Mid-infrared supercontinuum generation in a single-mode thulium-doped fiber amplifier

Abstract

Mid-infrared supercontinuum (SC) generation in a thulium fiber amplifier is reported. The system delivered an average output power of 2.37 W in a spectral band of ∼(1.75–2.7) μm which is, to the best of our knowledge, the highest average power of SC generated from a single-mode Tm-doped fiber. For wavelengths longer than 2.4 μm, the output power was as high as 0.49 W, constituting almost 21% of the total output power. A 10 dB spectral flatness in the wavelength interval ranging from 1.95 to 2.52 μm (570 nm span) with a corresponding (calculated) spectral power density greater than 3 mW nm−1 is demonstrated. Amplification in both emission bands of Tm3+ ions, as a way to effectively enhance SC generation towards longer wavelengths, is also discussed.

Thulium pumped mid-infrared 09–9μm supercontinuum generation in concatenated fluoride and chalcogenide glass fibers

“…Mid-IR SC sources have already been successfully applied in FTIR spectroscopy [15] and in hyperspectral imaging [16]. A further advantage of fiber based laser sources is that the average power can be scaled up by increasing the pump power [9,17], or by increasing the pump repetition rate [8,9], with the current record being a 10.5W average power ZBLAN SC demonstrated by Xia et al [9].…”

6.8 W all-fiber supercontinuum source at 1.9–2.5 μm

“…[11] of the excitation between several excited states at a high pump intensity resulting in lowering of the peak gain together with a spectral broadening of the amplification band (see figure 11 in [11]) as compared to the gain expected from 3 F 4 level only. Such a broad gain, originated from both the 3 H 4 and 3 F 4 excited states of Tm 3+ ions, would be obviously beneficial for the formation of SC.…”

“…Amplification of gain-switched and mode-locked Tm/Ho-doped laser pulses of a duration of a few microseconds in a Tm-doped amplifier resulted in 2.17 W output power [7]. Amplification of SC generated with a nanosecond Er-doped fiber laser in a Tm or Tm/Ho-doped fiber amplifier [8][9][10][11] resulted in up to 2.37 W of output power in the range of 1.95-2.52 μm at −10 dB level [11]. However, a much simpler system based on a master-oscillator-power amplifier (MOPA) configuration with only Tm-doped fibers has not been reported so far.…”

Mid-IR Ultrashort Pulsed Fiber-Based Lasers

“…SC generation in mid-infrared wavelengths range above 2 μm, and in particular in the transparency window of the atmosphere between 2 and 2.5 μm, is an important goal of applied fiber optics due to numerous applications such as LIDAR systems [31], optical coherence tomography [32], optical clocks, trace gas sensing [33] and environmental monitoring, as well as military technologies. So far, the SC generation in this wavelength range was demonstrated by various methods, e.g., pumping of a Ho-doped fiber amplifier with intense Q-switched pulses at 1.6 μm resulted in an output SC power of 0.4 W [27], by amplification of gain-switched and mode-locked Tm/Ho-doped laser pulses of a complex shape and duration on a few microseconds level in a Tm-doped amplifier resulted in 2.17 W [34], by amplification of already generated with nanosecond EDFL SC in Tm-doped fiber amplifier [35], [36] resulted in up to 2.37 W of output power in the range of 1.95-2.52 μm at -10 dB level [37]. Nevertheless, a much simpler system in a MOPA configuration utilizing a mode-locked laser seed thus ensuring the SC stability and quality and based on Tm-doped fibers only has not been yet reported and will be described in the following section.…”