An all-fibre robust and tunable Raman fibre laser with reconfigurable asymmetric cavities

Abstract

A robust Raman fibre laser (RFL) for tunable and multiple outputs has been proposed using an all-fibre asymmetric cavity which is composed of a wideband chirped fibre Bragg grating (CFBG) and narrowband tunable fibre Bragg gratings (TFBGs). The wideband CFBG has high reflectivity across the spectral range from 1404 to 1465 nm as an input reflector. Output couplers (OCs) consist of three TFBGs with center wavelengths of 1410, 1425 and 1440 nm, respectively, which can each be tuned over 10 nm. The output power and wavelength can be flexibly controlled by tuning of TFBGs in the 14xx nm band.

The Role of Rayleigh Backscattering of Coherent Light in the Mode Dynamics of Random DFB Fiber Lasers

“…In [14], a tunable optical band-pass filter (TOBPF) was introduced in the conventional random DFB fiber laser setup, with Raman gain, and tunable emission was experimentally observed in the range 1535-1570 nm. The tuning range is similar to those obtained in traditional Raman fiber lasers [117][118][119]. However, the tunable random DFB fiber laser showed a far better power flatness throughout the tuning range, not exceeding 3%, while traditional Raman fiber lasers are typically 20% flat in nearly the same tuning range [14].…”

Characterization of variable reflectivity of a polarization-maintaining fiber Sagnac mirror for long-distance remote fiber Bragg gratings cavity sensors

“…In the schematic of the proposed FBG sensor system (linear cavity using a tunable PMF Sagnac mirror), the SOA has a 3 dB optical bandwidth of 80 nm from 1480 to 1560 nm. Compared with the erbium-doped fiber amplification (EDFA) scheme, the SOA or fiber Raman amplifier shows better performance for simultaneous multi-wavelength lasing, due to the inhomogeneous gain broadening effect [12][13][14]. The 50% optical signal in the cavity is coupled out through the 50:50 fiber coupler and the remaining 50% optical signal propagates through the lasing cavity in order to produce an effective optical signal.…”

Multiwavelength Raman Fiber Lasers Using Hi-Bi Photonic Crystal Fiber Loop Mirrors Combined With Random Cavities

“…This difference in refractive indexes leads to a phase difference between the waves propagating in the Hi-Bi PCF (1) where is the length of the fiber and the wavelength of operation. The transmission spectrum of the Hi-Bi FLM is approximately a periodic function of the wavelength (2) where and are the angles between light in the propagation axis at the end of the Hi-Bi PCF. The wavelength spacing between two consecutive interference channels in the transmission spectrum is given by (3) From (3), it can be seen that the wavelength spacing between two consecutive channels in a FLM is inversely proportional to the birefringence and length of the fiber.…”

“…A dual wavelength Raman laser, 200 km long, utilizing two different-wavelength fiber Bragg gratings with a "random" Rayleigh scattering mirror was experimentally demonstrated [1]. Some other approaches were made in order to obtain multiple tunable outputs, being by using an all-fiber asymmetric cavity composed by wideband chirped fiber Bragg grating and narrowband tunable fiber Bragg gratings to obtain robust Raman fiber laser [2]; or by using a novel free-spectral-range tunable comb filter based on a superimposed chirped fiber Bragg grating and a linear cavity formed by a bandwidth-tunable chirped fiber Bragg grating reflector for continuously tunable spacing multiwavelength lasing [3]. Other approaches were based in tunable and stable lasing through power distribution among different lasing channels by adjusting the pump powers [4], or by using a tunable dual section high birefringence fiber Sagnac loop filter [5].…”