Nonlinear Fiber Optics

NFX aims at research and development of advanced products utilizing nonlinear effects in optical fibers. The invention of the laser in 1960s gave birth to a new field of optics, called nonlinear optics because the material response could no longer be taken to be linear when an intense electromagnetic field is present. Following the fast development of the low-loss optical fibers, a new branch of nonlinear optics, nonlinear fiber optics, has been active since 1970s. Since optical fibers can maintain high optical intensities over long lengths, the efficiency of the nonlinear processes is much enhanced that makes optical fibers a good candidate for the observation and utilization of a wide variety of nonlinear effects at a relatively low power levels. Many nonlinear phenomena have already found great applications in optical fiber communications, fiber lasers, fiber sensors, etc. 

For example, Raman scattering, scattering of light from optical phonons, can transfer a fraction of power from one optical field to another field, whose frequency is downshifted by an amount determined by the vibration modes of the molecular medium. Brillouin scattering, scattering of light from acoustic phonons, can generate new optical waves whose frequency difference compared to that of the incident wave is determined by the nonlinear medium. Both of these two effects in optical fibers can be used to make fiber amplifiers, fiber lasers, and distributed fiber sensors for temperature and strain measurement. In contrary to Raman and Brillouin scattering, Rayleigh scattering which introduces no frequency shift, is scattering of light from non-propagating fluctuations of the material. It already has found many applications, such as optical time-domain reflectometry, intrusion sensors, and distributed acoustic sensors. NFX has been developing systems utilizing these effects for a variety of products ranging from lasers, test equipment, to sensing systems.