3μm Q-switched/Mode-locked Er³⁺-ZBLAN Fiber Lasers And High Power Mid-infrared Supercontinuum Laser Sources

3μm pulsed mid-IR fiber laser and high power mid-IR supercontinuum (SC) sources beyond3μm are of great intreasts for their various practical and potential applications. We have achieved passively Q-switched and mode-locked2.8μm Er3+-ZBLAN fiber laser based on Fe2+-ZnSe crystal and graphene, respectively. High power broadband laser sources in the mid-IR wavelength range based on dispertion-shifted tellurite fiber and chalcogenide photonics crystal fiber (PCF) when pumped by3μm short pulses have also been studied numerically.The major elements and results of this dissertation are as follows:1. A diode-pumped high concentration single-mode Er+-doped ZBLAN fiber laser passively Q-switched by a Fe2+-ZnSe crystal was demonstrated. With the maximum available pump power of2.8W,2.8μm mid-IR pulses with pulse duration of370ns, pulse energy of2.0μJ, average output power of300mW, corresponding to a peak power of5.34W, were achieved at a repetition rate of161kHz. A graphene deposited fiber dichroic mirror was made by the method of optically driven deposition and served as a saturable absorber. A diode-pumped passively Q switched2.78μm Er3+-doped ZBLAN fiber laser based on this graphene saturable absorber was achieved. Stable Q-switched operation with pulse duration of2.9μs and pulse energy up to1.67μJ at a repetition rate of37kHz was achieved.2. An Er3+-doped ZBLAN fiber laser was passively mode-locked by inserting a Fe2+-ZnSe crystal into the free space part of the cavity. Continuous-wave mode-locked pulses at2.8μm with an average power of51mW and pulse duration of19ps estimated from the spectral bandwidth were generated when a collimated beam traversed the Fe2+-ZnSe crystal.3. High power mid-IR SC laser sources based on W-type dispersion engineered tellurite and chalcogenide photonics crystal fibers (PCFs) pumped by3μm ultrafast lasers were proposed and numerically investigated. Simulation results indicated that when pumping a W-type tellurite fiber with a zero dispersion wavelength of2.7μm with2.78μm short pulses, an over40%power proportion of the SC laser beyond3μm could be obtained. Compared to the existing microstructured tellurite fibers, the achievable output power of this W-type solid-cladding tellurite fiber could be one order of magnitude higher. Morever, when As2Se3chalcogenide PCF is pumped with a2.78μm ultrafast laser, a super-broadband SC source covering two atmospheric windows and molecules’"fingerprint" region can be attained.