In-amplifier and cascaded mid-infrared supercontinuum sources with low noise through gain-induced soliton spectral alignment

Abstract

The pulse-to-pulse relative intensity noise (RIN) of near-infrared (near-IR) in-amplifier supercontinuum (SC) sources and mid-IR cascaded SC sources was experimentally and numerically investigated and shown to have significantly lowered noise due to the fundamental effect of gain-induced soliton-spectral alignment. The mid-IR SC source is based on a near-IR in-amplifier SC pumping a cascade of thulium-doped and ZBLAN fibers. We demonstrate that the active thulium-doped fiber not only extend the spectrum, but also to significantly reduce the RIN by up to 22% in the long wavelength region above 2 μm. Using numerical simulations, we demonstrate that the noise reduction is the result of an interplay between absorption-emission processes and nonlinear soliton dynamics leading to the soliton-spectral alignment. In the same way we show that the RIN of the near-IR in-amplifier SC source is already significantly reduced because the spectral broadening takes place in an active fiber that also introduces soliton-spectral alignment. We further show that the low noise properties are transferred to the subsequent fluoride SC, which has a RIN lower than 10% (5%) in a broad region from 1.1–3.6 μm (1.4–3.0 μm). The demonstrated low noise significantly improves the applicability of these broadband sources for mid-IR imaging and spectroscopy.

Fourier Transform Spectroscopy Using Novel Mid-infrared Supercontinuum Sources

“…However, compared to thermal sources, the SC sources demonstrate a high relative intensity noise (RIN) due to noise amplification in the nonlinear broadening process. By increasing the repetition rate and utilizing shorter pulse duration, the RIN of the state-of-the-art mid-infrared SC sources has been notably decreased compared to the earlier demonstrations [2]. Within the framework of the H2020 project FLAIR (Flying ultrAbroadband single-shot InfraRed sensor), we developed a home-built, compact, and transportable FTS, using only offthe-shelf optical components, especially developed to work with ultra-broadband mid-infrared SC sources for multispecies trace gas detection.…”

Real-time high-resolution mid-infrared optical coherence tomography

“…σ 2 ex scales with the mean power squared. It depends on the pulse repetition rate and the pulse-to-pulse relative intensity noise (RIN) of the SC source determined by the nonlinear dynamics of the SC generation process [10]. As our SC source is using long pump pulses, the SC generation is based on modulational instability amplifying quantum noise and is thus inherently noisy [11].…”

Delocalized SPM rogue waves in normal dispersion cascaded supercontinuum generation

“…The input to the As 2 Se 3 fiber is the output of the ZBLAN fiber, which is obtained by propagating noise seeded Gaussian shaped 40ps pulses from a directly modulated 1560nm seed diode through a 5m long Erdoped silica fiber amplifier (EDFA), followed by a 1.5m long Tm-doped fiber amplifier (TDFA), similar to the one described in [26], and finally the 7m long ZBLAN fiber. During amplification in the EDFA, the input pulse undergoes MI and breaks up into a number of solitons to generate an in-amplifier SC [31,32], resulting in an SC with a spectral edge around 2.3µm and 800mW of average power at 1MHz repetition rate. In the TDFA the spectral edge is extended to 2.8µm before being coupled into the 7m ZBLAN fiber to generate the ensemble averaged output spectrum shown in the top of Fig.…”