Supercontinuum Generation In Photonic Crystal Fiber Pumped By Pulsed ASE

In the applications such as optical coherence tomography(OCT),the light sources are required to have low time coherence,so that high imaging resolution can be achieved.Amplified spontaneous emission(ASE)sources are a kind of incoherent light source.On one side,the ASE sources can be used directly in some of these applications.On the other side,when they are used to pump nonlinear medium,the generated supercontinuum of low time coherence can be applied to more fields.This article is aimed to investigate the generation and amplification processes of a pulsed ASE source.The amplified ASE source is used to pump photonic crystal fiber to generate supercontinuum.The main contents of this project are listed as follows:Firstly,a nanosecond pulsed ASE source is obtained.A fiber loop mirror structure is introduced to promote the output power of the 1060 nm band.280 mW continuous ASE is achieved and is modulated by an acousto optic modulator and an electro optic modulator to generate the pulse with 8 ns width and 50 kHz repeated frequency.Secondly,the master oscillator power amplifier is used,and the average output power of the pulsed ASE source is amplified to 49 W.The peak power of the ASE source can be adjusted by controlling the temporal shape of the seed pulse.The nonlinear effects occurring in the fiber such as four wave mixing can be weaken in the ASE amplification case,so that higher peak power ASE is available.Thirdly,the amplified ASE source is used to pump photonic crystal fiber for supercontinuum generation,and visible supercontinuum of 35 W average power is obtained.Since most of studies on supercontinuum generation are based on lasers sources,the introduction of the ASE source can be helpful in researching the fundamental principles of supercontinuum generation.