Chung Hsien Chen

US Patent:

50408658, Aug 20, 1991

Filed:

Apr 20, 1990

Appl. No.:

7/512287

Inventors:

Chung Y. Chen - Rancho Palos Verdes CA
Irwin L. Newberg - Northridge CA

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

G02B 610
G02F 200

US Classification:

350 9614

Abstract:

In a Mach-Zehnder electro-optic modulator (10), an optical waveguide (14) includes two branches (20,22) extending between an optical input (16) and an optical output (18) is formed in a substrate (12) of a material having electro-optical properties. An electrical signal applied to a modulation input (34) affects the material such that the effective optical lengths of the branches (20,22) vary differently in correspondence with the magnitude of the electrical signal. The optical signals propagating through the branches (20,22) interfere with each other at the optical output (18) at a phase angle depending on the difference between the effective optical lengths. A selected electrical bias voltage applied to the modulation input (34) causes non-linear modulation of an input optical signal with one or more even integral multiples of an electrical input signal which is additionally applied to the modulation input (34), thereby providing frequency multiplication. Two or more non-linearly operated modulators (50) may be connected in cascade to increase the multiplication ratio, with a photodetection (80) converting the optical output of one modulator to an electrical signal which is applied to the modulation input of the next modulator. One linearly operated modulator (100) may be connected in cascade with a non-linearly operated modulator to modulate a frequency multiplied carrier with a data signal.