Distortion Reduction Filters for Radio-on-Fiber System

Noritaka TAGUCHI
Tsuneto KIMURA
Yasunori ATSUMI

IEICE TRANSACTIONS on Electronics   Vol.E90-C    No.2    pp.365-372
Publication Date: 2007/02/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.2.365
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Evolution of Microwave and Millimeter-Wave Photonics Technology)
distortion,  filter,  IM3 components,  radio-on-fiber system,  semiconductor lasers,  

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Three distortion reduction filters for radio-on-fiber systems are proposed and evaluated from the standpoint of improvements in in-band third order intermodulation (IM3) components (spurious components), insertion loss, temperature stability and so on. The basic filter configuration includes optical comb filter, RF (radiowave frequency) comb filter, and RF dual band rejection filter (DBRF). Experiments are conducted at 2 GHz band for frequency separation Δf=5 MHz and 100 MHz in the temperature range of -10 to +50. These filters can reduce IM3 components even in the saturation region, unlike conventional linearizers. An optical comb filter can reduce IM3 components more than 20 dB and noise level around 10 dB if its polarization controller is properly adjusted, but its insertion loss is large and stability against vibration is very poor. The proposed RF comb filter and RF-DBRF can reduce IM3 components by more than 20 dB and noise level by more than 3 dB. Their stability against vibration and temperature change is good, and insertion losses are 1-2 dB for Δf=100 MHz.