title: 220 μJ monolithic single-frequency Q-switched fiber laser at 2 μm by using highly Tm-doped germanate fibers.
abstract: We report a unique all fiber-based single-frequency Q-switched laser in a monolithic master oscillator power amplifier configuration at ~1920 nm by using highly Tm-doped germanate fibers for the first time. The actively Q-switched fiber laser seed was achieved by using a piezo to press the fiber in the fiber Bragg grating cavity and modulate the fiber birefringence, enabling Q-switching with pulse width and repetition rate tunability. A single-mode polarization maintaining large core 25 μm highly Tm-doped germanate fiber was used in the power amplifier stage. For 80 ns pulses with 20 kHz repetition rate, we achieved 220 μJ pulse energy, which corresponds to a peak power of 2.75 kW with transform-limited linewidth.
authors.affiliation: NP Photonics Inc., Tucson, Arizona 85747, USA. wshi@npphotonics.com
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.forename: Eliot B
authors.initials: EB
authors.lastname: Petersen
authors.forename: Dan T
authors.initials: DT
authors.lastname: Nguyen
authors.forename: Zhidong
authors.initials: Z
authors.lastname: Yao
authors.forename: Arturo
authors.initials: A
authors.lastname: Chavez-Pirson
authors.forename: N
authors.initials: N
authors.lastname: Peyghambarian
authors.forename: Jirong
authors.initials: J
authors.lastname: Yu