Power scaling of Raman fiber amplifier based on the optimization of temporal and spectral characteristics

Abstract

We comprehensively study the effects of temporal and spectral optimization on single-mode Raman fiber amplifiers. Amplified spontaneous emission sources and ytterbium-doped fiber lasers are employed as seed or pump lasers for comparison, and passive fibers are utilized as gain media. The influences of various parameters of the laser on 2nd order Raman threshold and maximum output power are investigated experimentally, including bandwidth, seed power, wavelength separation between pump and seed laser, and temporal stability. With the 190 m passive fiber, the output power increases from 99.5 W to 142.4 W, corresponding to 43.1% improvement through the optimization of seed laser power, pump wavelength and temporal performance of pump source in this amplifier, which has guidance on the establishment of high-power single-mode Raman fiber amplifiers.

Cladding-pumped Raman fiber laser with 0.78% quantum defect enabled by phosphorus-doped fiber

“…A home-made amplified spontaneous emission (ASE) source is used as the pump, with a wavelength tuning range of 1050-1080 nm and 3-dB bandwidth of 1.7 nm [49] . The usage of ASE as the pump source instead of the classical fiber-cavity-based oscillator has the advantages of low coherence and high temporal stability, which could reduce the intensity noise and improve the laser performances [50][51][52] . A fiber circulator with core diameter of 20 µm is mounted after the ASE source, to protect the pump from the potential backward laser and to monitor the backward light from the following oscillator.…”

Kilowatt Raman Fiber Laser Directly Pumped by Spectrally-Combined Diodes

“…Initially, the beam quality M 2 is improved to 5.8 (the pump~ 35) with Stokes power of 273W, while the output beam quality factor M 2 deteriorates to 7 when Stokes power up to 1082 W. However, due to the linear increase in Stokes beam power, the value of BE is gradually improved from 7.7 to 11.3. In the above process, as more multi-wavelength pumps are launched to the fiber, the power density in the fiber core increases gradually, the quantum defect leads to the generation and accumulation of massive waste heat in the fiber core, especially with the power scaling beyond kilowatt level [21][22][23][24][25][26]. The temperature of the fiber core increases rapidly that could result in a series of nonlinear effects on fiber system, such as the thermal lens effect and additional noise which eventually leads to the degradation of the output beam quality.…”

“…These advantages are of great significance for solving the aforementioned problems of the active fiber scheme [19,20]. In recent years, based on either oscillator or amplifier structure, remarkable achievements have been witnessed in RFLs pumped by YDFLs typically, whose output power has reached up to multiple kilowatts at 1120nm [21][22][23] and 1130nm [24][25][26]. It proves the feasibility of Raman gain to generate high-power laser.…”

Design of ultra-long-distance optical transport networks based on high-order remotely pumped amplifier

“…Distributed Raman amplification (DRA) and ROPA are very beneficial technologies to enlarge the transmission distance in long-haul WDM transmission systems thanks to their excellent low noise characteristics [2,[6][7][8][10][11][12][13][14][15]. Especially, an optimized combination of a DRA and a ROPA, was recently proposed to demonstrate an enhancement of optical signal to noise ratio (OSNR) and a long-distance terrestrial field-trial [7,8].…”