The Research Of Erbium-doped All-Fiber Pulse Laser And Its Frequency-doubling Characteristics

Various applications have emerged with the rapid development of laser technology,and pulse fiber lasers have also made breakthrough progress.Nanosecond pulse fiber lasers have the advantages of simple structure,high peak power,and large single pulse energy,etc.,in laser processing and biological detection.,military defense,laser radar and other fields have important applications;femtosecond pulsed fiber lasers can be used in ultra-fast time-resolved spectroscopy,bio-two-photon imaging and other fields because of their wide-spectrum light source with high coherence.Here,we will focus on laser radar applications and biological two-photon imaging applications.We will use erbium-doped fiber lasers as the core,nanosecond pulsed fiber lasers,femtosecond Erbium-doped fiber chirped pulse amplification systems,and femtosecond pulsed erbium doping.The fiber laser frequency doubled red laser launched a comprehensive system research.First,we proposed a fully polarizationmaintaining double-clad erbium-ytterbium co-doped fiber laser based on an “8” cavity,which achieved a high single-pulse energy,noise-like nanosecond pulse output;then,it successfully used chirped pulse amplification technology.An all-fiber femtosecond pulsed ytterbium-doped fiber laser was developed and used as a fundamental-frequency photomultiplier to achieve a femtosecond red laser output.The main research content of this article is as follows:1.Research on nanosecond pulsed-ytterbium co-doped all-fiber lasers.First,the traditional way to obtain nanosecond pulses is introduced,and then nanosecond noise pulses are introduced.By comparing several methods of generating noise-like pulses,based on the considerations of integration,stability,etc.,the selection based on "8" The word cavity way.A stable,self-energizing,fully polarization-maintaining double-clad erbium-ytterbium co-doped fiber laser based on a nonlinear optical ring mirror was experimentally investigated,and a high energy nanosecond noise pulse was successfully generated.In order to compare the pulse parameters,two different cavity lengths(~210 meters and ~510 meters)were set.The energy of the single pulse obtained in the long cavity is as high as 1.54 ?J,which is the highest value of the single-pulse energy that is directly generated by the fiber laser at present,which is an order of magnitude higher than that reported previously.In addition,the center wavelengths at 1616 nm and 1612.3 nm obtained by us can completely cover the absorption line of ethane gas and can be used for the detection of ethane gas.We also conducted numerical simulations of the generation of noise-like pulses.The numerical simulation data of the noise-like pulse(time domain envelope,spectrum,autocorrelation trajectory)is in good agreement with the experimental results.2.Research on femtosecond Erbium-doped fiber germanium pulse amplification system.According to the main components of the CPA system,an experimental study of an all-fiber oscillator based on a passive mode-locking technique is first performed,followed by a study of an erbium-doped fiber amplifier and a main oscillation power amplification technique,and finally,a study of a pulse compressor.Through experiments,we obtained a ytterbium-doped fiber oscillator with a pulse width of 220 fs and an average output power of 1.3mW as the seed source.The dispersion compensation fiber was used as a stretcher to widen the pulse to 80 ps,and then passed through the two-stage core amplification and the first-level cladding.After the amplification,a pulsed laser with an average output power of 1.6 W was obtained.Finally,the pulse was compressed using a grating pair.Finally,a pulse output of 400 fs was obtained,and the average output power was 0.96 W.3.Study the femtosecond pulsed Erbium-doped fiber laser frequency multiplication.Firstly,starting from the coupling wave equation,the theory of frequency multiplication is deduced,and it is pointed out that the phase matching conditions must first be satisfied in the frequency multiplication process.Secondly,the frequency-doubling crystal selection and the characteristics of the BIBO crystal are introduced.Again,the nonlinear optical simulation software SNLO,The frequency multiplication design scheme was simulated.Finally,the double-frequency red laser output of the femtosecond pulsed Erbium-doped fiber laser is realized by using the BIBO crystal angle phase matching technique and the out-of-cavity frequency multiplication scheme.When the maximum average output power of the baseband light is 960 mW,a red laser output with a maximum output power of 40 mW is realized with a corresponding conversion efficiency of 5.56%.At the maximum power,the center wavelength of the red laser is measured at 785 nm,3dB spectrum.Line width is 3nm...