Raman amplification

A Raman fiber amplifier, works similar to a normal optical amplifier, but based on the non linear Raman effect. The energy of the injected pumping light is transmitted through a certain length of fiber on a likewise coupled into the signal light ( Stokes, anti-Stokes ). The pump frequency interacts with many molecules, this raises an energetically higher energy levels and thus generates compared to the previous state inversion. By the effect of the stimulated emission of radiation of the frequency of the first Stokes line is enhanced, which thus receives similar benefits as the pump light. Glass fibers or crystals as the active medium can be used, resulting in a frequency offset Raman 10-15 THz forming and thus the output light has a longer wavelength about 60 nm has ( at 1000 nm).

Is generated in a fiber Raman amplifier by the process of stimulated emission, Raman frequency-shifted light, allows the relationship between the pump power Pp, and the signal power Ps described by a differential equation system.

To construct a Raman fiber laser, frequency-selective Bragg grating written into the fiber from the respective pump wavelength, reflecting, for example, the fundamental wavelength and the respective generated by the Raman - Stokes orders resonant effect. Between these levels, the power of the pump light coupled by the wave signal. In this way, cascaded Raman laser can be constructed by the resulting first - order Stokes pumping a second Stokes order, and so on. Raman fiber laser can be pumped up or down as the regular fiber laser, depending on which point is coupled to the pump light. They offer a very good solution to provide frequency-selective light output over a very wide wavelength range.

• Laser beam source
• Solid State Physics
• Fiber optics