Dispersion-Engineered Step-Index Tellurite Fibers for Mid-Infrared Coherent Supercontinuum Generation from 1.5 to 4.5 μm with Sub-Nanojoule Femtosecond Pump Pulses

Abstract

Featured Application: Supercontinuum generation in novel infrared fibers from high-repetition-rate femtosecond mode-locked laser pulses provides mid-infrared radiation with very attractive features such as high coherence and spectral power density over an ultra-broad spectral range, thus opening new prospects for remote sensing applications, in particular through mid-infrared spectroscopy.Abstract: Mid-infrared supercontinuum generation from 1.5 to 4.5 µm with sub-nanojoule femtosecond pump pulses is demonstrated by using a short segment of dispersion-engineered step-index tellurite fiber with very low OH content. Distinct group-velocity dispersion regimes in a simple design of step-index tellurite fiber are also reported, which allows to choose the nonlinear pulse propagation regime according to the required tailoring of the supercontinuum source. Numerical simulations based on the generalized nonlinear Schrödinger equation are used to determine optimized fiber parameters before experimental demonstrations. We also analyse the coherence properties of the resulting supercontinuum sources.

Highly coherent supercontinuum generation in a tellurite all-solid hybrid microstructured fiber pumped at 2 μm

“…In order to utilize more common laser sources such as fiber lasers around 1.5 or 2 μm, and to obtain a highly coherent SC, SCG in tellurite stepindex fibers, chalcogenide microstructured fibers, and chalcogenide photonic crystal fibers were demonstrated in the AND regime. [25][26][27][28][29][30] In those studies, chromatic dispersions were controlled to obtain small normal dispersion values at the pump wavelengths. However, the chromatic dispersion profiles were still bell-shaped with rapid change of dispersion around the pump wavelengths.…”

“…Such a property limits spectral broadening and the reported output SC bandwidths were narrow. [25][26][27][28][29][30] One obvious strategy to improve the spectral broadening by AND regime pumping is to flatten the chromatic dispersion over a wide wavelength range. Such chromatic dispersion promotes efficient SPM which is the main driving phenomenon for spectral broadening in the AND regime.…”

Mid-infrared supercontinuum generation with high spectral flatness in dispersion flattened tellurite all-solid hybrid microstructured optical fibers

“…As a result, the pulse intensity would decrease rapidly and the SC bandwidth would be narrow. 20,24,26) To benefit the high pulse intensity for efficient SPM as the pulse propagates along the optical fiber, one strategy is to flatten the fiber chromatic dispersion over a wide wavelength range. Some air-holes MOFs have been optimized for flattened chromatic dispersion.…”

“…SCG with silica PCFs, silicate PCFs, tellurite step-index fibers, tellurite tapered fiber, chalcogenide MOFs, and chalcogenide PCFs have been demonstrated by pumping around 1.5 and 2 μm in the AND regime. [19][20][21][22][23][24][25][26][27][28] Stepniewski et al pumped N-F2 all-solid PCF at 1360 nm and obtained an SC from 950-1850 nm at −20 dB level. 20) Al-Kadry et al pumped chalcogenide microwires at 1550 nm and obtained an SC from 1400-1900 nm at −20 dB level.…”

Highly Nonlinear Multimode Tellurite Fibers: From Glass Synthesis to Practical Applications in Multiphoton Imaging

“…In this perspective, heavy metal‐oxide glasses, including tellurite glasses, show interesting optical properties, for instance, high nonlinear indices (around 4.10 −19 m 2 W −1 , which appears to be 18 times higher than for silica), and mid‐infrared transparency (from visible to ≈6.5 μm). These properties [ 9,10 ] allow tellurite fibers to represent an attractive alternative for SC generation [ 11 ] and mid‐infrared laser sources.…”