CN111969399A - Pulse self-compression system based on Kagome hollow photonic crystal fiber and coupling adjustment method thereof - Google Patents
Pulse self-compression system based on Kagome hollow photonic crystal fiber and coupling adjustment method thereof Download PDFInfo
- Publication number
- CN111969399A CN111969399A CN202010712483.3A CN202010712483A CN111969399A CN 111969399 A CN111969399 A CN 111969399A CN 202010712483 A CN202010712483 A CN 202010712483A CN 111969399 A CN111969399 A CN 111969399A
- Authority
- CN
- China
- Prior art keywords
- photonic crystal
- crystal fiber
- kagome
- hollow
- hollow photonic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
- H01S3/06729—Peculiar transverse fibre profile
- H01S3/06741—Photonic crystal fibre, i.e. the fibre having a photonic bandgap
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/10007—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers
- H01S3/10015—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating in optical amplifiers by monitoring or controlling, e.g. attenuating, the input signal
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/102—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/105—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
- Optical Couplings Of Light Guides (AREA)
- Lasers (AREA)
Abstract
The invention provides a Kagome hollow photonic crystal fiber-based pulse self-compression system and a coupling adjustment method, and solves the problems that an existing femtosecond laser is not narrow enough in pulse width and cannot realize flexible transmission. The system comprises a near infrared high-reflection mirror pair, an attenuator, a focusing lens, a kagome hollow photonic crystal fiber with a protective outer layer and a vacuum unit for regulating the air pressure of an air cavity in the kagome hollow photonic crystal fiber, wherein the near infrared high-reflection mirror pair, the attenuator, the focusing lens, the kagome hollow photonic crystal fiber with the protective outer layer are sequentially arranged from left to right; the near-infrared high-reflection mirror pair is used for adjusting the femtosecond laser in the left-right direction and the height direction; the attenuator is used for carrying out power attenuation on the femtosecond laser; the focusing lens is used for adjusting the divergence angle and the spot size of the femtosecond laser beam; the inlet end and the outlet end of the kagome hollow photonic crystal fiber are respectively sealed through hollow fiber sealing heads; the first hollow optical fiber sealing head is arranged on the five-dimensional adjusting frame and used for vertical, front-back and left-right translation and height and left-right angle adjustment of the inlet end of the kagome hollow photonic crystal optical fiber.
Description
Technical Field
The invention belongs to the technical field of laser, relates to an ultrashort pulse self-compression technology, and particularly relates to a pulse self-compression system based on Kagome hollow photonic crystal fiber and a coupling adjustment method thereof.
Background
With the development of industrial femtosecond laser cold processing technology, the attention to the thermal effect in the ultrafast laser processing process is gradually increased, and compared with picosecond laser processing and nanosecond laser processing, the thermal effect in the hundreds of femtosecond high-energy ultrashort pulse processing process is obviously reduced, but in some extreme micropore processing processes, the requirement on the thermal effect is very strict, and a recast layer caused by the thermal effect still exists after hundreds of femtosecond laser processing, so that higher requirements are provided for the femtosecond laser light source with narrower pulse width. However, due to the limitation of the emission spectral bandwidth of the gain medium (for example, Yb fiber, Yb-doped crystal, etc. mainly used in the current ultra-short pulse amplification system), and the spectral bandwidth limitation of the transmission device in the amplification process, the spectral bandwidth is generally only several nm to ten and several nm, and the supported conversion limit pulse width is generally about several hundred femtoseconds to one picosecond, how to obtain the ultra-short pulse of tens of femtoseconds is an important challenge faced by the conventional laser. Meanwhile, for a processing machine tool, how to realize flexible transmission of an output light path has important significance for improving the processing breadth of the machine tool and reducing the size of the processing machine tool. However, the existing solid optical fiber is limited by various nonlinear effects such as self-focusing and the like and the limitation of damage threshold, cannot realize high-energy ultrashort pulse flexible transmission, and can only transmit by a spatial light path composed of reflectors. Meanwhile, flexibly transmitted high-energy ultrashort pulses have great application prospects in the field of laser medical treatment, and how to obtain narrower pulse width and flexible optical fiber transmission of light beams has great application requirements.
Disclosure of Invention
The invention provides a Kagome hollow photonic crystal fiber-based pulse self-compression system and a coupling adjustment method, aiming at solving the technical problems that the existing femtosecond laser is not narrow enough in pulse width and cannot realize flexible transmission.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a pulse self-compression system based on Kagome hollow photonic crystal fiber is characterized in that: defining the emergent direction of a femtosecond laser light source from left to right, wherein the system comprises a vacuum unit, a near-infrared high-reflection mirror pair, an attenuator, a focusing lens and a kagome hollow photonic crystal fiber with a protective outer layer, wherein the near-infrared high-reflection mirror pair, the attenuator, the focusing lens and the kagome hollow photonic crystal fiber are sequentially arranged from left to right;
the near-infrared high-reflection mirror pair is used for adjusting the femtosecond laser in the left-right direction and the height direction;
the attenuator comprises a first half-wave plate and a first polarization beam splitter prism which are coaxially arranged from left to right in sequence and are used for performing power attenuation on femtosecond laser;
the focusing lens is used for adjusting the divergence angle and the spot size of the femtosecond laser beam, so that the beam focused by the focusing lens is positioned on the end face of the inlet end of the kagome hollow photonic crystal fiber;
the inlet end and the outlet end of the kagome hollow photonic crystal fiber are respectively sealed through a first hollow fiber sealing head and a second hollow fiber sealing head, and the inner cavity of the first hollow fiber sealing head and the inner cavity of the second hollow fiber sealing head are both communicated with the inner air cavity of the kagome hollow photonic crystal fiber;
the sealing window sheet of the first hollow optical fiber sealing head, the sealing window sheet of the second hollow optical fiber sealing head, the focusing lens and the first polarization splitting prism are coaxially arranged;
the first hollow optical fiber sealing head is arranged on the five-dimensional adjusting frame and is used for translating the inlet end of the kagome hollow photonic crystal optical fiber in the vertical direction, the front-back direction and the left-right direction and adjusting the height and the left-right angle so as to realize the adjustment of the position and the angle of received incident light;
the vacuum unit is used for adjusting the air pressure of an air cavity inside the kagome hollow photonic crystal fiber.
Further, the near-infrared high-reflection mirror pair comprises a first mirror and a second mirror which are arranged in parallel; the included angle between the reflecting surface of the first reflecting mirror and the optical axis of the femtosecond laser light source is 45 degrees, and the included angle between the reflecting surface of the second reflecting mirror and the optical axis of the first half-wave plate is 45 degrees.
Further, the vacuum unit comprises a vacuum pump, a vacuum pipeline and a vacuum controller;
one end of the vacuum pipeline is communicated with the vacuum pump, and the other end of the vacuum pipeline is communicated with the inner cavity of the first hollow optical fiber sealing head or the inner cavity of the second hollow optical fiber sealing head;
the vacuum controller is arranged on the vacuum pipeline.
Further, the first hollow optical fiber sealing head comprises a pipeline, a vacuum shell, a gas sealing switch and a gas inlet and outlet interface which is used for being communicated with the vacuum pipeline;
the sealing window sheet is arranged at one end of the pipeline through the inlet flange; the other end of the pipeline is arranged on the vacuum shell through an outlet flange, and the inner cavity of the pipeline is communicated with the inner cavity of the vacuum shell;
the gas inlet and outlet interface is arranged on the outer wall of the vacuum shell and is communicated with the inner cavity of the vacuum shell;
the gas sealing switch is arranged on the gas inlet and outlet interface;
and the vacuum shell is provided with an optical fiber interface for connecting the kagome hollow photonic crystal fiber.
Further, the second hollow optical fiber sealing head is the same as the first hollow optical fiber sealing head in structure.
Further, the first hollow optical fiber sealing head further comprises a fixing plate;
the vacuum shell is arranged on the fixing plate;
the fixed plate is arranged on the five-dimensional adjusting frame.
Furthermore, the kagome hollow photonic crystal fiber has a core diameter of 57 μm, a numerical aperture NA of 0.03 and a length of 5 m.
Meanwhile, the invention provides a coupling adjustment method of the pulse self-compression system based on the Kagome hollow photonic crystal fiber, which is characterized by comprising the following steps of:
1) coarse adjustment of optical path
1.1) removing a focusing lens, and placing a CCD for detecting output laser at the outlet end of the kagome hollow photonic crystal fiber;
1.2) adjusting the light path direction of the incident laser by adopting a near-infrared high-reflection mirror until the light intensity measured by the CCD reaches the maximum;
2) fine adjustment of light path
2.1) installing a focusing lens, replacing the CCD with a photosensitive power meter, and ensuring that a focused light beam is positioned at the end face of the inlet end of the kagome hollow photonic crystal fiber after installing the focusing lens;
2.2) adjusting the position of the inlet end of the kagome hollow photonic crystal fiber by a five-dimensional adjusting frame until the output power value measured by the photosensitive power meter reaches the maximum value;
3) kagome hollow photonic crystal fiber air pressure adjustment
3.1) removing the photosensitive power meter, and sequentially installing a collimating lens, a second half-wave plate, a second polarization beam splitter prism and a thermosensitive power meter at the outlet end of the kagome hollow photonic crystal fiber from left to right;
meanwhile, a monitoring unit is arranged on a reflection light path of the second polarization beam splitter prism, and the monitoring unit comprises a spectrometer and an autocorrelator;
3.2) adjusting the position of the second half-wave plate until the transmitted light power of the second polarization splitting prism measured by the heat-sensitive power meter reaches the maximum;
3.3) starting the monitoring unit, testing the spectral width and the pulse width of the reflected light of the second polarization beam splitter prism, and adjusting the air pressure of an air cavity inside the kagome hollow photonic crystal fiber through the vacuum unit according to the tested spectral width and pulse width until the spectral broadening measured by the spectrometer reaches the set spectral width and the pulse measured by the autocorrelator reaches the set pulse width.
Compared with the prior art, the invention has the advantages that:
1. the pulse self-compression system realizes high-efficiency coupling of space light to the kagome hollow photonic crystal fiber by adopting a single-lens coupling mode, realizes nonlinear self-compression of high-energy ultrashort pulses by controlling the air pressure of the kagome hollow photonic crystal fiber through the vacuum unit, and can realize the output of ultrashort pulse flexible fibers with the original input pulse width of hundreds of fs and the narrowest output pulse width of tens of fs; the ultra-short pulse coupling output device has the characteristics of simple structure, low cost and no need of extra dispersion compensation, and can directly realize the coupling output of ultra-short pulses of dozens of femtoseconds.
2. The coupling adjusting method removes the focusing lens when adjusting the near-infrared high-reflection mirror pair, and prevents the damage to the end face of the kagome hollow photonic crystal fiber under the condition that the initial coupling is not adjusted; in the fine adjustment process, the CCD is replaced by a photosensitive power meter, so that the high-speed adjustment can be realized, and the characteristic of high adjustment precision is achieved; in the process of adjusting the air pressure of the air cavity inside the kagome hollow photonic crystal fiber, the position of the second half-wave plate is adjusted first, so that the transmission of the second polarization beam splitter prism is maximized, and the coupling efficiency can be better ensured; and then the reflected light of the polarization beam splitter prism is utilized to test the spectral change after coupling transmission, and the air pressure of the kagome hollow photonic crystal fiber is adjusted according to the tested spectral change, so that the output of high-energy ultrashort pulse of dozens of femtoseconds is realized, and the requirements of high-precision industrial cold machining on the pulse width of a laser light source and the requirements of high-energy physical aspect on the limit pulse width under extremely harsh conditions are met.
Drawings
FIG. 1 is a schematic diagram of a pulse self-compression system based on Kagome hollow photonic crystal fiber according to the present invention;
FIG. 2 is a schematic structural diagram of a first hollow fiber sealing head (a second hollow fiber sealing head) in a Kagome hollow photonic crystal fiber-based pulse self-compression system according to the present invention;
FIG. 3 is a schematic structural view of step 3) of the coupling adjustment method of the present invention;
FIG. 4 is a graph of fiber dispersion and transmission loss in the coupling adjustment method of the present invention; wherein, a is transmission loss, and b is optical fiber dispersion;
FIG. 5 is a graph of measured coupling efficiency curves in the coupling adjustment method of the present invention;
FIG. 6 is a graph of nonlinear spectral broadening in a coupling adjustment method of the present invention;
FIG. 7 is a graph of the original implant pulse width autocorrelation;
FIG. 8 is a graph of pulse width autocorrelation after transmission using the coupling adjustment method of the present invention;
wherein the reference numbers are as follows:
1-femtosecond laser light source, 2-first reflector, 3-second reflector, 4-first half wave plate, 5-first polarization beam splitter prism, 6-focusing lens, 7-kagome hollow photonic crystal fiber, 8-vacuum pump, 9-vacuum controller, 10-first hollow fiber sealing head, 101-sealing window plate, 102-inlet flange, 103-pipeline, 104-outlet flange, 105-vacuum shell, 106-gas inlet and outlet interface, 107-gas sealing switch, 109-fixing plate, 11-second hollow fiber sealing head, 12-collimating lens, 13-second half wave plate, 14-second polarization beam splitter prism, 15-heat-sensitive power meter, 16-monitoring unit and 17-vacuum pipeline.
Detailed Description
The invention is described in further detail below with reference to the figures and specific embodiments.
Aiming at the problems that the output pulse width of the existing femtosecond laser is limited by the emission spectrum width of a gain medium, the output pulse width is generally hundreds of femtoseconds to one picosecond, the requirement of high-precision industrial cold machining on the pulse width of a laser light source under extremely harsh conditions and the requirement of high-energy physics on the limit pulse width are met in order to further compress the pulse width, realize the output of high-energy ultrashort pulses of dozens of femtoseconds, and design a pulse self-compression system based on Kagome hollow photonic crystal fiber and a coupling adjustment method thereof.
As shown in figure 1, the Kagome hollow photonic crystal fiber-based pulse self-compression system defines the emergent direction of a femtosecond laser light source 1 from left to right, and comprises a near-infrared high-reflection mirror pair, an attenuator, a focusing lens 6, a Kagome hollow photonic crystal fiber 7 with a protective outer layer and a vacuum unit for adjusting the air pressure of an air cavity inside the Kagome hollow photonic crystal fiber 7, wherein the near-infrared high-reflection mirror pair, the attenuator, the focusing lens 6, the Kagome hollow photonic crystal fiber 7 and the vacuum unit are sequentially arranged from left to right along the emergent direction of the femtosecond.
The femtosecond laser light source 1 is an all-solid-state laser based on a chirped pulse amplification technology, the repetition frequency is 600kHz, the center wavelength is 1029nm, the spectrum width is about 10nm, the maximum output power is 20W, the output light is approximately collimated, the pulse width is 260fs, and the spot diameter is about 3 mm.
The near-infrared high-reflection mirror pair is a near-infrared high-reflection mirror pair, has two-dimensional adjusting functions in the height direction and the left-right direction, is used for realizing height and left-right adjustment of incident laser pulses and realizing coarse adjustment of the light path direction of the incident kagome hollow photonic crystal fiber 7. The near-infrared high-reflection mirror pair comprises a first reflection mirror 2 and a second reflection mirror 3 which are arranged in parallel, the included angle between the reflection surface of the first reflection mirror 2 and the optical axis of the femtosecond laser light source 1 is 45 degrees, the included angle between the reflection surface of the second reflection mirror 3 and the optical axis of the first half-wave plate 4 is 45 degrees, and the parameters of the first reflection mirror 2 and the second reflection mirror 3 are HR @1030 nm.
The attenuator comprises a 1030nm first half-wave plate 4 and a first polarization beam splitter prism 5 which are coaxially arranged from left to right in sequence and are used for performing power attenuation on incident light, and the power of the Kagome hollow photonic crystal fiber 7 during debugging is met.
The focal length of the focusing lens 6 is 100mm, and the focusing lens is used for adjusting the divergence angle and the light spot size of the femtosecond laser beam and realizing the control of the divergence angle and the light spot size of the beam injected into the kagome hollow photonic crystal fiber 7.
The kagome hollow photonic crystal fiber 7 has a core diameter of 57 μm, a numerical aperture NA of 0.03, a length of 5m, dispersion parameters and transmission losses at different wavelengths as shown in fig. 4, and it can be seen that the dispersion value provided for the transmitted 1030nm laser is negative. The inlet end and the outlet end of the kagome hollow photonic crystal fiber 7 are respectively sealed by a first hollow fiber sealing head 10 and a second hollow fiber sealing head 11, and the inner cavity of the first hollow fiber sealing head 10 and the inner cavity of the second hollow fiber sealing head 11 are both communicated with the inner air cavity of the kagome hollow photonic crystal fiber 7; as shown in fig. 2, the first hollow fiber sealing head 10 includes a sealing window sheet 101, a pipe 103, a vacuum housing 105, a gas inlet/outlet interface 106 and a gas sealing switch 107; the sealing window sheet 101 is a laser high lens sheet with a wave band of 1um, and the sealing window sheet 101 is arranged at one end of the pipeline 103 through an inlet flange 102; the other end of the pipeline 103 is arranged on the vacuum shell through an outlet flange 104, and the inner cavity of the pipeline 103 is communicated with the inner cavity of the vacuum shell; the gas inlet and outlet interface 106 is arranged on the outer wall of the vacuum shell and is communicated with the inner cavity of the vacuum shell; the gas sealing switch 107 is arranged on the gas inlet and outlet interface 106; the vacuum shell is also provided with a belt optical fiber interface. The second hollow fiber sealing head 11 has the same structure as the first hollow fiber sealing head 10 and is symmetrically distributed by the kagome hollow photonic crystal fiber 7; the sealing window sheet 101 of the first hollow optical fiber sealing head 10, the sealing window sheet 101 of the second hollow optical fiber sealing head 11, the focusing lens 6 and the first polarization splitting prism 5 are coaxially arranged.
The gas inlet and outlet interface 106 of the first hollow optical fiber sealing head 10 is communicated with the vacuum unit, and the gas sealing switch 107 of the second hollow optical fiber sealing head 11 is in a closed state; the inlet end and the outlet end of the kagome hollow photonic crystal fiber 7 are respectively connected to the fiber interface of the first hollow fiber sealing head 10 and the fiber interface of the second hollow fiber sealing head 11; that is, the inlet end of the kagome hollow photonic crystal fiber 7 is in an open state, and the outlet end of the kagome hollow photonic crystal fiber 7 is in a closed state, so that air can be pumped, nonlinear effects (such as self-phase modulation and soliton self-frequency shift) in the kagome hollow photonic crystal fiber 7 are reduced, and femtosecond transmission and nonlinear self-compression of larger energy are realized. In other embodiments, the gas inlet/outlet port 106 of the second hollow fiber sealing head 11 may be connected to the vacuum unit, and the gas sealing switch 107 of the first hollow fiber sealing head 10 is in a closed state, that is, the inlet end of the kagome hollow photonic crystal fiber 7 is in a closed state, and the outlet end is in an open state, to be connected to the vacuum unit.
In this embodiment, the kagome hollow photonic crystal fiber 7 is sealed by the sealing window sheet 101, and is equipped with the gas inlet/outlet interface 106 and the gas sealing switch 107, the gas sealing switch 107 can adjust and maintain the internal gas pressure of the kagome hollow photonic crystal fiber 7, and the gas can be pumped or inflated to control the nonlinear control of the ultrashort pulse laser with different incident parameters; meanwhile, the first hollow optical fiber sealing head 10 is fixed on a five-dimensional adjusting frame, so that three-dimensional translation and angle adjustment of the height and the left and the right of the inlet end of the kagome hollow photonic crystal fiber 7 in the vertical direction, the front and the back direction and the left and the right direction can be realized, the fact that the light beam of the incident laser is located on the end face of the fiber is guaranteed, and the best position and angle for receiving the incident light are realized.
For the convenience of adjustment, the first hollow fiber sealing head 10 further includes a fixing plate 109; the vacuum housing is disposed on the fixing plate 109; the fixing plate 109 is mounted on a five-dimensional adjusting bracket.
The vacuum unit comprises a vacuum pump 8, a vacuum pipeline 17 and a vacuum controller 9; one end of the vacuum pipeline 17 is communicated with the vacuum pump 8, and the other end is communicated with the gas inlet and outlet interface 106 of the first hollow optical fiber sealing head 10; the vacuum controller 9 is arranged on the vacuum pipeline 17; the vacuum controller 9 can realize the air pressure control of 1100-1mbar, and the vacuum pump 8 can realize the vacuum pumping capacity of 1mbar with minimum air pressure.
The coupling adjustment method of the pulse self-compression system comprises the following steps:
1) coarse adjustment of optical path
The output laser of the femtosecond laser light source 1 adopts the first reflector 2 and the second reflector 3 of the near-infrared high-reflection mirror to realize the rough adjustment of a light path of the Kagome hollow photonic crystal fiber 7, and the first half-wave plate 4 and the first polarization beam splitter prism 5 attenuate the power of the incident light, so that the power of the incident Kagome hollow photonic crystal fiber 7 is only a few mW to dozens of mW, and the damage to the end face of the Kagome hollow photonic crystal fiber 7 under the condition that the initial coupling is not adjusted is avoided. In the adjusting process, the end face of the inlet end of the kagome hollow photonic crystal fiber 7 can be reached through a few mW to dozens of mW without adding the focusing lens 6, a high-sensitivity CCD is added at the outlet end of the kagome hollow photonic crystal fiber 7 for detecting output laser, the first hollow optical fiber sealing head 10 is fixed on a five-dimensional adjusting frame, and the rough adjustment of coupling is completed through adjusting the light intensity obtained by testing the enhanced CCD;
2) fine adjustment of light path
And a focusing lens 6 is installed, the distance added by the focusing lens 6 basically meets the condition that a light beam focused by the lens is positioned at the end face of the inlet end of the kagome hollow photonic crystal fiber 7, and four dimensions (x, Y, theta x and theta Y) of a five-dimensional adjusting frame are adjusted to increase the light intensity on the CCD, wherein x is the left-right direction, Y is the up-down direction, theta x is the angle of the left-right direction, and theta Y is the angle of the high-low direction. In order to realize high-speed regulation response, a CCD is changed into a photosensitive power meter with a range covering a few mW to dozens of mW, the relative position of laser output and the inlet end face of the kagome hollow photonic crystal fiber 7 is precisely regulated by regulating the z (front and back) direction, the change of the power meter is observed, the front and back direction is determined, the power meter continuously moves towards the direction of power increase, the optimal power is optimized in four dimensions of (x, Y, theta x and theta Y) every time the power meter moves for dozens of micrometers, and the optimal power is repeatedly approached until the output power value reaches the maximum;
3) kagome hollow photonic crystal fiber 7 air pressure adjustment
3.1) removing the photosensitive power meter, and coaxially installing a collimating lens 12, a second half-wave plate 13, a second polarization beam splitter prism 14 and a thermosensitive power meter 15 in sequence at the outlet end of the kagome hollow photonic crystal fiber 7 from left to right, as shown in FIG. 3;
meanwhile, a monitoring unit 16 is arranged on a reflection light path of the second polarization splitting prism 14, and the spectrum change after coupling transmission is tested by using the reflection light of the second polarization splitting prism 14;
wherein, the collimating lens 12 adopts a lens with a long focus of 250mm to collimate the light beam;
3.2) adjusting the position of the second half-wave plate 13 to ensure that the transmission of the second polarization beam splitter prism 14 is maximum, and testing the output optical power of the second polarization beam splitter prism 14 in the transmission direction by adopting a wide-range thermosensitive power meter 15;
3.3) starting the monitoring unit 16, testing the spectral width and pulse width of the reflected light of the second polarization beam splitter prism 14, controlling the air pressure entering the air cavity inside the kagome hollow photonic crystal fiber 7 through a vacuum unit according to the tested spectral width and pulse width, further controlling the nonlinear effect of the ultrashort pulse in the kagome hollow photonic crystal fiber 7, actively controlling the air pressure according to the spectral change tested by the monitoring unit 16 to widen the spectrum, mainly based on the spectral widening generated by self-phase modulation, observing the spectral widening by controlling the air pressure to widen the originally injected spectrum from several nm to dozens of nm through the self-phase modulation, wherein the spectral width reaches dozens of nm to hundreds of nm, in the graph 4, the monitoring unit comprises a spectrometer and an autocorrelator, the spectrometer tests the spectral change (broadening change), and the autocorrelator tests the change of the pulse width, the change of the pulse width is mainly reflected in that the original relatively wide pulse is compressed into a shorter pulse, such as a pulse of dozens of femtoseconds, and finally, the nonlinear broadening of the spectrum and the compression of the pulse width are achieved. Typically, the relationship between the change in spectral width and barometric pressure is: the larger the air pressure is, the stronger the nonlinearity is in the process of ultrashort pulse transmission, the more obvious the self-phase modulation is generated, and the more obvious the spectrum broadening is. Meanwhile, the peak power of the injected laser pulse is related, and the higher the peak power is, the stronger the nonlinearity is under the same air pressure, and the more obvious the spectrum broadening is. Therefore, the method and the device adopt the peak power condition of the injected pulse and spectrum monitoring to modulate the air pressure to obtain the self-phase modulation spectrum broadening from dozens of nm to nearly 100nm, and further achieve nonlinear compression by combining dispersion compensation to obtain narrow pulse output.
The light source has the repetition frequency of 600kHz, the central wavelength of 1029nm, the spectrum width of about 10nm, the maximum output power of 20W, approximately collimated output light, the pulse width of 260fs and the diameter of a light spot of about 3 mm. The coupling efficiency is between 65% and 83% as shown in fig. 5 by the measured coupling efficiency curve. The spectrum produces obvious broadening, and the shortest output pulse width reaches 45 fs. As can be seen from FIG. 6, the input pulse spectrum at the beginning is only about 10nm, and the spectrum has obvious nonlinear broadening through transmission in the kagome hollow photonic crystal fiber of the embodiment, and the obtained output spectral width reaches nearly 50 nm. FIG. 7 is a graph of the original injection autocorrelation, pulse width 260 fs; fig. 8 shows the self-compressed pulse output obtained after transmission, with pulse width 45fs, by using nonlinear spectral broadening to introduce positive chirp and fiber negative dispersion to compensate each other after nonlinear transmission. The pulse self-compression system of the embodiment realizes high-efficiency coupling of space light to the Kagome hollow optical fiber by adopting a single-lens coupling mode, simultaneously realizes nonlinear self-compression of high-energy ultrashort pulses by parameter selection and air pressure control of the Kagome hollow photonic crystal fiber, realizes the original input pulse width of 260fs and the ultrashort pulse flexible optical fiber output with the narrowest output pulse width of 45fs, has the advantages of simple structure and low cost, does not need a dispersion device to perform extra dispersion compensation, and can directly realize coupling output of the ultrashort pulses of dozens of femtoseconds.
The above description is only for the purpose of describing the preferred embodiments of the present invention and does not limit the technical solutions of the present invention, and any known modifications made by those skilled in the art based on the main technical concepts of the present invention fall within the technical scope of the present invention.
Claims (8)
1. A pulse self-compression system based on Kagome hollow photonic crystal fiber is characterized in that: defining the emergent direction of a femtosecond laser light source (1) from left to right, wherein the system comprises a vacuum unit, a near-infrared high-reflection mirror pair, an attenuator, a focusing lens (6) and a kagome hollow photonic crystal fiber (7) with a protective outer layer, which are sequentially arranged from left to right;
the near-infrared high-reflection mirror pair is used for adjusting the femtosecond laser in the left-right direction and the height direction;
the attenuator comprises a first half-wave plate (4) and a first polarization beam splitter prism (5) which are coaxially arranged from left to right in sequence and are used for performing power attenuation on femtosecond laser;
the focusing lens (6) is used for adjusting the divergence angle and the spot size of the femtosecond laser beam, so that the beam focused by the focusing lens (6) is positioned at the end face of the inlet end of the kagome hollow photonic crystal fiber (7);
the inlet end and the outlet end of the kagome hollow photonic crystal fiber (7) are respectively sealed by a first hollow fiber sealing head (10) and a second hollow fiber sealing head (11), and the inner cavity of the first hollow fiber sealing head (10) and the inner cavity of the second hollow fiber sealing head (11) are communicated with the inner air cavity of the kagome hollow photonic crystal fiber (7);
the sealing window sheet (101) of the first hollow optical fiber sealing head (10), the sealing window sheet (101) of the second hollow optical fiber sealing head (11), the focusing lens (6) and the first polarization splitting prism (5) are coaxially arranged;
the first hollow optical fiber sealing head (10) is arranged on a five-dimensional adjusting frame and is used for translation of the inlet end of the kagome hollow photonic crystal fiber (7) in the vertical direction, the front-back direction and the left-right direction and adjustment of the height and the left-right angle, so that the position and angle of received incident light are adjusted;
the vacuum unit is used for adjusting the air pressure of an air cavity inside the kagome hollow photonic crystal fiber (7).
2. The Kagome hollow photonic crystal fiber based pulse self-compression system of claim 1, wherein: the near-infrared high-reflection mirror pair comprises a first reflecting mirror (2) and a second reflecting mirror (3) which are arranged in parallel; the included angle between the reflecting surface of the first reflecting mirror (2) and the optical axis of the femtosecond laser light source (1) is 45 degrees, and the included angle between the reflecting surface of the second reflecting mirror (3) and the optical axis of the first half-wave plate (4) is 45 degrees.
3. The Kagome hollow photonic crystal fiber-based pulse self-compression system of claim 1 or 2, wherein: the vacuum unit comprises a vacuum pump (8), a vacuum pipeline (17) and a vacuum controller (9);
one end of the vacuum pipeline (17) is communicated with the vacuum pump (8), and the other end of the vacuum pipeline is communicated with the inner cavity of the first hollow optical fiber sealing head (10) or the inner cavity of the second hollow optical fiber sealing head (11);
the vacuum controller (9) is arranged on the vacuum pipeline (17).
4. The Kagome hollow photonic crystal fiber based pulse self-compression system of claim 3, wherein: the first hollow optical fiber sealing head (10) comprises a pipeline (103), a vacuum shell (105), a gas sealing switch (107) and a gas inlet and outlet interface (106) which is used for being communicated with the vacuum pipeline (17);
the sealing window sheet (101) is arranged at one end of the pipeline (103) through an inlet flange (102); the other end of the pipeline (103) is arranged on the vacuum shell (105) through an outlet flange (104), and the inner cavity of the pipeline (103) is communicated with the inner cavity of the vacuum shell (105);
the gas inlet and outlet interface (106) is arranged on the outer wall of the vacuum shell (105) and is communicated with the inner cavity of the vacuum shell (105);
the gas sealing switch (107) is arranged on the gas inlet and outlet interface (106);
and the vacuum shell (105) is provided with an optical fiber interface for connecting the kagome hollow photonic crystal fiber (7).
5. The Kagome hollow photonic crystal fiber based pulse self-compression system of claim 4, wherein: the second hollow optical fiber sealing head (11) has the same structure as the first hollow optical fiber sealing head (10).
6. The Kagome hollow photonic crystal fiber based pulse self-compression system of claim 5, wherein: the first hollow optical fiber sealing head (10) further comprises a fixing plate (109);
the vacuum shell is arranged on the fixing plate (109);
the fixing plate (109) is mounted on the five-dimensional adjusting frame.
7. The Kagome hollow photonic crystal fiber based pulse self-compression system of claim 1, wherein: the kagome hollow photonic crystal fiber (7) has a core diameter of 57 mu m, a numerical aperture NA of 0.03 and a length of 5 m.
8. The coupling adjustment method of the Kagome hollow photonic crystal fiber-based pulse self-compression system of claim 1, comprising the following steps:
1) coarse adjustment of optical path
1.1) removing a focusing lens (6), and placing a CCD (charge coupled device) for detecting output laser at the outlet end of a kagome hollow photonic crystal fiber (7);
1.2) adjusting the light path direction of the incident laser by adopting a near-infrared high-reflection mirror until the light intensity measured by the CCD reaches the maximum;
2) fine adjustment of light path
2.1) installing a focusing lens (6), replacing the CCD with a photosensitive power meter, and ensuring that a focused light beam is positioned at the end face of the inlet end of the kagome hollow photonic crystal fiber (7) after installing the focusing lens (6);
2.2) adjusting the position of the inlet end of the kagome hollow photonic crystal fiber (7) by a five-dimensional adjusting frame until the output power value measured by the photosensitive power meter reaches the maximum value;
3) kagome hollow photonic crystal fiber (7) air pressure adjustment
3.1) removing a photosensitive power meter, and sequentially installing a collimating lens (12), a second half-wave plate (13), a second polarization beam splitter prism (14) and a thermosensitive power meter (15) at the outlet end of the kagome hollow photonic crystal fiber (7) from left to right;
meanwhile, a monitoring unit (16) is arranged on a reflection light path of the second polarization splitting prism (14), and the monitoring unit comprises a spectrometer and an autocorrelator;
3.2) adjusting the position of the second half-wave plate (13) until the transmission light power of the second polarization beam splitter prism (14) measured by a heat-sensitive power meter (15) reaches the maximum;
3.3) starting a monitoring unit (16), testing the spectral width and the pulse width of the reflected light of the second polarization beam splitter prism (14), and adjusting the air pressure of an air cavity inside the kagome hollow photonic crystal fiber (7) through a vacuum unit according to the tested spectral width and pulse width until the spectral broadening measured by a spectrometer reaches a set spectral width and the pulse measured by an autocorrelator reaches a set pulse width.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010712483.3A CN111969399B (en) | 2020-07-22 | 2020-07-22 | Pulse self-compression system based on Kagome hollow photonic crystal fiber and coupling adjustment method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010712483.3A CN111969399B (en) | 2020-07-22 | 2020-07-22 | Pulse self-compression system based on Kagome hollow photonic crystal fiber and coupling adjustment method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111969399A true CN111969399A (en) | 2020-11-20 |
| CN111969399B CN111969399B (en) | 2021-09-14 |
Family
ID=73362699
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010712483.3A Active CN111969399B (en) | 2020-07-22 | 2020-07-22 | Pulse self-compression system based on Kagome hollow photonic crystal fiber and coupling adjustment method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111969399B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113655566A (en) * | 2021-07-29 | 2021-11-16 | 中国科学院西安光学精密机械研究所 | Spatial light coupling method and coupling system for special photonic crystal fiber |
| CN114779411A (en) * | 2022-03-23 | 2022-07-22 | 武汉锐科光纤激光技术股份有限公司 | Laser transmission optical cable |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101494353A (en) * | 2009-02-27 | 2009-07-29 | 山东科技大学 | THz Laman fibre-optical laser |
| CN102147495A (en) * | 2011-03-18 | 2011-08-10 | 武汉邮电科学研究院 | Nonlinear fiber and ultrashort pulse generating device applying same |
| US20120082410A1 (en) * | 2010-09-30 | 2012-04-05 | Xiang Peng | Hybrid Waveguide Device in Powerful Laser Systems |
| CN104022431A (en) * | 2014-04-28 | 2014-09-03 | 中国科学院上海光学精密机械研究所 | Wide-bandwidth, high signal-to-noise ratio and ultrashort-laser pulse device |
| US20140334763A1 (en) * | 2013-05-08 | 2014-11-13 | Max-Planck-Gesellschaft zu Forderung der Wissenschaften e.V. | Method and light pulse source for generating soliton light pulses |
| CN104184042A (en) * | 2013-05-22 | 2014-12-03 | 中国计量学院 | Combined 1.9 mu m wavelength converter of hollow-core photonic crystal fiber and seal cavity |
| CN110537144A (en) * | 2017-01-09 | 2019-12-03 | 马克斯-普朗克科学促进协会 | Broad band light source device and the method for generating broadband optimal pulse |
-
2020
- 2020-07-22 CN CN202010712483.3A patent/CN111969399B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101494353A (en) * | 2009-02-27 | 2009-07-29 | 山东科技大学 | THz Laman fibre-optical laser |
| US20120082410A1 (en) * | 2010-09-30 | 2012-04-05 | Xiang Peng | Hybrid Waveguide Device in Powerful Laser Systems |
| CN102147495A (en) * | 2011-03-18 | 2011-08-10 | 武汉邮电科学研究院 | Nonlinear fiber and ultrashort pulse generating device applying same |
| US20140334763A1 (en) * | 2013-05-08 | 2014-11-13 | Max-Planck-Gesellschaft zu Forderung der Wissenschaften e.V. | Method and light pulse source for generating soliton light pulses |
| CN104184042A (en) * | 2013-05-22 | 2014-12-03 | 中国计量学院 | Combined 1.9 mu m wavelength converter of hollow-core photonic crystal fiber and seal cavity |
| CN104022431A (en) * | 2014-04-28 | 2014-09-03 | 中国科学院上海光学精密机械研究所 | Wide-bandwidth, high signal-to-noise ratio and ultrashort-laser pulse device |
| CN110537144A (en) * | 2017-01-09 | 2019-12-03 | 马克斯-普朗克科学促进协会 | Broad band light source device and the method for generating broadband optimal pulse |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113655566A (en) * | 2021-07-29 | 2021-11-16 | 中国科学院西安光学精密机械研究所 | Spatial light coupling method and coupling system for special photonic crystal fiber |
| CN114779411A (en) * | 2022-03-23 | 2022-07-22 | 武汉锐科光纤激光技术股份有限公司 | Laser transmission optical cable |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111969399B (en) | 2021-09-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111969399B (en) | Pulse self-compression system based on Kagome hollow photonic crystal fiber and coupling adjustment method thereof | |
| CN108563034B (en) | Reflective spatial filter debugging device and method | |
| CN114268009B (en) | Femtosecond pulse laser dual-wavelength expansion device and method and optical fiber laser thereof | |
| CN112688147B (en) | Pre-chirp management femtosecond laser pulse amplification device and system | |
| CN106469887B (en) | Double-pass amplifier of photonic crystal fiber | |
| CN110323663B (en) | Device and method for generating vector ultrashort laser pulse of intermediate infrared band | |
| EP2557641A1 (en) | Pulse fiber laser device | |
| CN111711059A (en) | High-efficiency femtosecond laser frequency doubling device based on combined lens and adjusting method thereof | |
| CN113745951A (en) | Laser device | |
| CN116526275A (en) | Ultra-short pulse generating device and method based on concave spherical lens and multi-pass cavity | |
| CN108490548B (en) | Integrated band-pass filter isolator | |
| CN113708203B (en) | Stable high-power ultrashort pulse generating system | |
| CN105301758A (en) | Picosecond mid-infrared pulse conversion device based on Fabry-Perot interferometer | |
| CN115084978A (en) | Multi-pass laser spectrum broadening optical system and method | |
| CN112636146B (en) | High-power mode-locked disc laser | |
| CN113341628A (en) | Femtosecond ultra-continuous white light generating device | |
| CN108039638B (en) | Low-threshold two-stage spectrum shaping flexible optical fiber high-power mode-locked laser | |
| CN117277031B (en) | Ultrafast laser nonlinear self-compression device and application thereof | |
| CN113675712B (en) | Deep ultraviolet ytterbium-doped fiber laser | |
| CN205303939U (en) | Compact stable high peak power optic fibre output laser instrument | |
| CN218005522U (en) | Hybrid high-power high-energy femtosecond chirped pulse amplification system | |
| CN115882322A (en) | Plano-concave multi-through-cavity nonlinear pulse compression system, method and application | |
| CN115764533B (en) | High-repetition-frequency high-energy femtosecond laser generation system and method | |
| CN217215491U (en) | High-repetition-frequency fiber green light femtosecond laser | |
| CN211981130U (en) | Laser device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |