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Reza Khazaeinezhad is currently a research fellow (Postdoc) at Wellman Center for Photomedicine at Harvard Medical School / Mass General Hospital in Boston in Dr. Ben Vakoc’s group. At Wellman center, he is developing new laser source for optical imaging instrumentation. He fabricated a novel high speed swept source laser based on stretched pulse Mode-locking technique. He has also done Zemax simulation and built a wide- and flat-field microscope. In addition, he designed and 3-D printed a handheld microscope based on a MEMS scanner which will be used for full-color and OCT imaging, simultaneously. Reza did his Ph.D. in the optical science and engineering program at Yonsei University in Seoul, South Korea in 2015. During his doctoral research, he worked on the development of Modelocked and Q-switched fiber lasers based on two-dimensional materials (MoS2 and WS2). He also did an experimental study on nonlinear properties of biomaterials (DNA) and investigated its applications in ultra-fast fiber laser. As a co-author he also worked on developing novel optical fiber sensor devices and hollow optical fiber based micro plasma jet.
We developed a novel high-speed and robust wavelength-swept laser source with long sweeping range and linear k-sampling for optical frequency domain imaging applications. In our configuration the wavelength tuning is achieved by using 8-m-long chirped fiber brag grating (CFBG) as a pulse compressor and stretcher. An intra-cavity fixed Fabry Perot etalon enforces the wavelength-stepped operation with 80 GHz separation between the wavelengths to ensure the long range imaging depth. Our total cavity length is 50 m with sweeping rate of 8 MHz and 84 nm bandwidth at 1560 nm center wavelength. Coherence length was measured to be over 50 mm with 0.02 nm instantaneous laser linewidth. The sweeping frequency was perfectly linear with high level of stability and repeatability. The tuning range of the laser can be easily increased by utilizing longer length of CFBG. This approach proposes the feasibility of CFBG to build a compact and practical wavelength-stepped laser source with high stability and cost effectiveness