Optical Encoding and Decoding of Femtosecond Pulses in the Spectral Domain Using Optical Coupler with Fiber Gratings

Shin-ichi WAKABAYASHI  Hitomi MORIYA  Asako BABA  Yoshinori TAKEUCHI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E85-C   No.1   pp.135-140
Publication Date: 2002/01/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Ultrafast Optical Signal Processing and Its Application)
Category: OTDM Transmission System, Optical Regeneration and Coding
Keyword: 
fiber grating,  femtosecond pulse,  spectral separation,  directional coupler,  optical encoding,  

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Summary: 
We have developed optical encoding devices for processing femtosecond pulses. These devices are based on spectral separation devices and light modulators with fiber gratings. Experiments were made to encode a light pulse in the spectral domain. These experiments utilize the characteristics that a femtosecond light pulse has a very broad spectrum. An input femtosecond light pulse is decomposed into a series of wavelength components. Each wavelength component with narrow spectra <1 nm width is successfully extracted into a single mode fiber. Light modulators corresponding to wavelength components are assigned to the 1st bit, the 2nd bit, the 3rd bit, ・・・, the nth bit, respectively. All of the encoded wavelength components are again recombined into a single time-varying signal and transmitted through an optical fiber. Decoding at receiving site is made by the reverse operation. Encoding and decoding for 2-bit and 4-bit signals were demonstrated for 200 fs input light pulse with about 40 nm spectral width.