2–10 µm Mid‐Infrared Fiber‐Based Supercontinuum Laser Source: Experiment and Simulation

Abstract

Mid‐infrared supercontinuum (mid‐IR SC) sources in the 2–20 µm molecular fingerprint region are in high demand for a wide range of applications including optical coherence tomography, remote sensing, molecular spectroscopy, and hyperspectral imaging. Herein, mid‐IR SC generation is investigated in a cascaded silica‐ZBLAN‐chalcogenide fiber system directly pumped with a commercially available pulsed fiber laser operating in the telecommunications window at 1.55 µm. This fiber‐based system is shown to generate a flat broadband mid‐IR SC covering the entire range from 2 to 10 µm with several tens of mW of output power. This technique paves the way for low cost, practical, and robust broadband SC sources in the mid‐IR without the requirement of mid‐infrared pump sources or Thulium‐doped fiber amplifiers. A fully realistic numerical model used to simulate the nonlinear pulse propagation through the cascaded fiber system is also described and the numerical results are used to discuss the physical processes underlying the spectral broadening in the cascaded system. Finally, recommendations are provided for optimizing the current cascaded system based on the simulation results.

Mid-infrared supercontinuum generation in chalcogenide glass fibers: a brief review

“…Generally, fluoride fibers are always chosen as the firststage fiber in the cascading scheme because of the following excellent properties: 1) high damage threshold; 2) generating SC sources with > 3.5 μm long wavelength edge extending above the ZDW of typical step-index fluoride fibers around 1.5 μm; 3) high output power of up to 30 W [18]. Subsequently, this concept has been proved to be feasible by many experimental results [29,[76][77][78][79][80]. In [29], a MOPA pump laser with a repetition rate of 600 kHz shown in Fig.…”

Recent Advances in Supercontinuum Generation in Specialty Fiber

“…step-index fiber pumped by 150 fs pulses at 6 µm delivered by an OPA system [67]. Using an ultra-high numerical aperture chalcogenide step-index fiber, C. R. [69]. The experimental setup is shown in Fig.…”

“…The filtered SC was then injected into a 9m long chalocogenide fiber that generated 2-10 µm SC (see Fig. 3(c)) with an average output power of 16 mW [69]. This technique paves the way for low cost, practical, and robust broadband SC sources without the requirement of mid-IR pump sources or Thulium-doped fiber amplifiers.…”

“…The insets show the optical mode profiles out of both the ZBLAN (b) and chalcogenide (c) optical fibers. Taken from Ref [69]…”

Analysis and design of dispersion-engineered cascaded channel waveguide for mid-infrared supercontinuum generation employing pump source at telecommunication wavelength

“…Through step-wise extension toward the MIR due to progressively red-shifting of initial pulse in the cascade system is performed. The main key idea behind the extension of MIR SC through cascading dispersion-engineered highly nonlinear waveguides is that the propagated pulse strongly enhances the soliton self-frequency shift (SSFS) while it progressively propagated inside the cascaded waveguides [31].…”