Solitonic supercontinuum of femtosecond mid-IR pulses in W-type index tellurite fibers with two zero dispersion wavelengths

Abstract

We present a detailed experimental parameter study on mid-IR supercontinuum generation in W-type index tellurite fibers, which reveals how the core diameter, pump wavelength, fiber length, and pump power dramatically influence the spectral broadening. As pump source, we use femtosecond mid-IR pulses from a post-amplified optical parametric oscillator tunable between 1.7 μm and 4.1 μm at 43 MHz repetition rate. We are able to generate red-shifted dispersive waves up to a wavelength of 5.1 μm by pumping a tellurite fiber in the anomalous dispersion regime between its two zero dispersion wavelengths. Distinctive soliton dynamics can be identified as the main broadening mechanism resulting in a maximum spectral width of over 2000 nm with output powers of up to 160 mW. We experimentally demonstrated that efficient spectral broadening with considerably improved power proportion in the important first atmospheric transmission window between 3 and 5 μm can be achieved in robust W-type tellurite fibers pumped at long wavelengths by ultra-fast lasers.

Tellurite Glass and Its Application in Lasers

“…The W-type index profile makes it possible to tailor the ZDW, and this fiber can be fusion spliced to robust step-index silica fiber with relative ease. In 2016 Kedenburg et al studied SC generation spanning 2.6-4.6 μm in low-loss W-type index tellurite fiber with a length of 15 cm [84]. Additionally, they studied the variation of spectral bandwidth with core diameter, pump wavelength, length of fibers, and pump power.…”

Design of W-Type Index Chalcogenide Fiber for Highly Coherent Mid-IR Supercontinuum Generation

“…This effect can be present when the mode field radius and the operating wavelength become too large. Hence, an effective cutoff wavelength λf exists and occurs at a V-parameter [10] of around 1.4. From the above two conditions, the operating wavelength must be between λf and the single-mode cutoff wavelength (λc), that is, λc < λ < λf.…”

“…The advantages of such a double-clad fiber are a tight confinement mode, a flattened dispersion profile, more flexibility to control the locations of the ZDWs than in that SIF, and a higher possible V-parameter (V = 3.8) as compared to (2.405) at SIF. This large value of the V-parameter enables the enlargement of the core diameters whilst maintaining the single mode operation, resulting in lower coupling losses [10]. Also, this fiber type can be fusion spliced to standard SIF therefore it is suitable for an all-fiber system.…”

“…Also, this fiber type can be fusion spliced to standard SIF therefore it is suitable for an all-fiber system. The investigation of tellurite W-type index structure has been already considered for Mid-IR SC (2-5 µm) [10][11][12]. However, this type of fiber remains unexplored for chalcogenide based Mid-IR SC.…”

Design of Highly Coherence MIR Supercontinuum Generation in W-type Index Chalcogenide Fiber

“…One approach to control the chromatic dispersion is by applying W-type index fiber. The investigation of tellurite W-type index structure has been already done for MIR SC (2-5 µm) [3]. However, this type of fiber has not been yet applied for chalcogenide based MIR SC.…”