CW LASER MODULATOR

RECENT DEVELOPMENTS IN OPTICAL COMMUNICATION TECHNOLOGY ARE VERY ENCOURAGING FOR THE POTENTIAL OPERATION OF OPTICAL SATELLITE CROSSLINKS. MOST NOTABLE IS THE DEVELOPMENT OF HIGH EFFICIENCY ND:YAG RING LASERS WHICH WOULD BE ATTRACTIVE TRANSMITTERS IF WIDE BANDWIDTH EXTERNAL PHASE MODULATORS COULD BE DEVELOPED. A TRAVELING-WAVE CONFIGURATION GIVES THE MAXIMUM BANDWIDTH FOR ELECTRO-OPTIC MODULATORS. THE MAXIMUM BANDWIDTH-LENGTH PRODUCT IS FIXED BY THE VELOCITY DIFFERENCE BETWEEN THE CO-PROPAGATING MICRO/MILLIMETER WAVE AND OPTICAL SIGNAL AND CAN BE DRAMATICALLY IMPROVED BY PROPAGATING THE MICROWAVE IN A LOW INDEX DIELECTRIC MATERIAL. FOR A GIVEN APPLIED VOLTAGE A FURTHER IMPROVEMENT CAN BE OBTAINED THROUGH THE USE OF BATIO(3) WHICH HAS AN ELECTRO-OPTIC COEFFICIENT 35 TIMES LARGER THAN LINV0(3). THIS COMBINATION OF MATERIALS CAN BE REALIZED BY FABRIATING A RIDGE WAVE GUIDE FROM A SINGLE CRYSTAL BATIO(3) THIN FILM GROWN ON A LATTICED MATCHED DIELECTRIC SUBSTRATE. THE OBJECTIVE OF THE PHASE I WORK IS TO DEMONSTRATE LOW LOSS OPTICAL TRANSMISSION IN RIDGE WAVEGUIDES FABRICATED FROM BATIO(3) THIN FILMS DEPOSITED ON LAGAO(3) BY MOCVD. THESE RESULTS WILL ESTABLISH THE BASIC MATERIALS TECHNOLOGY REQUIRED FOR THE FABRICATION OF PROTOTYPE BATIO(3) TRAVELING-WAVE PHASE MODULATOR IN PHASE II.