Frequency noise of a Bragg grating fibre laser

Linewidth and phase noise characteristics of DFB fibre lasers

“…That the extracted Lorentzian component of the linewidth might not be uniquely related to spontaneous emission should not be too unexpected. First, these Lorentzian linewidths are still orders of magnitude larger than that expected from the Schawlow-Townes spontaneous emission-induced values 6 . Secondly, while the white noise spectrum arising from spontaneous emission will yield a Lorentzian lineshape, the converse need not be strictly true.…”

“…This is perhaps surprising, considering that predictions of the intrinsic linewidths of fiber lasers based on the well-known Schawlow-Townes formula indicate linewidths of just 60 Hz or less 6 . A common suggestion as to why the observed linewidths remain far above their theoretical limit is that the increased noise is caused by environmental perturbations, such as external vibration and acoustic noise, which the fiber laser may be more susceptible to.…”

Frequency and Intensity Noise of Single Frequency Fiber Bragg Grating Lasers

“…Frequency noise densities that are believed to be dominated by spontaneous emission seeding (25) for f 3 kHz have been reported for a L c = 19 mm DBR single frequency fiber laser with relatively high cavity losses a rt M ∼ 0 05 [24].…”

A Stabilized Fiber Laser for High-Resolution Low-Frequency Strain Sensing

“…However, many sensing applications require sensitivity at lower frequencies. In the low-frequency regime, fiber laser frequency noise is significantly larger than at high frequencies [7], [8], thus limiting sensitivity below a few hundred Hz. In the case of a passive sensor system, where the sensor is remotely interrogated, active frequency stabilization can be used to improve the frequency noise of the laser.…”