A Tapered Fiber Q-switched Fiber Laser Based On Black Phosphorus Saturable Absorbe

Today,the development of laser technology is changing with each passing day.Since the invention of the laser in the second half of the 20 th century,after decades of development,it has changed from the very beginning to the present.Nowadays,lasers can no longer be used only for research and experimentation,but they have moved towards life.They have performed well in microscopic exploration,micro-processing,biomedicine,and national defense military.They have finally benefited humanity and promoted society.improvement.Fiber lasers,which are an important part of lasers,have been thriving because of their obvious advantages.In this paper,the study of ytterbium-doped fiber lasers with black phosphorus as saturable absorbers was conducted,and non-linear polarization evolution(NPE)mode-locked ytterbium-doped and erbium-doped fiber lasers were studied,and then the mode-locked laser synchronization experiment is carried out.Research is mainly divided into the following three parts:1.The ytterbium-doped fiber Q-switch experiment with black phosphorus as the saturable absorber was performed.The black phosphorus was prepared by the liquid phase exfoliation method.At the same time,a new structure was introduced in the resonant cavity—a tapered fiber,the diameter is usually only a few micrometers.The evanescent field under this condition is very powerful.Therefore,the quality of the taper fiber is directly related to whether the experiment can proceed smoothly.Before the experiment,the fusion taper was used to prepare the taper fiber.After many failures and attempts,the parameters were successfully obtained.A good tapered fiber,and using it as an experiment,got a good Q-switched result: the repetition frequency was 101.3k Hz,and when the pump power was165 m W,the shortest pulse width was 1.09?s.The largest single-pulse energy is 114.72 n J,and a dual-wavelength Q-switching phenomenon occurs at wavelengths of 1030.72 nm and1034.42 nm.2.The design and construction experiment of a small ytterbium-doped oscillator based on the NPE mode-locking principle was performed.The small oscillator designed is small and exquisite,suitable for acting as a seed source for the entire amplification system,and can be used as a product after the housing is added.By rotating the wave plate,the small oscillator outputs a stable mode-locked pulse train with good stability and can last for one week.The output laser has a pulse width of 3 ps,a spectral width of 31 nm,and a neat and stable waveform on the oscilloscope.The repetitive frequency is 39.98 MHz and the average output power is 17.5 m W.Oscillators of this parameter can be used as seed sources for ytterbium-doped fiber laser amplifiers,and their performance in both spectral and mode-locked stability is excellent.3.Two ytterbium-doped fiber oscillators based on the NPE mode-locking principle and one erbium-doped fiber oscillator were built.Both of them achieved the output of mode-locked pulses,and they were used to perform dual-ytterbium oscillator synchronization experiments and ytterbium-doped / erbium-doped oscillator synchronization experiments,also built a cross-correlation measurement of the optical path.In the erbium doped/erbium-doped oscillator synchronization experiments,stable synchronization results were obtained,and the synchronization duration was more than 72 hours.When the synchronization is achieved,the pump power of the ytterbium-doped oscillator is 250 m W,the output power from the polarization beam splitter(PBS)is 55.1m W,and the pump power of the Erbium-doped oscillator is 300 m W,and the output power from the PBS is5.9m W,which is relatively lower.