another embodiment of the present invention is schematically shown.

[0040] like Figure 2 As shown, in an embodiment of the present invention, the optical frequency comb is a microcavity optical frequency comb.

[0041] The oscillation loop includes a first oscillation loop and a second oscillation loop. The first oscillation loop is a loop composed of an optical phase modulator, a second optical filter, a photodetector, a radio frequency power splitter, a first radio frequency filter, a radio frequency amplifier, a radio frequency power splitter, and a radio frequency combiner connected in sequence. The second oscillation loop is a loop composed of an optical phase modulator, a second optical filter, a photodetector, a radio frequency power splitter, a second radio frequency filter, a radio frequency amplifier, a radio frequency power splitter, and a radio frequency combiner connected in sequence.

[0042] The first oscillation loop is configured to oscillate based on one of the two comb teeth to be locked to generate an oscillating RF signal of a first angular frequency, and the second oscillation loop is configured to oscillate based on the other of the two comb teeth to be locked to generate an oscillating RF signal of a second angular frequency.

[0043] Feedback controllers may include:

[0044] The first mixer is configured to mix an oscillating radio frequency signal of a first angular frequency and an oscillating radio frequency signal of a second angular frequency to obtain a mixed signal.

[0045] The radio frequency power splitter is configured to split the mixed signal into a first sub-mixed signal and a second sub-mixed signal with equal power.

[0046] The third radio frequency filter is configured to filter the first sub-mixing signal to obtain an oscillating radio frequency signal of a third angular frequency.

[0047] The fourth radio frequency filter is configured to filter the second sub-mixing signal to obtain an oscillating radio frequency signal of a fourth angular frequency.

[0048] The second mixer is configured to mix the oscillating radio frequency signal of the third angular frequency with the radio frequency reference signal of the third angular frequency to extract a first error signal that varies with time.

[0049] The first feedback control module is configured to output a first control signal based on the first error signal to control the repetition angular frequency of the two comb teeth to be locked.

[0050] The third mixer is configured to mix the oscillating radio frequency signal of the fourth angular frequency with the radio frequency reference signal of the fourth angular frequency to extract a second error signal that varies with time.

[0051] The second feedback control module is configured to output a second control signal based on the second error signal to control the carrier-envelope offset angular frequency of the optical frequency comb to be locked.

[0052] Figure 3 The optical spectrum diagram corresponding to each signal in the frequency locking process of the optical frequency comb according to an embodiment of the present invention is schematically shown.

[0053] like Figure 3 As shown, for example, in the oscillation loop, after the optical frequency comb output passes through the optical filter, the angular frequencies are filtered out. and The two teeth of the comb (m, n are both positive integers) pass through the first oscillation loop and the second oscillation loop composed of an optical phase modulator, an optical filter, a photodetector, an RF power divider, a first RF filter, a second RF filter, an RF amplifier, an RF power divider and an RF combiner to generate angular frequencies of and The angular frequency of the oscillating RF signal is determined by the comb angular frequency input to the optical phase modulator. and The resonant angular frequency of the optical filter and The difference is determined by as well as The angular frequency of the oscillation is and The RF signal is sent to the feedback control part to stabilize the optical frequency comb. In the feedback control part, the angular frequency is and The RF signal is mixed by the mixer to produce an angular frequency of and The RF signal is divided into two paths by the power divider, and then filtered out by the RF filter with only the angular frequency component. and According to the frequency relationship described above, we can have , The angular frequency is After the RF signal is divided by (mn), it is mixed with the RF reference signal 1 with the same angular frequency to generate an error signal. After the error signal passes through the first feedback control module, the first control signal is output for feedback control of the repetition angular frequency of the optical frequency comb. The angular frequency is The RF signal is mixed with the RF reference with the same angular frequency, and the error signal generated is passed through the second feedback control module to generate a second control signal for stabilizing the carrier envelope offset angular frequency of the optical frequency comb. .

[0054] Based on the above embodiment, the feedback controller may further include:

[0055] The RF frequency divider is configured to divide the oscillating RF signal of the third angular frequency and input it into the second mixer for mixing with the RF reference signal of the third angular frequency, and divide the oscillating RF signal of the fourth angular frequency and input it into the third mixer for mixing with the RF reference signal of the fourth angular frequency. Before the RF signal is mixed with the RF reference to generate an error signal, the RF frequency divider is used to divide the frequency, which can reduce the difficulty of locking the feedback control path.

[0056] Figure 4 The structure of an optical frequency comb frequency stabilization device according to another embodiment of the present invention is schematically shown.

[0057] like Figure 4 As shown, in an embodiment of the present invention, the optical frequency comb is an electro-optically modulated optical frequency comb generated by a local oscillator laser and an electro-optic modulator.

[0058] The oscillation loop may include a first oscillation loop and a second oscillation loop. The first oscillation loop is a loop consisting of an optical phase modulator, a second optical filter, a photodetector, a radio frequency power splitter, a first radio frequency filter, a radio frequency amplifier, a radio frequency power splitter, and a radio frequency combiner connected in sequence. The second oscillation loop is a loop consisting of an optical phase modulator, a second optical filter, a photodetector, a radio frequency power splitter, a second radio frequency filter, a radio frequency amplifier, a radio frequency power splitter, and a radio frequency combiner connected in sequence.

[0059] The first oscillation loop is configured to oscillate based on one of the two comb teeth to be locked to generate an oscillating RF signal of a first angular frequency, and the second oscillation loop is configured to oscillate based on the other of the two comb teeth to be locked to generate an oscillating RF signal of a second angular frequency.

[0060] Feedback controllers may include:

[0061] A first mixer is configured to mix an oscillating radio frequency signal of a first angular frequency and an oscillating radio frequency signal of a second angular frequency to obtain a mixed signal;

[0062] A radio frequency power splitter is configured to split the mixed signal into a first sub-mixed signal and a second sub-mixed signal with equal power;

[0063] a third radio frequency filter, configured to filter the first sub-mixing signal to obtain an oscillating radio frequency signal of a third angular frequency;

[0064] a fourth radio frequency filter, configured to filter the second sub-mixing signal to obtain an oscillating radio frequency signal of a fourth angular frequency;

[0065] a second mixer configured to mix the oscillating radio frequency signal of a third angular frequency with the radio frequency reference signal of the third angular frequency to extract a first error signal varying with time;

[0066] A first feedback control module configured to output a first control signal based on a first error signal;

[0067] A voltage-controlled oscillator, configured to output a signal corresponding to an angular frequency under the control of a first control signal;

[0068] a third mixer configured to mix the oscillating radio frequency signal of a fourth angular frequency with the radio frequency reference signal of a fourth angular frequency to extract a second error signal varying with time;

[0069] The second feedback control module is configured to output a second control signal based on the second error signal to control the output frequency of the local oscillator laser.

[0070] Continue reading Figure 3 For example, the local oscillator laser generates a modulated optical frequency comb through an electro-optic modulator, and the RF signal driving the electro-optic modulator is generated by a voltage-controlled oscillator. The angular frequency of a single tooth of the electro-optic modulated frequency comb can be expressed as ,in , is the angular frequency of the local oscillator laser, is the angular frequency output by the voltage-controlled oscillator. After passing through the optical filter, the angular frequencies are filtered out as and The comb teeth, after passing through the oscillation loop, produce angular frequencies of and After mixing, the oscillating RF signal generates the sum of the angular frequencies of the oscillating signals and the difference between the angular frequencies, that is, and Among them, the angular frequency component is The signal is mixed with the RF reference with the same angular frequency to generate an error signal, which is used to output a first control signal to control the angular frequency of the output signal of the voltage-controlled oscillator after passing through the first feedback control module. The angular frequency component is The signal is mixed with a radio frequency reference with the same angular frequency to generate an error signal, which is used to output a second control signal to control the output frequency of the local oscillator laser after passing through a second feedback control module.

[0071] Furthermore, for the special case of m=0 or n=0, that is, one of the comb teeth used for locking is a local oscillator laser, the two RF signals generated by the oscillation can be directly mixed with the reference signal to obtain the error signal.

[0072] Furthermore, the feedback controller may also include:

[0073] The RF divider is configured to divide the oscillating RF signal of the third angular frequency and input it into the second mixer for mixing with the RF reference signal of the third angular frequency, and to divide the oscillating RF signal of the fourth angular frequency and input it into the third mixer for mixing with the RF reference signal of the fourth angular frequency.

[0074] exist Figure 1-Figure 4 On the basis of the optical frequency comb frequency stabilization device shown, since the locked optical frequency comb has the same frequency stability as the optical filter, the optical frequency comb frequency stabilization device can also output a low phase noise microwave signal or a terahertz signal after optical frequency comb division after stabilization.

[0075] It should be noted that the effect of repetition frequency locking of the optical frequency comb is related to the frequency interval between the comb teeth used for locking. The larger the frequency interval between the two optical frequency comb teeth used for locking, the higher the frequency stability between the comb teeth after locking.

[0076] Based on the above optical frequency comb frequency stabilization device, the present invention also provides an optical frequency comb frequency stabilization method. Figure 5 The optical frequency comb frequency stabilization method is described in detail.

[0077] Figure 5 The flowchart of the optical frequency comb frequency stabilization method according to an embodiment of the present invention is schematically shown.

[0078] like Figure 5 As shown, the optical frequency comb frequency stabilization method of this embodiment includes operations S510 to S530.

[0079] In operation S510, an optical frequency comb is filtered by a first optical filter to obtain two comb teeth to be locked.

[0080] In operation S520, two comb teeth to be locked are input into an oscillation loop to cause the oscillation loop to oscillate, thereby generating an oscillation radio frequency signal of a first angular frequency and an oscillation radio frequency signal of a second angular frequency, respectively.

[0081] In operation S530, the oscillating RF signal of the first angular frequency, the oscillating RF signal of the second angular frequency, and the RF reference signal are mixed by a feedback controller to extract an error signal that varies with time, and a control signal is output based on the error signal to frequency lock the optical frequency comb to be locked.

[0082] It should be noted that the specific implementation details and technical effects of the embodiment of the optical frequency comb frequency stabilization method are similar to or identical to those of the embodiment of the optical frequency comb frequency stabilization device, and will not be repeated here.

[0083] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems and methods according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram may represent a module, a program segment or a part of a code, and the above-mentioned module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0084] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways, even if such combinations and / or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention may be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All of these combinations and / or combinations fall within the scope of the present invention.

[0085] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination. The scope of the present invention is defined by the attached claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. An optical frequency comb frequency stabilization device, characterized in that: include: A first optical filter is configured to filter the optical frequency comb to obtain two comb teeth to be locked; an oscillation loop, configured to oscillate based on the two comb teeth to be locked, to generate an oscillation radio frequency signal of a first angular frequency and an oscillation radio frequency signal of a second angular frequency; The feedback controller is configured to mix the oscillating RF signal of the first angular frequency, the oscillating RF signal of the second angular frequency and a RF reference signal to extract an error signal that varies with time, and output a control signal based on the error signal to frequency lock the optical frequency comb.

2. The device according to claim 1, characterized in that The feedback controller performs mixing processing on the oscillating radio frequency signal of the first angular frequency, the oscillating radio frequency signal of the second angular frequency, and a radio frequency reference signal to extract an error signal that varies with time, and outputs a control signal based on the error signal to frequency lock the optical frequency comb, including: Mixing the oscillating radio frequency signal of the first angular frequency with the oscillating radio frequency signal of the second angular frequency and then filtering to obtain an oscillating radio frequency signal of a third angular frequency and an oscillating radio frequency signal of a fourth angular frequency, wherein the third angular frequency is the absolute value of the difference between the first angular frequency and the second angular frequency, and the fourth angular frequency is the sum of the first angular frequency and the second angular frequency; Mixing the oscillating radio frequency signal of the third angular frequency with the radio frequency reference signal of the third angular frequency to extract a first error signal that varies with time, and mixing the oscillating radio frequency signal of the fourth angular frequency with the radio frequency reference signal of the fourth angular frequency to extract a second error signal that varies with time; A first control signal is output based on the first error signal, and a second control signal is output based on the second error signal to frequency lock the optical frequency comb.

3. The device according to claim 1 or 2, characterized in that: The oscillation loop includes a first oscillation loop and a second oscillation loop; the first oscillation loop is a loop composed of an optical phase modulator, a second optical filter, a photodetector, a radio frequency power divider, a first radio frequency filter, a radio frequency amplifier, a radio frequency power divider, and a radio frequency combiner connected in sequence; the second oscillation loop is a loop composed of an optical phase modulator, a second optical filter, a photodetector, a radio frequency power divider, a second radio frequency filter, a radio frequency amplifier, a radio frequency power divider, and a radio frequency combiner connected in sequence; The first oscillation loop is configured to oscillate based on one of the two comb teeth to be locked to generate an oscillating RF signal of a first angular frequency, and the second oscillation loop is configured to oscillate based on the other of the two comb teeth to be locked to generate an oscillating RF signal of a second angular frequency.

4. The device according to claim 1 or 2, characterized in that: The optical frequency comb is a microcavity optical frequency comb, and the feedback controller comprises: A first mixer is configured to mix the oscillating radio frequency signal of the first angular frequency and the oscillating radio frequency signal of the second angular frequency to obtain a mixed signal; A radio frequency power splitter, configured to split the mixed signal into a first sub-mixed signal and a second sub-mixed signal with equal power; a third radio frequency filter, configured to filter the first sub-mixing signal to obtain an oscillating radio frequency signal of a third angular frequency; a fourth radio frequency filter, configured to filter the second sub-mixing signal to obtain an oscillating radio frequency signal of a fourth angular frequency; a second mixer configured to mix the oscillating radio frequency signal of the third angular frequency with a radio frequency reference signal of the third angular frequency to extract a first error signal varying with time; A first feedback control module is configured to output a first control signal based on the first error signal to control the repetition angular frequency of the two comb teeth to be locked; a third mixer configured to mix the oscillating radio frequency signal of the fourth angular frequency with the radio frequency reference signal of the fourth angular frequency to extract a second error signal varying with time; The second feedback control module is configured to output a second control signal based on the second error signal to control the carrier-envelope offset angular frequency of the optical frequency comb.

5. The device according to claim 4, characterized in that The feedback controller further comprises: The RF divider is configured to divide the oscillating RF signal of the third angular frequency and input the divided signal into the second mixer for mixing with the RF reference signal of the third angular frequency, and to divide the oscillating RF signal of the fourth angular frequency and input the divided signal into the third mixer for mixing with the RF reference signal of the fourth angular frequency.

6. The device according to claim 1 or 2, characterized in that: The optical frequency comb is an electro-optically modulated optical frequency comb generated by a local oscillator laser and an electro-optic modulator, and the feedback controller comprises: A first mixer is configured to mix the oscillating radio frequency signal of the first angular frequency and the oscillating radio frequency signal of the second angular frequency to obtain a mixed signal; A radio frequency power splitter, configured to split the mixed signal into a first sub-mixed signal and a second sub-mixed signal with equal power; a third radio frequency filter, configured to filter the first sub-mixing signal to obtain an oscillating radio frequency signal of a third angular frequency; a fourth radio frequency filter, configured to filter the second sub-mixing signal to obtain an oscillating radio frequency signal of a fourth angular frequency; a second mixer configured to mix the oscillating radio frequency signal of the third angular frequency with a radio frequency reference signal of the third angular frequency to extract a first error signal varying with time; A first feedback control module, configured to output a first control signal based on the first error signal; a voltage-controlled oscillator, configured to output a signal corresponding to an angular frequency under the control of the first control signal; a third mixer configured to mix the oscillating radio frequency signal of the fourth angular frequency with the radio frequency reference signal of the fourth angular frequency to extract a second error signal varying with time; The second feedback control module is configured to output a second control signal based on the second error signal to control the output frequency of the local oscillator laser.

7. The device according to claim 6, characterized in that The feedback controller further comprises: The RF divider is configured to divide the oscillating RF signal of the third angular frequency and input the divided signal into the second mixer for mixing with the RF reference signal of the third angular frequency, and to divide the oscillating RF signal of the fourth angular frequency and input the divided signal into the third mixer for mixing with the RF reference signal of the fourth angular frequency.

8. The device according to claim 3, characterized in that The first angular frequency and the second angular frequency are determined by the angular frequencies of the two comb teeth to be locked and the resonant angular frequency of the second optical filter.

9. The device according to claim 3, characterized in that After the control signal is output based on the error signal to frequency lock the two comb teeth to be locked, a low phase noise microwave signal or a terahertz signal is output after the optical frequency comb frequency division.

10. An optical frequency comb frequency stabilization method based on the optical frequency comb frequency stabilization device according to any one of claims 1 to 9, characterized in that: include: filtering the optical frequency comb through a first optical filter to obtain two comb teeth to be locked; Inputting the two comb teeth to be locked into an oscillation loop to make the oscillation loop oscillate, thereby generating an oscillation radio frequency signal of a first angular frequency and an oscillation radio frequency signal of a second angular frequency; The oscillating RF signal of the first angular frequency, the oscillating RF signal of the second angular frequency and the RF reference signal are mixed by a feedback controller to extract an error signal that varies with time, and a control signal is output based on the error signal to frequency lock the optical frequency comb.

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