Novel Picosecond Optical Pulse Sampling Technique for Measuring the Response of High-Speed Optical Modulators

Abstract

Efficient high-speed optical waveguide switches and amplitude modulators will be important components for utilizing the large available bandwidth of single-mode lightwave systems. In addition to amplitude modulation for digital coding, fast optical switches may prove very useful for high-speed time division multiplexing. Presently, several guided-wave optical switch/ modulators have been reported with demonstrated modulation bandwidth of approximately 1 GHz [1,2]. For high-speed operation, accurate switching speed measurements under electrical pulse operation are hampered by the finite speed of the pulsing circuit and the photodetector. Generally, it is necessary to estimate the actual device switching time by deconvolving the response time of the pulser and detector from the measured output pulse [1]. Undesirable optical damage effects generally preclude the high optical power levels required for fast photo- diodes or for nonlinear pulse correlation techniques [3]. We have developed a new measurement technique utilizing picosecond optical sampling pulses to overcome the limitation of finite detector speed.