Deborah A Robinson

US Patent:

53473922, Sep 13, 1994

Filed:

Feb 26, 1992

Appl. No.:

7/842300

Inventors:

Chien-Chung Chen - San Gabariel CA
Deborah L. Robinson - Scotts Valley CA
Hamid Hemmati - Encino CA

Assignee:

The United States of America as represented by the Administrator of the
National Aeronautics and Space Administration - Washington DC

International Classification:

G03H 102
G08B 523
H01S 310

US Classification:

359279

Abstract:

An electro-optic resonant cavity is used to achieve phase modulation with lower driving voltages. Laser damage thresholds are inherently higher than with previously used integrated optics due to the utilization of bulk optics. Phase modulation is achieved at higher speeds with lower driving voltages than previously obtained with non-resonant electro-optic phase modulators. The instant scheme uses a data locking dither approach as opposed to the conventional sinusoidal locking schemes. In accordance with a disclosed embodiment, a resonant cavity modulator has been designed to operate at a data rate in excess of 100 Mbps. By carefully choosing the cavity finesse and its dimension, it is possible to control the pulse switching time to within 4 ns and to limit the required switching voltage to within 10 V. Experimentally, the resonant cavity can be maintained on resonance with respect to the input laser signal by monitoring the fluctuation of output intensity as the cavity is switched. This cavity locking scheme can be applied by using only the random data sequence, and without the need of additional dithering of the cavity.