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US 4,448,479 AGranted
Traveling wave, electrooptic devices with effective velocity matching
AssigneeBell Telephone Laboratories, Incorporated
InventorRodney C. Alferness
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Abstract
A simulated velocity match between a traveling optical wave and a traveling electrical modulating wave is obtained in traveling wave, velocity mismatched electrooptic devices by introducing, at longitudinally spaced intervals along the electrical signal wavepath, means for producing the equivalent of a 180 degree phase shift in the effect of the modulating signal upon the operative electrooptic parameter of said device. This technique is employed to minimize the effect of walk-off due to velocity mismatch in modulators, phase shifter and mode converters.
Claims10
An optical device comprising:
- optical waveguiding means;
- electrical waveguiding means extending longitudinally along said optical waveguiding means over an interaction distance L for locally modulating, via the electrooptic effect, the operative parameter of said device;
- said electrical waveguiding means having a total length substantially equal to L, and including, at longitudinally spaced interval therealong, means for producing the equivalent of a 180 degree phase shift in said operative parameter, said 180 degree phase shifts occurring at intervals spaced apart a distance, l.sub.0, given by ##EQU15## where .lambda..sub.rf, V.sub.rf, n.sub.rf are, respectively, the wavelength, velocity of propagation, and refractive index at a specified electrical wave frequency;
- and V.sub.0 is the velocity of propagation at the frequency of the optical signal of interest.
1 more element
Dependencies are inferred from the claim text.