Optical frequency comb frequency stabilization device and method

Abstract

This invention provides an optical frequency comb frequency stabilization device and method. The device includes: a first optical filter 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, generating an oscillation radio frequency signal at a first angular frequency and an oscillation radio frequency signal at a second angular frequency; and a feedback controller configured to perform mixing processing on the oscillation radio frequency signal at the first angular frequency, the oscillation radio frequency signal at the second angular frequency, and a radio frequency reference signal to extract a time-varying error signal, and output a control signal based on the error signal to lock the frequency of the optical frequency comb.

Description

Technical Field

[0001] This invention relates to the field of frequency stabilization technology for optical frequency combs, and more specifically to a frequency stabilization device and method for a basic optical frequency comb. Background Technology

[0002] Optical frequency combs are widely used in signal generation, spectral optics, length measurement, and other fields. Their stability and frequency accuracy determine their performance in practical applications. While traditional pulsed mode-locked laser optical frequency combs have a wide spectrum, their frequency spacing is typically less than 1 GHz. Optical frequency comb generation methods that use electro-optic phase modulation of continuous light offer advantages such as adjustable comb tooth spacing, good comb performance, and relatively simple structure. Electro-optic modulated optical frequency combs exhibit good coherence between the comb teeth, but the coherence of higher-order comb teeth gradually deteriorates. Novel microcavity optical frequency comb generation technologies based on the optical Kerr effect have significant potential advantages in terms of compact device structure and ease of integration, but their frequency stability is poor, requiring frequency stabilization control. Summary of the Invention

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

[0004] According to a first aspect of the present invention, an optical frequency comb frequency stabilization device is provided, comprising: a first optical filter 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 oscillating radio frequency signal at a first angular frequency and an oscillating radio frequency signal at a second angular frequency; and a feedback controller configured to perform mixing processing on the oscillating radio frequency signal at the first angular frequency, the oscillating radio frequency signal at the second angular frequency, and a radio frequency reference signal to extract a time-varying error signal, 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, the feedback controller performs frequency mixing processing on the oscillating radio frequency signal at a first angular frequency, the oscillating radio frequency signal at a second angular frequency, and the radio frequency reference signal to extract a time-varying error signal, and outputs a control signal based on the error signal to frequency lock the optical frequency comb. This includes: mixing the oscillating radio frequency signal at the first angular frequency with the oscillating radio frequency signal at the second angular frequency and then filtering them to obtain oscillating radio frequency signals at a third angular frequency and a fourth angular frequency, wherein the third angular frequency is the absolute value of the difference between the first and second angular frequencies, and the fourth angular frequency is the sum of the first and second angular frequencies; mixing the oscillating radio frequency signal at the third angular frequency with the radio frequency reference signal at the third angular frequency to extract a time-varying first error signal; mixing the oscillating radio frequency signal at the fourth angular frequency with the radio frequency reference signal at the fourth angular frequency to extract a time-varying second error signal; 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, 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, an RF power divider, a first RF filter, an RF amplifier, an RF power divider, and an RF combiner connected in sequence; the second oscillation loop is a loop composed of an optical phase modulator, a second optical filter, a photodetector, an RF power divider, a second RF filter, an RF amplifier, an RF power divider, and an RF combiner connected in sequence; the first oscillation loop is configured to oscillate based on the two comb teeth to be locked, generating an oscillating RF signal with a first angular frequency, and the second oscillation loop is configured to oscillate based on the two comb teeth to be locked, generating an oscillating RF signal with 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 at a first angular frequency and an oscillating radio frequency signal at a second angular frequency to obtain a mixed signal; a radio frequency power divider 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-mixed signal to obtain an oscillating radio frequency signal at a third angular frequency; a fourth radio frequency filter configured to filter the second sub-mixed signal to obtain an oscillating radio frequency signal at a fourth angular frequency; and a second mixer. The system is configured to mix a third-angular-frequency oscillating radio frequency signal and a third-angular-frequency radio frequency reference signal to extract a time-varying first error signal; a first feedback control module is configured to output a first control signal based on the first error signal to control the repetition frequency angular frequency of the two comb teeth to be locked; a third mixer is configured to mix a fourth-angular-frequency oscillating radio frequency signal and a fourth-angular-frequency radio frequency reference signal to extract a time-varying second error signal; and a 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 further includes: a radio frequency divider, configured to divide the oscillating radio frequency signal at a third angle frequency and input it into a second mixer to mix with a radio frequency reference signal at a third angle frequency, and to divide the oscillating radio frequency signal at a fourth angle frequency and input it into a third mixer to mix with a radio frequency reference signal at a fourth angle frequency.

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

[0010] According to an embodiment of the present invention, the feedback controller further includes: a radio frequency divider, configured to divide the oscillating radio frequency signal at a third angle frequency and input it into a second mixer to mix with a radio frequency reference signal at a third angle frequency, and to divide the oscillating radio frequency signal at a fourth angle frequency and input it into a third mixer to mix with a radio frequency reference signal at a fourth angle 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 frequency locking of the two comb teeth to be locked is performed by the output control signal based on the error signal, a low phase noise microwave signal or terahertz signal is output after frequency division by the optical frequency comb.

[0013] According to a second aspect of the present invention, an optical frequency comb frequency stabilization method based on the above-described optical frequency comb frequency stabilization device is provided, 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 oscillate the oscillation loop and generate an oscillation radio frequency signal at a first angular frequency and an oscillation radio frequency signal at a second angular frequency, respectively; performing a mixing process on the oscillation radio frequency signal at the first angular frequency, the oscillation radio frequency signal at 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 lock the frequency of the optical frequency comb.

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

[0015] By processing the oscillation signal generated by the oscillation loop, oscillation radio frequency signals with the first and second angular frequencies are obtained. These signals are then mixed with a radio frequency reference signal to extract an error signal that varies with time. The error signal is then used to stabilize the optical frequency comb by outputting a feedback controller signal.

[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 the optical frequency comb spectrum covering a full octave. Locking the carrier envelope offset frequency and repetition frequency of the optical frequency comb to the same optical reference ensures high coherence between the comb teeth, and each comb tooth exhibits higher frequency stability.

[0017] Since the locked optical frequency comb has the same frequency stability as the optical filter, it can also output low phase noise microwave signals or terahertz signals after being divided by the optical frequency comb. Attached Figure Description

[0018] The above-described features, other objects, and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0019] Figure 1 A schematic diagram of an optical frequency comb frequency stabilization device according to an embodiment of the present invention is shown.

[0020] Figure 2 A schematic diagram of an optical frequency comb frequency stabilizing device according to another embodiment of the present invention is shown.

[0021] Figure 3 The schematic diagram illustrates the spectrum of each signal during the frequency stabilization process of the optical frequency comb according to an embodiment of the present invention;

[0022] Figure 4 A schematic diagram of an optical frequency comb frequency stabilizing device according to yet another embodiment of the present invention is shown.

[0023] Figure 5 A flowchart illustrating an optical frequency comb frequency stabilization method according to an embodiment of the present invention is shown. Detailed Implementation

[0024] Hereinafter, 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 invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

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

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

[0028] In developing this invention, the applicant discovered that for electro-optic modulated optical frequency combs, the stability of a single comb tooth is jointly determined by the stability of the optical carrier and the radio frequency drive signal of the electro-optic modulator, requiring stabilization of the optical carrier frequency. Performance degradation of higher-order comb teeth necessitates radio frequency drive signals with higher frequency stability or locking them to a more stable reference. For microcavity optical frequency combs, locking can be achieved by using two characteristic parameters (repetition frequency and carrier envelope offset frequency). When the repetition frequency of the optical frequency comb is within the electrical bandwidth, its beat frequency can be directly extracted. However, the extraction of the carrier envelope offset frequency typically relies on self-reference techniques. This technique requires the optical frequency comb spectrum to cover a complete octave band, filtering out low-frequency combs for frequency doubling, and then beating with high-frequency comb lines to extract the carrier envelope offset frequency. The repetition frequencies of octave band microcavity optical frequency combs in related technologies are all greater than 200 GHz, which far exceeds the electrical bandwidth. When the repetition frequency of the microcavity optical frequency comb approaches 20 GHz, its spectral bandwidth decreases significantly, requiring subsequent amplification and spectral broadening to meet the octave band bandwidth requirement.

[0029] In view of this, embodiments of the present invention provide 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, generating an oscillating radio frequency signal at a first angular frequency and an oscillating radio frequency signal at a second angular frequency. The feedback controller is configured to perform mixing processing on the oscillating radio frequency signal at the first angular frequency, the oscillating radio frequency signal at the second angular frequency, and a radio frequency reference signal to extract an error signal indicating the frequency variation of the comb teeth over time, and output a control signal based on the error signal to lock the frequency of the optical frequency comb to be locked.

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

[0031] The frequency stabilization device of the optical frequency comb described above will be introduced below with reference to specific embodiments.

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

[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 oscillating radio frequency signal with a first angular frequency, and the second oscillation loop is configured to oscillate based on the other comb tooth to be locked, generating an oscillating radio frequency signal with a second angular frequency.

[0034] The feedback controller converts the oscillating radio frequency signal at the first angular frequency (angular frequency is used) into an oscillating radio frequency signal. (represented by) the second angular frequency oscillating radio frequency signal (angular frequency is expressed in terms of...) The optical frequency comb is frequency-locked by mixing the optical frequency comb with the radio frequency reference signal (represented by the signal) to extract the time-varying error signal. Based on the error signal, a control signal is output to lock the optical frequency comb at the correct frequency. This process includes:

[0035] The oscillating radio frequency signal at the first angular frequency is mixed with the oscillating radio frequency signal at the second angular frequency and then filtered to obtain the oscillating radio frequency signal at the third angular frequency and the oscillating radio frequency signal at the fourth angular frequency. 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 radio frequency signal at the third angle frequency and the radio frequency reference signal at the third angle frequency are mixed to extract the first error signal that varies with time. The oscillating radio frequency signal at the fourth angle frequency and the radio frequency reference signal at the fourth angle frequency are mixed to extract the second error signal that varies with time.

[0037] The first control signal is output based on the first error signal, and the second control signal is output based on the second error signal to perform frequency locking on the optical frequency comb to be locked.

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

[0039] Figure 2 A schematic diagram of an optical frequency comb frequency stabilizing device according to another embodiment of the present invention is 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 consisting of an optical phase modulator, a second optical filter, a photodetector, an RF power divider, a first RF filter, an RF amplifier, an RF power divider, and an RF combiner connected in sequence. The second oscillation loop is a loop consisting of an optical phase modulator, a second optical filter, a photodetector, an RF power divider, a second RF filter, an RF amplifier, an RF power divider, and an RF combiner connected in sequence.

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

[0043] The feedback controller may include:

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

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

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

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

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

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

[0050] The third mixer is configured to mix the fourth-angle frequency oscillating radio frequency signal and the fourth-angle frequency radio frequency reference signal to extract the time-varying second error signal.

[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 diagram illustrates the spectrum of each signal during the frequency locking process of the optical frequency comb according to an embodiment of the present invention.

[0053] like Figure 3 As shown, for example, in the oscillating loop, the output of the optical frequency comb passes through an optical filter, filtering out angular frequencies of... and The two comb teeth (m and n are both positive integers) pass through the first and second oscillation loops, which are 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, respectively generating angular frequencies of . and The oscillating radio frequency signal. The angular frequency of the oscillating radio frequency signal is determined by the comb tooth angular frequency input to the optical phase modulator. and Resonant angular frequency with optical filter and The difference determines, that is as well as The angular frequency generated by the oscillation is and The radio frequency signal is then fed into the feedback control section to stabilize the optical frequency comb. In the feedback control section, the angular frequency is... and The radio frequency signal is mixed by a mixer to produce an angular frequency of . and The radio frequency signal is split into two paths by a power divider, and then filtered by an radio frequency filter to extract the signals with only the angular frequency component. and Two radio frequency signals. Based on the frequency relationship described above, we can have... , The angular frequency is After being divided by (mn), the RF signal is mixed with the RF reference signal 1, which has the same angular frequency, to generate an error signal. The error signal passes through the first feedback control module and outputs a first control signal, which is used to control the repetition frequency angular frequency of the optical frequency comb. And the angular frequency is The radio frequency signal is mixed with a radio frequency reference at the same angular frequency. The resulting error signal is then processed by a second feedback control module to generate a second control signal used to stabilize the carrier envelope offset angular frequency of the optical frequency comb. .

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

[0055] The radio frequency (RF) divider is configured to divide the oscillating RF signal at the third angle frequency and then input it into the second mixer to mix with the RF reference signal at the third angle frequency. Similarly, it divides the oscillating RF signal at the fourth angle frequency and then inputs it into the third mixer to mix with the RF reference signal at the fourth angle frequency. Before the RF signal and RF reference generate an error signal during mixing, the RF divider reduces the difficulty of locking in the feedback control circuit.

[0056] Figure 4 The diagram schematically illustrates the structure of an optical frequency comb frequency stabilizing device according to yet another embodiment of the present invention.

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

[0058] The oscillation loop can 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, an RF power divider, a first RF filter, an RF amplifier, another RF power divider, and an RF combiner connected in sequence. The second oscillation loop is a loop consisting of an optical phase modulator, a second optical filter, a photodetector, an RF power divider, a second RF filter, an RF amplifier, another RF power divider, and an RF combiner connected in sequence.

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

[0060] The feedback controller may include:

[0061] The first mixer is configured to mix the oscillating radio frequency signal at a first angular frequency and the oscillating radio frequency signal at a second angular frequency to obtain a mixed signal;

[0062] The radio frequency power divider is configured to split the mixing signal into a first sub-mixing signal and a second sub-mixing signal with equal power.

[0063] The third radio frequency filter is configured to filter the first sub-mixer signal to obtain an oscillating radio frequency signal with a third angular frequency.

[0064] The fourth radio frequency filter is configured to filter the second sub-mixer signal to obtain an oscillating radio frequency signal with a fourth corner frequency;

[0065] The second mixer is configured to mix the oscillating radio frequency signal at the third angle frequency and the radio frequency reference signal at the third angle frequency to extract the first error signal that varies with time.

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

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

[0068] The third mixer is configured to mix the oscillating radio frequency signal at the fourth angle frequency with the radio frequency reference signal at the fourth angle frequency in order to extract the second error signal that varies 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, a local oscillator laser generates a modulation optical frequency comb via an electro-optic modulator, and the radio frequency signal driving the electro-optic modulator is generated by a voltage-controlled oscillator. The angular frequency of a single tooth of the electro-optic modulation frequency comb can be expressed as... ,in , This is the angular frequency of the local oscillator laser. This is the angular frequency output by the voltage-controlled oscillator. After passing through the optical filter, the angular frequencies are filtered out as follows: and The comb teeth, after passing through the oscillating loop, generate angular frequencies of... and The radio frequency signal. After mixing, the oscillating radio frequency signal generates components consisting of the sum of the angular frequencies and the difference between the angular frequencies of the oscillating signal, i.e. and The angular frequency component is... After the signal is mixed with an RF reference with the same angular frequency, an error signal is generated. This error signal, after passing through the first feedback control module, is used to output the first control signal to control the angular frequency of the voltage-controlled oscillator's output signal. The angular frequency component is... After the signal is mixed with the RF reference with the same angular frequency, an error signal is generated. After passing through the second feedback control module, it is used to output the second control signal to control the output frequency of the local oscillator laser.

[0071] Furthermore, for the special case of m=0 or n=0, where one of the comb teeth used for locking is a local oscillator laser, the error signal can be obtained by directly mixing the two radio frequency signals generated by the oscillation with the reference signal.

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

[0073] The radio frequency divider is configured to divide the oscillating radio frequency signal at the third angle frequency and input it into the second mixer to mix with the radio frequency reference signal at the third angle frequency, and to divide the oscillating radio frequency signal at the fourth angle frequency and input it into the third mixer to mix with the radio frequency reference signal at the fourth angle frequency.

[0074] exist Figures 1-4 Based on 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 terahertz signal after stabilization by the optical frequency comb.

[0075] It should be noted that the effect of frequency locking after optical frequency combing 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 aforementioned optical frequency comb frequency stabilization device, this invention also provides an optical frequency comb frequency stabilization method. The following will be combined with... Figure 5 The frequency stabilization method of this optical frequency comb is described in detail.

[0077] Figure 5 A flowchart illustrating an optical frequency comb frequency stabilization method according to an embodiment of the present invention is 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 of S510, the optical frequency comb is filtered by the first optical filter to obtain the two comb teeth to be locked.

[0080] When operating S520, the two comb teeth to be locked are input into the oscillation loop, causing the oscillation loop to oscillate and generate oscillation radio frequency signals at the first and second angular frequencies, respectively.

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

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

[0083] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0084] Those skilled in the art will understand that the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways, even if such combinations 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 can be combined or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

[0085] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. An optical frequency comb frequency stabilization apparatus, characterized by, The method comprises the steps of: a first optical filter configured to filter the optical frequency comb to obtain two teeth to be locked; an oscillation loop configured to oscillate based on the two 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; a feedback controller configured to mix the oscillation radio frequency signal of the first angular frequency, the oscillation radio frequency signal of the second angular frequency and a radio frequency reference signal to extract a time-varying error signal, and output a control signal based on the error signal to frequency lock the optical frequency comb; wherein the feedback controller mixes the oscillation radio frequency signal of the first angular frequency, the oscillation radio frequency signal of the second angular frequency and a radio frequency reference signal to extract a time-varying error signal, and outputs a control signal based on the error signal to frequency lock the optical frequency comb, comprising: mixing the oscillation radio frequency signal of the first angular frequency and the oscillation radio frequency signal of the second angular frequency and then filtering to obtain an oscillation radio frequency signal of a third angular frequency and an oscillation 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 oscillation radio frequency signal of the third angular frequency and a radio frequency reference signal of the third angular frequency to extract a first time-varying error signal, and mixing the oscillation radio frequency signal of the fourth angular frequency and a radio frequency reference signal of the fourth angular frequency to extract a second time-varying error signal; frequency locking the optical frequency comb based on the first control signal output by the first error signal and the second control signal output by the second error signal.

2. The apparatus of claim 1, wherein, The oscillation loop comprises 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 teeth to be locked to generate 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 teeth to be locked to generate an oscillation radio frequency signal of a second angular frequency.

3. The apparatus of claim 1, wherein, The optical frequency comb is a microcavity optical frequency comb, and the feedback controller comprises: a first frequency mixer configured to mix the oscillation radio frequency signal of the first angular frequency and the oscillation radio frequency signal of the second angular frequency to obtain a mixed signal; a radio frequency power divider 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-mixed signal to obtain an oscillation radio frequency signal of a third angular frequency; a fourth radio frequency filter configured to filter the second sub-mixed signal to obtain an oscillating radio frequency signal of a fourth angular frequency; a second frequency mixer configured to mix the oscillating radio frequency signal of the third angular frequency and a radio frequency reference signal of the third angular frequency to extract a first error signal varying over time; a first feedback control module configured to output a first control signal based on the first error signal to control the repetition angular frequency of the two combs to be locked; a third frequency mixer configured to mix the oscillating radio frequency signal of the fourth angular frequency and a radio frequency reference signal of the fourth angular frequency to extract a second error signal varying over time; a second feedback control module 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.

4. The apparatus of claim 3, wherein, The feedback controller further comprises: a radio frequency divider configured to input the oscillating radio frequency signal of the third angular frequency into the second frequency mixer after frequency division and mix with the radio frequency reference signal of the third angular frequency, and input the oscillating radio frequency signal of the fourth angular frequency into the third frequency mixer after frequency division and mix with the radio frequency reference signal of the fourth angular frequency.

5. The apparatus of claim 1, wherein, The optical frequency comb is an electro-optical modulation optical frequency comb generated by a local oscillator laser and an electro-optical modulator, and the feedback controller comprises: a first frequency mixer 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 divider configured to divide 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-mixed signal to obtain an oscillating radio frequency signal of a third angular frequency; a fourth radio frequency filter configured to filter the second sub-mixed signal to obtain an oscillating radio frequency signal of a fourth angular frequency; a second frequency mixer configured to mix the oscillating radio frequency signal of the third angular frequency and a radio frequency reference signal of the third angular frequency to extract a first error signal varying over 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 of a corresponding angular frequency under the control of the first control signal; a third frequency mixer configured to mix the oscillating radio frequency signal of the fourth angular frequency and a radio frequency reference signal of the fourth angular frequency to extract a second error signal varying over time; a second feedback control module configured to output a second control signal based on the second error signal to control the output frequency of the local oscillator laser.

6. The apparatus of claim 5, wherein, The feedback controller further comprises: a radio frequency divider configured to input the oscillating radio frequency signal of the third angular frequency into the second frequency mixer after frequency division and mix with the radio frequency reference signal of the third angular frequency, and input the oscillating radio frequency signal of the fourth angular frequency into the third frequency mixer after frequency division and mix with the radio frequency reference signal of the fourth angular frequency.

7. The apparatus of claim 2, wherein, The first angular frequency and the second angular frequency are determined by the angular frequency of the two combs to be locked and the resonant angular frequency of the second optical filter.

8. The apparatus of claim 2, wherein, After frequency locking of the two comb teeth to be locked based on the error signal output control signal, a low phase noise microwave signal or a terahertz signal frequency-divisional by the optical frequency comb is output.

9. An optical frequency comb frequency stabilization method based on the optical frequency comb frequency stabilization device of any one of claims 1-8, characterized in that, The method comprises the steps of: 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 to generate an oscillation radio frequency signal of a first angular frequency and an oscillation radio frequency signal of a second angular frequency; mixing the oscillation radio frequency signal of the first angular frequency, the oscillation radio frequency signal of the second angular frequency and a radio frequency reference signal through a feedback controller to extract a time-varying error signal, and frequency locking the optical frequency comb based on the error signal output control signal.

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