Study On Fourier-domain Mode-locking Swept Source At 1.3?M

Optical coherence tomography(OCT)is a new type of non-invasive,non-invasive,high-resolution optical scanning technology that can perform in-vivo imaging of various biological tissues.With the development of time,the current OCT technology can perform real-time two-dimensional or even three-dimensional imaging of the patient's tissue.Therefore,in recent years,a large range of applications have been achieved in the field of medical imaging.Swept Source OCT(SS-OCT)is a kind of Fourier domain OCT(FD-OCT).Its biggest feature is the use of swept laser and point detection the way.The sweep laser is one of the core components of the Swept Source OCT system.The parameters of the sweep laser determine the upper limit of the technical index that the OCT system can reach.In order to get better performance of sweep laser,this paper built two kinds of 1.3?m sweep laser with different tuned filters for research.1.Build a 1.3?m band short-cavity sweep laser based on grating/ Polygon scanner filter.A grating/ Polygon scanner filter adopt a Littrow structure.The tuning filter can reach 132 nm sweept range.After that,two 1.3?m short-cavity sweep laser with different structures were built.The output power are 6 mW and 0.184 mW,the sweep ranges are 110 nm and 50 nm,and the sweep frequency speeds are 45 kHz and 36 kHz.A new sweep lase structure was designed using the four-wave mixing effect of light,which can increase the output power of the light source to 9.9mW and the scanning range to about 120 nm.At this time,the sweep frequency of the swept laser is 45 kHz.2.Using Fourier domain mode-locking technology,two 1.3?m-band FDML sweep laser based on grating / Polygon scanner filter were built.One is a conventional ring cavity structure,the length of the cavity is 4km,and the laser power is 9.9mW,the sweep range is 128 nm and the sweep speed is 51 kHz.The other is to use the four-wave mixing effect of light,the length of the cavity is 6 km.and the light travels in the opposite direction in the optical delay line,which is caused by the nonlinear effect of light.The sweep frequency range of the generated laser is widened,and the sweep range rises to 130 nm.However,the power of the laser decreases to 8 mW and the sweep speed of the generated laser decreases to 34 kHz due to the longer cavity length and greater light loss.3.Build two 1.3?m band FDML swept laser based on Fabry-Perot tuned filter.The length of the resonant cavity is 9.4km and 4km respectively,and the sweep frequency is 42 kHz and 100 kHz respectively.Their frequency range is 80 nm and 26 nm respectively.