CN103633537B - The low noise optical-fiber laser frequency comb device that a kind of carrier_envelop phase offset frequency is controlled - Google Patents

Abstract

The present application provides a low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, which includes an optical path structure and a circuit structure, wherein the optical path structure includes an oscillator, an acousto-optic frequency shifter, a fiber amplifier, A pulse compressor, an optical fiber spread spectrum device and a coherent heterodyne beat frequency device; the circuit structure includes a front-feedback circuit controlling a phase device and a phase-locked loop circuit controlling a repetition frequency device. Among them, the fiber laser oscillator can ensure the long-term operation of the system, and the system stability is better than that of the solid-state laser oscillator; by optimizing the intracavity net dispersion of the fiber optic oscillator, introducing an intracavity modulator into the oscillator, and using front-feedback acousto-optic frequency shifting technologies such as devices to realize low-noise fiber laser frequency comb devices; at the same time, the use of acousto-optic frequency shifters can precisely control the carrier envelope phase shift frequency of optical frequency combs, thereby realizing optical frequency standards, attosecond science, non- Applications such as linear optics provide long-term stable optical frequency comb devices with precise phase manipulation.

Description

A low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency

technical field

The invention relates to the technical field of ultrafast fiber laser, in particular to a low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency.

Background technique

Femtosecond laser frequency comb is one of the most cutting-edge research contents in the field of ultrashort pulse laser. In the late 1990s, the proposal and realization of femtosecond titanium-sapphire-doped laser frequency comb revolutionized the optical frequency standard. In recent years, with the development of ultrashort-pulse fiber lasers, the advantages of fiber lasers such as compact structure and stable operation have gradually attracted people's attention to optical frequency combs based on fiber lasers. In 2002, the National Institute of Standards and Technology (NIST) of the United States reported for the first time the erbium-doped fiber laser frequency comb. In 2010, the American IMRA company also reported the realization of a high-power ytterbium-doped fiber frequency comb with an output power higher than 80W. So far, These fiber laser frequency combs have played an important role in the fields of optical frequency standards, precision spectroscopy research, laser ranging and astronomical detection.

However, compared with the Ti:Sapphire comb, the phase noise of the fiber laser frequency comb is relatively large. This is because the fiber laser is directly pumped by the semiconductor laser, and the semiconductor laser drive current ripple will introduce excessive noise, and the optical fiber There are many complex nonlinear effects, which further increase the phase noise of the fiber optic comb. In order to solve this problem, many effective methods have been proposed, such as stabilizing the intensity of the pumping current of the semiconductor laser, suppressing the current noise in it, and adjusting the dispersion in the fiber laser oscillator so that the net dispersion in the cavity is close to zero, which can effectively reduce Phase noise, and then use the electronic feedback control technology to further form a closed-loop control phase noise through the brake. The brake here can be a semiconductor drive power supply, a piezoelectric ceramic in the cavity, or an electro-optic modulator. Using these methods, a good phase noise is obtained. The noise suppression effect reduces the 3db linewidth of the carrier envelope phase shift frequency of the fiber frequency comb from the initial tens of megahertz to tens of kilohertz, which is basically close to the phase noise level of the titanium-sapphire frequency comb. However, the common disadvantage of these methods is that when the feedback circuit is used for locking, first, the proportional-integral (PI) loop of the phase-locked loop is required to perform time integration to obtain the control signal, and second, the carrier envelope phase shift frequency after locking is a fixed value , cannot be adjusted.

Therefore, we need a device that can realize real-time feed-forward control of the fiber optic comb, and realize a low-noise fiber optic frequency comb with controllable carrier envelope phase shift frequency while reducing the phase noise of the fiber optic comb.

Contents of the invention

The purpose of the present invention is to propose a low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, which can realize real-time feed-forward control of the fiber optic comb, and realize carrier envelope while reducing the phase noise of the fiber optic comb. Low-noise fiber-optic frequency comb with network phase-shift frequency controllable.

For reaching this purpose, the present invention adopts following technical scheme:

A low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, including an optical path structure and a circuit structure, wherein the optical path structure includes a fiber laser oscillator, an acousto-optic frequency shifter, a fiber amplifier, and a pulse compressor , optical fiber spread spectrum device and coherent heterodyne beat frequency device;

The fiber laser oscillator is used to generate femtosecond laser pulses. When the femtosecond laser pulses are transmitted to the acousto-optic frequency shifter, the zero-order diffracted light enters the fiber amplifier for at least one amplification, and the amplified laser enters the pulse The compressor performs pulse width compression, and the compressed laser enters the optical fiber spreading device for spectrum spreading, and the spread laser enters the coherent heterodyne beat frequency device for detection and obtains the carrier envelope phase-shifted frequency signal;

The circuit structure includes a front-feedback circuit control phase device and a phase-locked loop circuit control repetition frequency device;

The front feedback circuit control phase device is used to control and change the carrier envelope phase shift frequency of the femtosecond pulse, and mix the carrier envelope phase shift frequency measured above with the external frequency signal, and the obtained mixed frequency signal is amplified and directly output For the driver of the acousto-optic frequency shifter, the frequency of the first-order diffracted light of the acousto-optic frequency shifter is driven to change, thereby stabilizing and regulating the carrier envelope phase shift frequency of the femtosecond optical comb;

The repetition frequency phase-locked loop circuit is used to control the repetition frequency of femtosecond pulses. The photodetector is used to detect the output light of the oscillator to obtain the repetition frequency signal, and the signal and the external reference source signal are output to the phase-locked loop circuit at the same time. 1. The feedback control signal is obtained by proportional integral processing, and then the control signal is driven to the piezoelectric ceramic, and the cavity length is changed through the expansion and contraction of the piezoelectric ceramic, thereby locking the repetition frequency signal to a stable external frequency reference source.

As a preferred solution of the above-mentioned low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, the average power of the output pulse laser of the fiber laser oscillator is greater than 100mW, the output repetition frequency is greater than 200MHz, and the center of the output spectrum The wavelength is 1040nm, and the pulse width of the output laser is 1ps, which can reach below 50fs after passing through the pulse compressor.

As a preferred solution of the low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, the fiber laser oscillator further includes a dispersion control device, and the dispersion control device includes a reflection grating pair or a transmission grating pair.

As a preferred solution of the above-mentioned low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, the oscillator also includes an inner cavity modulator, and the inner cavity modulator is arranged in the oscillator cavity, and the The intracavity modulator is an electro-optic crystal modulator or a graphene modulator.

As a preferred solution of the above-mentioned low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, the fiber amplifier is composed of single-stage or multi-stage fiber amplification.

As a preferred solution of the above-mentioned low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, the fiber spectrum spreading device is a tapered fiber, and the tapered single-mode fiber uses a standard single-mode fiber. The middle part of the standard single-mode fiber is tapered. The core diameter of the tapered part of the final fiber is less than or equal to 4μm, the length of the tapered fiber is about 10cm, and the core diameter at both ends of the fiber is 8.2μm when not tapered.

As a preferred solution of the above-mentioned low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, the coherent heterodyne frequency beating device includes a dichroic mirror, a frequency doubling crystal, a low-pass filter, an avalanche diode, and a focusing lens and several laser high-reflective mirrors, the dichroic mirror divides the supercontinuum laser incident on the dichromatic mirror into two paths of short-wavelength band and long-wavelength band, adding optical path delay in the short-wavelength band optical path, and the two paths of light are returned through the high-reflective mirror respectively, and then After the high reflection mirror and lens focus on the frequency doubling crystal, the frequency doubling crystal doubles the frequency of the long-wavelength laser, and the two-way light passes through the low-pass filter to pass through the frequency-doubling light in the short-wave band and long-wave band in the optical path. For the transmission of other bands, the avalanche diode is placed behind the optical filter to detect the frequency doubled light in the long-wave band and the phase-shifted frequency signal of the carrier envelope generated by the beat frequency in the short-wave band.

As a preferred solution of the low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, the feedback-forward circuit control phase device includes a mixer and a filter amplifier, and the feed-forward circuit controls the phase device through a mixer. The frequency converter mixes the carrier envelope phase-shifted frequency signal with the external stable frequency reference source signal transformed by the frequency synthesizer, and then is filtered and amplified by the filter amplifier and then output to the acousto-optic frequency shifter.

As a preferred solution of the above-mentioned low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, the phase-locked loop circuit control repetition frequency device also includes a photodetection device, and the photodetector oscillates the detected fiber laser The high-order harmonics of the repeater frequency signal are directly input into the phase-locked loop circuit.

The beneficial effects of the present invention are: the present application provides a low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, which includes an optical path structure and a circuit structure, wherein the optical path structure includes a fiber laser oscillator, Acousto-optic frequency shifter, optical fiber amplifier, pulse compressor, optical fiber spread spectrum device and coherent heterodyne beat frequency device; the circuit structure includes a front-feedback circuit control phase device and a phase-locked loop circuit control repetition frequency device. Among them, the fiber laser oscillator can ensure the long-term operation of the system, and the system stability is better than that of the solid-state laser oscillator; by optimizing the intracavity net dispersion of the fiber optic oscillator, introducing an intracavity modulator into the oscillator, and using front-feedback acousto-optic frequency shifting technologies such as devices to realize low-noise fiber laser frequency comb devices; at the same time, the use of acousto-optic frequency shifters and mixers can precisely control the carrier envelope phase shift frequency of optical frequency combs, thereby realizing optical frequency standards, A Provide long-term stable optical frequency comb devices with precise phase control for applications such as second science and nonlinear optics.

Description of drawings

Fig. 1 is a schematic diagram of the structure of an optical frequency controllable low-noise fiber laser frequency comb according to an embodiment of the present invention;

2 is a schematic diagram of a high repetition rate, ring cavity fiber laser oscillator according to an embodiment of the present invention;

3 is a schematic structural view of a tapered highly nonlinear optical fiber according to an embodiment of the present invention;

4 is a schematic diagram of a coherent heterodyne beat frequency device according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of carrier envelope phase shift frequency locking according to an embodiment of the present invention.

in:

1: Fiber laser oscillator; 2: Acousto-optic frequency shifter; 3: Fiber amplifier; 4: Pulse compressor; 5: Optical fiber spread spectrum device; 6: Coherent heterodyne beat frequency device; 7: Front feedback circuit control phase device ; 8: Phase-locked loop circuit control repetition frequency device;

11: dispersion control device; 12: cavity modulator; 13: optical fiber part; 14: polarization mode-locking control device; 15: pump laser light source;

61: dichroic mirror; 62: frequency doubling crystal; 63: low-pass filter; 64: avalanche diode; 65: second highest mirror; 66: first highest mirror; 67: third highest mirror; 68: first A lens; 69: the second lens;

71: frequency synthesizer; 72: mixer; 73: filter amplifier.

detailed description

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

As shown in Figures 1-5, the present invention provides a low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, including an optical path structure and a circuit structure, wherein the optical path structure includes a fiber laser oscillator 1, an acoustic An optical frequency shifter 2, an optical fiber amplifier 3, a pulse compressor 4, an optical fiber spectrum spreading device 5 and a coherent heterodyne beat frequency device 6.

The fiber laser oscillator 1 is used to generate femtosecond laser pulses. When the femtosecond laser pulses are transmitted to the acousto-optic frequency shifter 2, the zero-order diffracted light enters the fiber amplifier 3 for at least one amplification, and the at least one amplified laser enters the pulse compression The pulse compression device 4 performs pulse compression, and the compressed laser light enters the fiber spectrum spreading device 5 for spectrum spreading, and the spread laser light enters the coherent heterodyne beat frequency device 6 for detection and obtains the carrier envelope phase-shifted frequency signal (f _ceo ) .

The circuit structure includes a feed-forward circuit to control the phase device 7 and a phase-locked loop circuit to control the repetition frequency device 8;

The front feedback circuit controls the phase device 7 to lock the f _ceo signal to an external stable frequency reference source and then output it to the acousto-optic frequency shifter 2;

The front feedback circuit control phase device 7 is used to control and change the carrier envelope phase shift frequency of the femtosecond laser pulse, and mix the carrier envelope phase shift frequency measured above with the external frequency signal, and the obtained mixed frequency signal is amplified Directly output to the driver of the acousto-optic frequency shifter 2 to drive the first-order diffracted light frequency of the acousto-optic frequency shifter 2 to change, thereby stabilizing and regulating the carrier envelope phase shift frequency of the femtosecond optical comb;

The phase-locked loop circuit controls the repetition frequency of the repetition frequency device 8. The repetition frequency phase-locked loop circuit is used to control the repetition frequency of the femtosecond pulse, uses the photodetector to detect the output light of the oscillator to obtain the repetition frequency signal ( _frep ), and compares the signal with the external The reference source signal is output to the phase-locked loop circuit at the same time, and the feedback control signal is obtained through phase detection and proportional integral processing, and then the control signal is driven to the piezoelectric ceramic, and the cavity length is changed through the expansion and contraction of the piezoelectric ceramic, thereby locking the repetition frequency signal to Stable external frequency reference source.

The average power of the output pulse laser of the fiber laser oscillator 1 is greater than 100mW, the output repetition frequency is greater than 200MHz, the central wavelength of the output spectrum is 1040nm, and the pulse width of the output laser is about 1ps, which can reach below 50fs after passing.

The fiber laser oscillator 1 includes a dispersion control device 11, and the dispersion control device 11 includes a pair of reflection gratings or a pair of transmission gratings. The fiber laser oscillator 1 also includes an inner cavity modulator 12, which is arranged in the cavity of the fiber laser oscillator 1, and the inner cavity modulator 12 is an electro-optic crystal modulator or a graphene modulator.

The above-mentioned fiber laser oscillator 1 also includes a pump laser light source 15 for providing energy.

More specifically, the fiber laser oscillator 1 is a high repetition rate fiber oscillator, and its structure is shown in Figure 2, which uses a standard nonlinear polarization rotation method to lock the mode. The whole fiber optic oscillator is divided into a fiber part 13 and a space optical path part, wherein the fiber part 13 includes a gain fiber and a common single-mode fiber. The gain fiber used has a gain greater than 350dB/m at a wavelength of 915nm and a length of about 20cm. Composed of single-mode optical fiber; the spatial optical route is composed of three parts: a dispersion control device 11, an inner cavity modulator 12 and a polarization mode-locking control device 14, wherein the dispersion control device 11 is composed of two reflection gratings or transmission gratings, and the grating line density is 600 lines per millimeter, the blaze wavelength is 1040nm, and the diffraction efficiency of the grating is greater than 85%; the typical intracavity modulator 12 uses an electro-optic modulator (EOM); the polarization mode-locking control device 14 is composed of a half-wave plate, a quarter It consists of a wave plate, a polarization beam splitter and a spatial optical isolator. By adjusting the dispersion control device 11, the entire fiber laser oscillator 1 can be mode-locked to operate near zero or near the polarization dispersion. By carefully adjusting the polarization components in the cavity, a stable mode-locked laser output can be realized at the vertical output end of the polarization beam splitter prism. , the repetition frequency of the mode-locked pulse is >200MHz, the output power is >100mW, the center wavelength is around 1040nm, and the output pulse width is about 1ps.

The pulse output by the fiber laser oscillator 1 enters the acousto-optic frequency shifter 2 through the focusing lens, wherein the negative first-order diffracted light of the acousto-optic frequency shifter 2 is output as the subsequent laser frequency comb, and the zero-order diffracted light passes through the optical fiber quasi- Straightener coupled into the fiber amplifier 3. The optical fiber amplifier 3 is composed of single-stage or multi-stage optical fiber amplification, and the average power of the amplified laser reaches the order of watts.

The pulse compressor 4 comprises a reflective grating pair or a transmissive grating. The amplified laser pulse is compressed by a high-efficiency reflection grating pair or a transmission grating pair. The grating line density is 1250 lines per mm, and the diffraction efficiency is greater than 90%. The grating pairs are placed in parallel, and the laser is incident on the grating at the Littrow angle. Above, after diffracted by the grating pair, turn back through the original path through the 0° high mirror, enter the grating pair again for the second compression, and then use the 45° high mirror to export the laser in the grating compressor, and finally obtain a pulse width of about 50fs Laser pulse output.

The optical fiber spectrum expansion device 5 is a tapered single-mode fiber, and the tapered single-mode fiber uses a standard single-mode fiber, and the middle part of the standard single-mode fiber is tapered, and the core diameter of the final fiber tapered part is Less than or equal to 4μm, the length of the tapered fiber is about 10cm, and the core diameter at both ends of the fiber is 8.2μm when not tapered, which can ensure a high coupling efficiency of spatial light to the fiber.

Further preferably, the compressed laser pulse is focused and coupled into a tapered high nonlinear fiber through an aspheric lens, and after the high nonlinear fiber spectrum is expanded, the supercontinuum spectrum range of the laser covers an octave or even wider, After collimation by the microscopic objective lens, the approximately parallel laser output is obtained, and the efficiency of coupling the entire space light to the highly nonlinear optical fiber is greater than 60%.

The coherent heterodyne frequency beating device 6 includes a dichroic mirror 61, a frequency doubling crystal 62, a low-pass filter 63, an avalanche diode 64, a focusing lens and some laser mirrors. Divided into two paths of short-wave band and long-wave band, adding optical path delay in the short-wave band optical path, the two paths of light are respectively turned back through the high reflection mirror, and focused on the frequency doubling crystal 62 through the high reflection mirror and lens 68, and the frequency doubling crystal 62 makes the long wave Band laser frequency doubling, the two-way light passes through the low-pass filter 63 to make the frequency-doubled light of the short-wave band and long-wave band in the optical path pass through and prevent the transmission of other bands, and the avalanche diode 64 is placed behind the low-pass filter 63 , which is used to detect the f _ceo signal generated by the frequency-doubled light in the long-wave band and the beat frequency in the short-wave band.

The specific propagation mode of the laser in the coherent heterodyne beat frequency device is: the supercontinuum laser is incident on the dichroic mirror 61, and the dichromatic mirror 61 transmits the wavelength range of 550nm to 950nm and reflects the wavelength range of 1050nm to 1500nm, so in the supercontinuum spectrum The long-wave band and the short-wave band are separated, and the second high reflection mirror 65 in the optical path of the transmitted laser (short-wave band) is installed on a translation platform, the main purpose is to provide a delay optical path, so that the pulse lasers of the long-wave band and the short-wave band overlap in time The separated two-way light is incident on the 45 ° third high reflection mirror 67 after the first high reflection mirror 66 backfolds, and then focuses on the frequency doubling crystal 62 through the first lens 68, and the second lens 69 aligns the light path Straight out, through the low-pass filter 63 incident on the avalanche diode 64. The above-mentioned first lens 68 and second lens 69 are focusing lenses, the first high-reflection mirror 66 is a near-infrared laser high-reflection mirror, the second high-reflection mirror 65 is a visible light laser high-reflection mirror, and the third high-reflection mirror 67 is silver-plated Laser high reflective mirror.

The frequency doubling crystal 62 of the laser in the coherent heterodyne beating device is to double the frequency of the laser in the long-wave band, and the frequency-doubling light produced is beat with the same wavelength components in the short-wave band of the supercontinuum spectrum, and the obtained signal is f _ceo signal; because the f _ceo signal is loaded in the short-wave component, it is necessary to use a low-pass filter 63 to filter out other wavelength components and only allow the short-wave component in a narrow range to pass through, so as not to introduce too much noise. At the same time, use a spectrum analyzer to observe the f _ceo signal, and optimize the grating pair spacing in the cavity of the fiber laser oscillator 1 and the fiber amplifier 3 by repeatedly adjusting the time delay line of the laser in the coherent heterodyne beat frequency device and the coincidence of the spatial light path Parameters such as laser power and laser polarization state incident on the spectrum expansion device 5 , until the signal-to-noise ratio of the f _ceo signal is higher than 30 dB and the line width is about 100 kHz.

The above are all the optical circuit parts of the low-noise fiber laser frequency comb device with controllable carrier envelope phase shift frequency, and the following are the feedback control and locking parts of the circuit:

The front feedback circuit control phase device includes a frequency synthesizer 71, a mixer 72 and a filter amplifier 73, and the front feedback circuit control phase device converts the f _ceo signal through the mixer 72 to an external stable frequency reference source transformed by the frequency synthesizer 71 The signals are mixed and then filtered and amplified by the filter amplifier 73 and then output to the acousto-optic frequency shifter 2 .

The phase-locked loop circuit control repetition frequency device 8 also includes a photodetector device, and the photodetector outputs the high-order harmonics of the _frep signal detected by the fiber laser oscillator 1 to the phase-locked loop circuit control repetition frequency of the laser oscillator The device 8 locks the repetition frequency signal to an external stable frequency reference source, and then outputs the control signal obtained by the phase-locked loop circuit to control the repetition frequency device 8 to the fiber laser oscillator 1 to control its repetition frequency.

There are two parameters that need to be locked in the whole system—the f _rep signal and the f _ceo signal. The locking method of the f _rep signal is shown in Figure 1: use a photodetector to detect the output light of the fiber laser oscillator 1 to obtain the f _rep signal And input its high-order harmonics into the phase-locked loop circuit control repetition frequency device 8, and simultaneously a stable external reference source is also input into the phase-locked loop circuit control repetition frequency device 8 as a reference standard, and the _frep signal is locked to on an external reference source.

The locking of the f _ceo signal mainly relies on the locking technology of the feedback circuit before the frequency shift of the acousto-optic frequency shifter 2. The specific principle and implementation steps are shown in Fig _. The external stable and frequency-variable reference source signal f _R transformed by the synthesizer 71 is mixed to obtain a mixed frequency signal f _ceo + f _R , and the mixed frequency signal is directly loaded to the acousto-optic frequency shifter 2 after filtering and amplifying; Secondly, the incident laser light (the optical frequency signal is f _ceo +n×f _rep ) generates zero-order diffracted light and negative first-order diffracted light through the acousto-optic frequency shifter 2, and in the negative-order diffracted light of the acousto-optic frequency shifter 2 , will carry the mixing signal loaded on the acousto-optic frequency shifter 2: -(f _ceo +f _R ), therefore, the output frequency of the negative order diffracted light of the acousto-optic frequency shifter 2 is the optical frequency signal and the mixing frequency The sum frequency of the signal, namely (f _ceo +n×f _rep )-(f _ceo +f _R )=n×f _rep -f _R , it can be known that the optical frequency signal of the negative first-order diffracted light does not contain f _ceo signal, but only contains the locked repetition frequency signal f _rep and the reference source signal f _R , when the frequency f _R of the external reference source transformed by the frequency synthesizer 71 is changed, the carrier envelope phase shift of the incident laser will be directly changed Frequency, so as to achieve the purpose of controlling the phase shift frequency of the carrier envelope of the optical frequency comb.

The carrier envelope phase shift frequency controllable low-noise fiber laser frequency comb device provided by this application has the following specific advantages: first, the high repetition frequency fiber oscillator system ensures that the energy of a single comb tooth of the output laser is higher and more It is suitable for applications that require high-energy comb teeth; secondly, through the optimization of the net dispersion in the fiber oscillator cavity, the use of intracavity modulators and feed-forward control locking, etc., a low-noise fiber frequency comb device is produced; thirdly, through The combination of an acousto-optic frequency shifter and a frequency mixer can achieve precise controllability of the carrier envelope phase shift frequency of the optical frequency comb; finally, the fiber frequency comb device based on the fiber oscillator makes the whole system run more stably and is used for long-term It has great advantages in fields such as time measurement.

The above describes the technical principles of the present invention in conjunction with specific embodiments. These descriptions are only for explaining the principles of the present invention, and cannot be construed as limiting the protection scope of the present invention in any way. Based on the explanations herein, those skilled in the art can think of other specific implementation modes of the present invention without creative efforts, and these modes will all fall within the protection scope of the present invention.

Claims (9)

1. the low noise optical-fiber laser frequency comb device that carrier_envelop phase offset frequency is controlled, including light Line structure and circuit structure, it is characterised in that described light channel structure includes fibre laser oscillator, acousto-optic Frequency shifter, fiber amplifier, pulse shortener, optical fiber spread spectrum device and relevant heterodyne beat device；

Described fibre laser oscillator is used for producing femto-second laser pulse, and described femtosecond laser pulse is extremely During acousto-optic frequency shifters, zero order diffracted light enters fiber amplifier and amplifies at least one times, through at least one times Laser after amplification enters pulse shortener and carries out Pulse Compression, and laser after compression enters optical fiber spread spectrum Device carries out spread spectrum, detects and obtain carrier wave bag in the laser light incident after spread spectrum to relevant heterodyne beat device Network phase shifting frequencies signal；

Described circuit structure includes that front feedback circuit controls phase device and phase-locked loop circuit controls to repeat frequency Rate device；

Front feedback circuit controls phase device for controlling and change the carrier envelope phase of femto-second laser pulse Shift frequency rate, is mixed the carrier_envelop phase offset frequency measured above with external reference source frequency, To the amplified driver being directly defeated by acousto-optic frequency shifters of mixed frequency signal, drive acousto-optic frequency shifters one-level Diffraction light frequency shift, thus play the stable and effect of regulation and control femtosecond light comb carrier_envelop phase offset frequency；

Repetition rate phase-locked loop circuit, for controlling the repetition rate of femtosecond pulse, uses photodetector to visit Survey agitator output light and obtain repetition rate signal, and the while of by this signal and external reference source frequency signal Export to phase-locked loop circuit, processed by phase demodulation, proportional integral and obtain feedback control signal, then should Control signal driving pressure electroceramics, long by the flexible change chamber of piezoelectric ceramics, thus repetition rate is believed Number lock onto stable external reference source.

The low noise optical-fiber laser frequency that carrier_envelop phase offset frequency the most according to claim 1 is controlled Rate carding device, it is characterised in that the mean power of the output laser pulse of described fibre laser oscillator is big In 100mW, output repetition rate is more than 200MHz, and the centre wavelength of output spectrum is 1040nm, Directly the pulse width of Output of laser is 1ps, can reach below 50fs after pulse shortener.

The low noise optical-fiber laser frequency that carrier_envelop phase offset frequency the most according to claim 2 is controlled Rate carding device, it is characterised in that described fibre laser oscillator also includes dispersion control device, described color Dissipate control device include reflecting grating to or transmission grating pair.

The low noise optical-fiber laser frequency that carrier_envelop phase offset frequency the most according to claim 3 is controlled Rate carding device, it is characterised in that described fibre laser oscillator also includes inner chamber manipulator, described inner chamber Manipulator is arranged in oscillator chamber body, and described inner chamber manipulator is electrooptical crystal modulator or Graphene Manipulator.

The low noise optical-fiber laser frequency that carrier_envelop phase offset frequency the most according to claim 1 is controlled Rate carding device, it is characterised in that described fiber amplifier is made up of single-stage or multi-stage fiber amplifier.

The low noise optical-fiber laser frequency that carrier_envelop phase offset frequency the most according to claim 1 is controlled Rate carding device, it is characterised in that optical fiber spread spectrum device for drawing bevel-type optical fiber, described in draw bevel-type single-mode fiber Use standard single-mode fiber, the mid portion of standard single-mode fiber is carried out optical fiber and draws cone, final light Fibre draws the core diameter of wimble fraction less than or equal to 4 μm, draws a length of about the 10cm of cone, optical fiber two ends 8.2 μm when core diameter is not draw cone.

The low noise optical-fiber laser frequency that carrier_envelop phase offset frequency the most according to claim 1 is controlled Rate carding device, it is characterised in that described relevant heterodyne beat device includes dichroic mirror, frequency-doubling crystal, low Pass filter sheet, avalanche diode, condenser lens and some laser high reflective mirrors, described dichroic mirror will incide The super continuous laser of dichroic mirror is divided into short-wave band and long wave band two-way, adds in short-wave band light path Light path time delay, two-way light turns back respectively through high reflective mirror, more brilliant to frequency multiplication through high reflective mirror and lens focus On body, frequency-doubling crystal makes long wave band laser freuqency doubling, after two-way light collimation, then is made by low pass filter Short-wave band and the frequency doubled light of long wave band in light path pass through and stop the transmission of other wave band, snowslide two After pole pipe is placed on optical filter, the frequency doubled light and short-wave band beat frequency for detecting long wave band produces Carrier_envelop phase offset frequency signal.

The low noise optical-fiber laser frequency that carrier_envelop phase offset frequency the most according to claim 1 is controlled Rate carding device, it is characterised in that described front feedback circuit controls phase device to be included frequency synthesizer, mix Frequently device and filter amplifier, described front feedback circuit controls phase device by frequency mixer by carrier envelope phase Move frequency signal to be mixed with the stable external reference source frequency signal through frequency synthesizer conversion, then warp Export to acousto-optic frequency shifters after crossing filter amplifier filter and amplification.

The low noise optical-fiber laser frequency that carrier_envelop phase offset frequency the most according to claim 1 is controlled Rate carding device, it is characterised in that phase-locked loop circuit controls repetition rate device and also includes Electro-Optical Sensor Set, Described photodetector is by direct for the higher hamonic wave of the fibre laser oscillator repetition rate signal detected It is input in phase-locked loop circuit.