Fiber Lasers

Fiber lasers have gained increasing popularity, thanks to their many unique properties such as monolithic architectures, compactness, high efficiency, and excellent heat dissipative capacity. Their multiform parameters, wavelength, pulse duration, average power, and pulse repetition rate, to name a few, make fiber lasers suitable for wide and varied applications. For micro-and nano-engineering applications, ultrafast picosecond and femtosecond (ps/fs) fiber lasers are frequently employed due to their “cold ablation” characteristic, instead of their continuous wave or Q-switched counterparts. This chapter is structured as follows: firstly, the status quo of fiber laser development will be summarized, and secondly, a brief introduction will be given on mode-locked fiber laser oscillators and high-power ultrafast fiber laser amplifiers based on chirped pulse amplification (CPA) technique, with single-crystal fibers included. A particular emphasis will be made on fiber laser sources used for high harmonic generation, which have repetition rates on the order of ~MHz, and those used for “cold” processing, which have repetition rates on the order of ~GHz-THz. A mention of radially polarized fiber lasers and flexible ultrafast laser delivery using hollow-core fibers will also be made, as well as a brief review of gas-filled hollow-core fiber and capillaries used to shorten pulse durations down to sub-100 fs or sub-10 fs.