High-peak-power single-oscillator actively Q-switched mode-locked Tm^3+-doped fiber laser and its application for high-average output power mid-IR supercontinuum generation in a ZBLAN fiber

Abstract

A single-oscillator actively Q-switched mode-locked (QML) thulium-doped silica fiber laser is presented and used to pump a ZrF₄-BaF₂-LaF₃-AlF₃-NaF (ZBLAN) fiber for mid-infrared (mid-IR) supercontinuum (SC) generation. The fiber laser provided high-peak-power levels directly from the oscillator delivering single mode-locked pulse energies up to 48 μJ, being 2-4 orders of magnitude higher than conventional continuous wave mode-locked lasers. By pumping a ZBLAN fiber specially designed for high-output-power SC generation, 7.8 W have been achieved in all spectral bands with a spectrum extending to 4.2 μm.

Watt-level and spectrally flat mid-infrared supercontinuum in fluoroindate fibers

“…High brightness broadband sources in mid-infrared (MIR) atmospheric transmission windows have attracted a significant scientific interest in the past decade due to their wide range of potential uses in various fields, such as spectroscopy, metrology, as well as defense applications [1][2][3]. Supercontinuum (SC) sources using fluorozirconate-based fibers have reached watt level powers [4][5][6][7][8][9], some of which extended up to 4.7 μm by using short ZBLAN fibers [10], but usually the SC extensions are restricted to wavelengths below ∼4.2 μm when using long ZBLAN fibers. A wavelength extension of the SC above 5 μm is possible when using fluoroindate glass fibers [11][12][13], allowing to completely cover the infrared atmospheric windows at 1.5-1.8 μm, 2.0-2.4 μm, and 3-5 μm for the aforementioned applications.…”

Broadband and top-flat mid-infrared supercontinuum generation with 3.52 W time-averaged power in a ZBLAN fiber directly pumped by a 2-µm mode-locked fiber laser and amplifier

“…When mid-IR spectral region is concerned, soft glass fibers, including tellurite [5,6], fluoride [1,[7][8][9][10][11][12] and chalcogenide [13,14] fibers can be adopted as nonlinear media. However, among all soft glass fibers, only heavy metal fluoride fibers, including fluorozirconate (ZBLAN) [15][16][17][18][19] and fluoroindate (InF 3 ) [20,21] are technologically mature to be used for multi Watt level SC generation.…”

“…Different types of pulsed thulium-doped fiber-based laser systems, such as mode-locked [18,19], Q-switched and mode-locked [8,23] as well as gain-switched and modelocked [24,25] providing femtosecond [7] and picosecond [23,25] pulses, have been already proposed to pump fluoride fibers. In particular, CW model-locked fiber lasers followed by a cascade of amplifiers delivering optical pulses with pulse widths in the picoseconds range allow scaling output SC power to over 10 W, while being relatively easy in realization.…”

Mid-infrared Supercontinuum Generation to ∼4.7 μm in a ZBLAN Fiber Pumped by an Optical Parametric Generator

“…Their main drawback is a low resistance to moisture, leading to a degradation in air with prolonged exposure. Supercontinuum generation in fluoride fibers pumped with femtosecond [13], [14], picosecond [15], [16], and nanosecond [7], [17] pulses has been reported during the last decade. An ultra-wide SC spectrum extending from ultraviolet to 6.28 μm [13], as well as an SC source emitting an average power as high as 24.3 W [18], generated out of ZBLAN fibers, have been demonstrated.…”