OPTICAL AMPLIFIERS AND LIQUID-CRYSTAL SHUTTERS APPLIED TO ELECTRICALLY RECONFIGURABLE FIBER OPTIC SIGNAL PROCESSORS

Citation
B. Moslehi et al., OPTICAL AMPLIFIERS AND LIQUID-CRYSTAL SHUTTERS APPLIED TO ELECTRICALLY RECONFIGURABLE FIBER OPTIC SIGNAL PROCESSORS, Optical engineering, 32(5), 1993, pp. 974-981
Citations number
8
Categorie Soggetti
Optics
Journal title
ISSN journal
00913286
Volume
32
Issue
5
Year of publication
1993
Pages
974 - 981
Database
ISI
SICI code
0091-3286(1993)32:5<974:OAALSA>2.0.ZU;2-R
Abstract
We demonstrate the application of optical amplifiers and polymer-dispe rsed liquid-crystal (PDLC) shutters to electrically reconfigurable fib er optic delay line signal processors. Two 8-tap finite impulse respon se (FIR) fiber filter modules were fabricated. These two modules can a lso be interconnected in a cascaded or parallel configuration to imple ment a 16-tap fiber FIR filter. An erbium-doped fiber amplifier with a peak gain of about 20 dB was used to compensate for the large optical losses involved in the filters due to the large tap numbers. The rela tively inexpensive PDLCs were used to realize electrically reconfigura ble analog tap weights. The individual fiber filters were then evaluat ed for their impulse and frequency responses. The fabricated filters u sed single-mode fibers and fiber components and were polarization inde pendent to within 0.5 dB. The sampling frequency was about 200 MHz, wh ich can easily be upgraded into the gigahertz range. The tapping extin ction ratio was about 13 dB with subkilohertz tunability speed. The am plified spontaneous emission noise can limit the filtering performance unless appropriate spectral filtering is included before detection. T hese optically amplified electrically reconfigurable fiber signal proc essors have the potential to lead to the realization of complex progra mmable and adaptive optical systems.