High performance laser linewidth broadening for stimulated Brillouin suppression with zero parasitic amplitude modulation

Abstract

To enable optimum network transmission, the ideal is to launch as high laser power as possible into the optical fiber, to overcome the effects of fiber attenuation and maintain an acceptable signal to noise ratio. Launching high powers into a fiber however, results in unwanted nonlinear effects. Stimulated Brillouin scattering (SBS) is one of the nonlinear effects which reflects a significant proportion of the transmitted optical power back to the transmitter, degrading the system severely. This paper reports the development of a digitally selected supermode distributed Bragg reflector monolithic laser chip which can provide significant linewidth broadening using a pure frequency modulation technique by application of a dither current. By modifying a small segment of the laser chip material refractive index, it produces a modulation of the longitudinal mode and hence laser frequency; the monolithic laser chip has reduced the effects of SBS significantly with very little parasitic amplitude modulation.

Performance improvement of power-over-fiber system using noise-modulated laser diode

“…However, when the input optical power exceeds a certain threshold, the rise in output optical power slows down; meanwhile, the backscattered optical power increases sharply. This "certain threshold" is usually called the SBS threshold, defined as an input optical power when the backscattering optical power is 0.4% of the forward launched power [21]. Thus, the SBS thresholds in Figs.…”

Experimental study of SBS suppression and coherence property of 1064nm high power multi-tone fiber amplifier

“…The amount of light backscattered depends on the length of the fiber and the laser power launched. The SBS effect is small when the fiber is short and increases with fiber length [2]. Satisfying certain phase matched conditions, once the injected laser power exceeds a certain point, the backscattered laser power will grow dramatically with increased injected laser power.…”

Experimental study of SBS suppression with phase-modulation in all-fiber amplifier

“…The backscattered Stokes light is shifted to lower optical frequency (and longer wavelength) by the Brillouin-shift frequency. The degree of the shift depends on fiber materials [4] . The long interaction length and the high power densities lead to relatively low threshold power for the onset of SBS, which severely limits the power of the laser light transmitting through a fiber.…”