ABSTRACT
This chapter presents the fundamentals of time-wavelength signal processing by a comprehensive analysis of its important applications, the ultra-wideband time-stretched analog-to-digital conversion. It begins with a fundamental-physics analysis of the time-wavelength transformation including both continuous-time and discrete-time implementations and the implication of time-dilation on the signal-to-noise ratio. Digital signal processing (DSP) has revolutionized modern communication and radar systems by offering unprecedented performance and adaptivity. The application of DSP is hindered by the difficulty in capturing the wideband signal. Possible implementations include an array waveguide grating (AWG) in the loopback configuration or fiber Bragg grating (FBGs). Compared to continuous time-stretch, in the electro-optic modulator, the electrical signal is sampled by a multiwavelength pulse train. The discrete time-stretch implemented using FBGs has the similar latency as the implementation using AWGs. The chapter develops a comprehensive mathematical model for the time-stretch systems. The model is capable of predicting fundamental and higher order phenomena that modify the electrical signal during the time-stretch process.
