Title :
Wave-coupled LiNbO/sub 3/ electrooptic modulator for microwave and millimeter-wave modulation
Author :
Bridges, William B. ; Sheehy, Finbar T. ; Schaffner, James H.
Author_Institution :
Div. of Eng. & Appl. Sci., California Inst. of Technol., Pasadena, CA, USA
Abstract :
A new technique of phase velocity matching in electrooptic modulators was demonstrated. The results show that the phase velocity mismatch due to material dispersion in traveling-wave LiNbO/sub 3/ optical waveguide modulators can be greatly reduced by breaking the modulation transmission line into short segments and connecting each segment to its own surface dipole antenna. The array of antennas is then illuminated by the modulation signal from below at the proper angle to produce a delay from antenna to antenna that matches the optical waveguide´s delay. A phase modulator 25 mm in length with five antennas and five transmission line segments was operated from 4.6 to 13 GHz with a maximum phase modulation sensitivity of over 100 degrees /W/sup 1/2/.<>
Keywords :
electro-optical devices; integrated optics; lithium compounds; optical modulation; optical waveguides; phase modulation; 25 nm; 4.6 to 13 GHz; LiNbO/sub 3/ electrooptic modulator; SHF; antenna delay; material dispersion; microwave modulation; millimeter-wave modulation; modulation signal; modulation transmission line; optical waveguide modulators; phase modulation sensitivity; phase modulator; phase velocity matching; phase velocity mismatch; surface dipole antenna; traveling-wave; wave-coupled modulators; waveguide delay; Dipole antennas; Electrooptic modulators; Optical arrays; Optical materials; Optical modulation; Optical sensors; Optical waveguides; Phase modulation; Propagation delay; Transmission line antennas;
Journal_Title :
Photonics Technology Letters, IEEE
