We demonstrate a new class of all-fiber frequency comb filter that exhibits unprecedented capabilities for tuning the comb's free spectral range (FSR). The filter exploits a spectral Talbot-like effect in a sampled chirped fiber Bragg grating. The FSR is tailored by application of a linear strain gradient to modify the relative phase between the samples. The FSR can be tuned in discrete steps that correspond to the nominal value of the FSR of the sampled unchirped grating divided by integer factors. In this demonstration the FSR is varied from 51 to 3.9 GHz.
© 2005 Optical Society of America
(060.2330) Fiber optics and optical communications : Fiber optics communications
(070.6760) Fourier optics and signal processing : Talbot and self-imaging effects
(120.2440) Instrumentation, measurement, and metrology : Filters
(230.1480) Optical devices : Bragg reflectors
Julien Magné, Philippe Giaccari, Sophie LaRochelle, José Azaña, and Lawrence R. Chen, "All-fiber comb filter with tunable free spectral range," Opt. Lett. 30, 2062-2064 (2005)