Performance Comparison of Broadband Optical Modulators for 40GSPS All-Optical ADC

Optical phase- (PM) and spatial-modulators (SLM) are of interest in integrated realization of highly stable RF clocks using self-forced opto-electronic oscillators and all-optical ADC that are to be realized using electro-optic (EO) chromophores on Si-Photonics platforms. Design and performance comparison of broadband RF electrodes of the optical modulators are presented in this paper using lateral coupled micro-strip (CMS) driving electrodes as travelling and standing waves. Improved bandwidth and group delay flatness are observed using proper terminations of CMS in PM. Optical waveguide structure of SLM designs is based on PM design with a higher index of refraction prism as optical superstrate to achieve leaky wave. Optical core waveguide design comparisons are made in terms of CPO-1 and JRD-1 EO chromophores with PMMI as host surrounded by NOA65 cladding. Optimized SLM is basis of 40GSPS ADC with effective number of bits as high as 9.4.