CN210957263U - Device for generating Q-switched mode-locked noise square wave pulse - Google Patents
Device for generating Q-switched mode-locked noise square wave pulse Download PDFInfo
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- CN210957263U CN210957263U CN201821261168.8U CN201821261168U CN210957263U CN 210957263 U CN210957263 U CN 210957263U CN 201821261168 U CN201821261168 U CN 201821261168U CN 210957263 U CN210957263 U CN 210957263U
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Abstract
The utility model discloses a device for producing transfer Q mode locking class noise square wave pulse, include: the pump light source, wavelength division multiplexer, erbium-doped optical fiber, it is first, second polarization controller, the relevant isolator of polarization, fiber coupler, single mode fiber, the output of pump light source is connected with wavelength division multiplexer's first input, wavelength division multiplexer's output is connected with first polarization controller's input through erbium-doped optical fiber, first polarization controller's output is connected with fiber coupler's input through the relevant isolator of polarization, fiber coupler's first output is connected with second polarization controller's input through single mode fiber, second polarization controller's output is connected with wavelength division multiplexer's second input. The Q-switched mode-locked noise square wave pulse is generated by utilizing the combined action of the nonlinear polarization rotation effect and the high nonlinear effect of the long single-mode optical fiber. The device can be applied to the fields of supercontinuum generation, micro-structure processing, medical treatment and the like.
Description
Technical Field
The invention relates to the technical field of optics, in particular to a laser emitting device.
Background
The passive mode-locking fiber laser has the advantages of good beam quality, small volume, simple structure, low cost and the like, and has important application value in the fields of optical communication, optical fiber sensing, material processing, biomedical treatment and the like. In general, conventional mode-locked ultrashort pulses with gaussian or hyperbolic secant shapes can be obtained in passively mode-locked fiber lasers, but noise-like pulses can also be obtained by reasonably adjusting laser cavity structures and parameters such as dispersion, loss, gain, and nonlinearity. The noise-like pulse is a special mode locking state in a passive mode locking fiber laser, and the typical characteristics of the noise-like pulse are as follows: 1) the pulse shape measuring method is characterized in that a wide wave packet is arranged in a time domain, and a fine structure formed by a plurality of picosecond and femtosecond pulses with randomly evolved intensities and widths is arranged in the wave packet, so that when an oscilloscope measures the shape of the noise-like pulse, only a single square wave pulse can be seen due to the bandwidth limitation of the oscilloscope, and when the pulse width of the noise-like pulse is measured by autocorrelation, a very wide base is seen, and a coherent peak is arranged in the middle; 2) the spectrum is smooth, no Kelly sideband and steep edge exist, and the width of the spectrum is wide and even exceeds the gain bandwidth of the gain fiber; 3) with low temporal coherence. Based on the characteristics, the noise-like pulse has important application in the fields of supercontinuum generation, low-optical coherence tomography, low-coherence spectrum interferometer and the like.
On the other hand, the laser can be divided into four operation states of continuous wave operation (CW), Q-switched operation (Q-switching), continuous wave mode-locking (CW mode-locking), and Q-switched mode-locking (Q-switching mode-locking) according to the time characteristic, as shown in fig. 1. The Q-switching mode locking has the characteristics of two operation states of Q-switching and mode locking. Under the operation of Q-switching mode locking, the period of Q-switching giant pulse is generally in the order of mu s, the repetition frequency is close to the relaxation oscillation frequency, and the interior of the Q-switching giant pulse is a short pulse with the pulse width in the order of picosecond. Because the Q-switched mode locking can generate short pulse output with high peak power, the Q-switched mode locking device has wide application in the aspects of nonlinear frequency conversion, microstructure processing, medical treatment and the like.
The Q-switched mode-locked pulse can be obtained by using a separate Q-switching device and mode-locking device in the laser cavity, but can also be obtained by one device or a system with Q-switched mode-locking function (such as a nonlinear polarization rotating cavity, a nonlinear amplification ring cavity and a nonlinear optical ring cavity). However, most of the existing devices for generating the Q-switched mode-locked pulse can only realize that the inside of a Q-switched envelope is the traditional ultrashort pulse, and can not realize the output of the Q-switched mode-locked noise pulse.
SUMMERY OF THE UTILITY MODEL
The utility model aims at: an all-fiber laser is built by adopting an all-fiber device, and the Q-switched mode-locked noise square-wave pulse output is realized by utilizing the combined action of the nonlinear polarization rotation technology and the high nonlinear effect of the long single-mode fiber, so that the technical problem that the Q-switched mode-locked noise pulse cannot be output in the prior art is solved.
The utility model provides a solution of its technical problem is: an apparatus for generating a Q-switched mode-locked noise-like square wave pulse, comprising: the output end of the pump light source is connected with the first input end of the wavelength division multiplexer, the output end of the wavelength division multiplexer is connected with the input end of the second polarization controller through the single-mode fiber, the output end of the second polarization controller is connected with the second input end of the wavelength division multiplexer, and the second output end of the optical fiber coupler is used for outputting the light wave of the Q-switching mode-locking noise square wave pulse.
Further, the length value of the erbium-doped fiber is 4m, the working wavelength range of the erbium-doped fiber is 1565nm-1625nm, and the length of the single-mode fiber is 250 m.
Further, the optical power output ratio of the second output end to the first output end of the optical fiber coupler is 10: 90.
the utility model has the advantages that: the utility model utilizes the long single-mode optical fiber of 250m to generate high nonlinear effect to assist the nonlinear polarization rotation technology to realize the output of Q-switched mode-locked noise square wave pulse; a nonlinear polarization rotation effect is generated in the cavity based on a polarization-dependent isolator and an optical fiber birefringence effect to realize a Q-switched mode-locked state, and a 250m single-mode optical fiber is used for generating a noise-like mode-locked square wave in the cavity in an auxiliary manner; 4m erbium-doped fiber is used, so that the gain in the cavity is improved, and the high nonlinear effect in the cavity is enhanced; a 10% energy output coupler is used, most energy of the pulse is left in the resonant cavity, and the nonlinear effect is enhanced; the use of full-optical fiber devices is convenient for welding, and the equipment is simple and reliable.
Drawings
In order to more clearly illustrate the technical solution in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below. It is clear that the described figures represent only some embodiments of the invention, not all embodiments, and that a person skilled in the art can also derive other designs and figures from these figures without inventive effort.
FIG. 1 is a schematic diagram of four states of operation of a laser;
fig. 2 is a schematic structural diagram of the inventive device.
Detailed Description
The conception, the specific structure, and the technical effects produced by the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings to fully understand the objects, the features, and the effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and other embodiments obtained by those skilled in the art without inventive labor based on the embodiments of the present invention all belong to the protection scope of the present invention. In addition, all the coupling/connection relationships mentioned herein do not mean that the components are directly connected, but mean that a better coupling structure can be formed by adding or reducing coupling accessories according to specific implementation conditions. All technical characteristics in the invention can be interactively combined on the premise of not conflicting with each other.
when the device works, the pumping light source 1 adopts a semiconductor laser with the highest power of 460mW and the central wavelength of 980nm, the erbium-doped optical fiber 3 with the length of 4m and the working wavelength range of 1565nm-1625nm is used as an optical gain medium, meanwhile, a section of 250m single-mode optical fiber 7 is used as a medium for improving the intracavity nonlinear effect, the polarization-related isolator 5, the erbium-doped optical fiber 3 and the single-mode optical fiber 7 are used for generating the nonlinear polarization rotation effect to realize the output of L-band laser, and the mode-locked fundamental frequency of the whole device is 778.21 kHz. The polarization-dependent isolator 5 can ensure unidirectional laser operation in the laser cavity and has a polarization selection effect on the laser. The first and second polarization controllers 4, 8 may be used to adjust the polarization state of the laser light. The optical fiber coupler 6 is used for laser output, and the output power of the second output end of the optical fiber coupler 6 is 10%. After the coupling output, the optical spectrum analyzer and the high-speed oscilloscope can capture the optical wave output by the second output port of the optical fiber coupler 6 to obtain the noise-like square wave pulse in the Q-switched mode-locked state.
While the preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that the invention is not limited to the details of the embodiments shown, but is capable of various modifications and changes without departing from the spirit of the invention.
Claims (2)
1. An apparatus for generating a Q-switched mode-locked noise-like square wave pulse, comprising: the output end of the pump light source is connected with the first input end of the wavelength division multiplexer, the output end of the wavelength division multiplexer is connected with the input end of the first polarization controller through the erbium-doped optical fiber, the output end of the first polarization controller is connected with the input end of the optical fiber coupler through the polarization-related isolator, the first output end of the optical fiber coupler is connected with the input end of the second polarization controller through the single-mode optical fiber, the output end of the second polarization controller is connected with the second input end of the wavelength division multiplexer, and the second output end of the optical fiber coupler is used for outputting the light wave of the Q-switching mode-locking noise square wave pulse;
the length value of the erbium-doped fiber is 4m, the working wavelength range of the erbium-doped fiber is 1565nm-1625nm, and the length of the single-mode fiber is 250 m.
2. The apparatus of claim 1, wherein the means for generating a Q-switched mode-locked noise-like square wave pulse comprises: the optical power output ratio of the second output end to the first output end of the optical fiber coupler is 10: 90.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108847570A (en) * | 2018-08-06 | 2018-11-20 | 佛山科学技术学院 | It is a kind of for generating the device of Q-switch and mode-locking noise like square-wave pulse |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108847570A (en) * | 2018-08-06 | 2018-11-20 | 佛山科学技术学院 | It is a kind of for generating the device of Q-switch and mode-locking noise like square-wave pulse |
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