Sub-watt threshold, kilohertz-linewidth Raman distributed-feedback fiber laser

Abstract

We report a low-threshold, narrow linewidth Raman distributed-feedback (R-DFB) fiber laser at 1109.54 nm based on a 30 cm long center π phase-shifted Bragg grating written directly in a commercially available germano-silica (Ge/Si) fiber. The R-DFB was pumped by a continuous-wave (CW) linearly polarized fiber source at 1064 nm, and the threshold power, full width at half-maximum (FWHM) linewidth and slope efficiency with respect to the incident pump power are measured to be 440 mW, <2.5 kHz (measured with a 29.75 km fiber delay line) and 13.5%, respectively. An rf spectrum analyzer confirms that the R-DFB fiber laser exhibits single-frequency performance.

Detailed study of four-wave mixing in Raman DFB fiber lasers

“…It can be seen that the FWM conversion efficiency grows and peaks as the κ increases up to ~39 m -1 . This we believe is due to the shorter effective cavity length of the DFB cavity for a stronger κ [17]. On the other hand, for a constant κ, the FWM conversion efficiency is bigger for a smaller phase mismatch factor, δk, which can also be seen in Fig.…”

“…1. It consists of a high power continuous-wave (CW), linearly polarized pump source at ~1064 nm for the initial R-DFB fiber laser generation [17] and a linearly polarized TLS (DL pro, Toptica Photonics, 1040 -1080 nm) as the probe wave for FWM generation in the R-DFB fiber laser. The TLS was amplified by a polarization maintaining (PM) Yb-doped fiber amplifier (YDFA).…”

Ultrawide-range four-wave mixing in Raman distributed-feedback fiber lasers

“…This principle was previously reported in the context of semiconductor DFB lasers [3,5]. However, so far, no FWM-related wavelength conversion has been observed in DFB fiber lasers.Recently, Raman DFB (R-DFB) fiber lasers with subwatt level threshold and high output power have been experimentally demonstrated [6,7]. In that particular design, the phase-shifted DFB grating forms a high reflectivity resonating cavity for the laser signal, while being mostly transparent to wavelengths outside the bandgap of the DFB grating.…”

“…Recently, Raman DFB (R-DFB) fiber lasers with subwatt level threshold and high output power have been experimentally demonstrated [6,7]. In that particular design, the phase-shifted DFB grating forms a high reflectivity resonating cavity for the laser signal, while being mostly transparent to wavelengths outside the bandgap of the DFB grating.…”

Ultra-Broadband Wavelength Conversion Based on Four-Wave Mixing in a Raman DFB Fiber Laser

“…1(a). A high power continuous-wave (CW) linearly polarized pump source at ~1064 nm was used as the pump source for generating the R-DFB signal [7] and a TLS (DL pro, Toptica Photonics) was employed as the probe for FWM generation and was amplified by a PM Yb-doped fiber amplifier (YDFA). The outputs of the lasers were respectively connected to isolator1 (ISO1) and ISO2 and then polarization controller1 (PC1) and PC2.…”