The field of fiber lasers and fiber optic devices has experienced a sustained rapid growth despite witnessing the infamous 'telecom bubble burst'. All-fiber optic devices have inherent advantages of relatively low cost, compact design, light weight, low maintenance, and increased vibration tolerances. In this research, a novel fiber laser and several fiber optic devices for applications in sensing and medical imaging have been proposed, demonstrated, and analyzed.; Differential absorption lidars (DIALs) are used to monitor trace gases and require two synchronized narrow linewidth laser sources of nearly the same wavelength. Sophisticated airborne lidar systems may benefit from the fiber laser technology because it could provide a rugged, efficient and lightweigth narrow-linewidth laser source. Our research in this direction resulted in a tunable Dual-wavelength Q-switched fiber laser seed-source for possible applications in DIAL. The fiber laser is based on Sagnac loop filters and has a stable output. The novelty of the dual-wavelength fiber laser is that only one laser is needed to generate perfectly synchronized two-wavelength pulses.; The fiber laser was also used to demonstrate a high-resolution fiber optic confocal Doppler velocimeter. The narrow spectral linewidth of the fiber laser (≤ 10 kHz), which is an order of magnitude narrower than the commonly used semiconductor diode lasers or He-Ne lasers, could provide a much longer working distances. We demonstrated a confocal Doppler velocimeter, capable of providing ultrahigh spatial resolution (∼ 5mum) for high-precision velocity distribution measurement applications.; Optical coherence tomography (OCT) is an emerging non-invasive optical imaging technique that can be used to perform high-resolution cross-sectional in vivo imaging of biological tissues. In the final part of this research, we demonstrate a fully integrated all-fiber common-path optical coherence tomography (OCT) system. The unique common-path interferometer based approach offers the advantages of compact and simplified instrumentation due to ease of all single mode fiber (SMF) implementation, circumvention of the polarization and dispersion mismatch issues, and increase in the vibration tolerance of the system. This technology is especially promising for Endoscopic OCT imaging, as it could counter the issue of 'downlead sensitivity' (polarization fadings caused by polarization distortions due to bending of the endoscope arm). A thorough analysis on optimization of system sensitivity is also presented. Systematic experiments were conducted to confirm some of our signal to noise ratio (SNR) analysis and were found to be in excellent agreement with the theory presented. Several novel fiber optic probes were built and investigated to optimize the system and enable more flexibility in order to cover a wider range of applications.
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