Leaky waveguide deflector for 40 GS/s and 6 bits all-optical analog-to-digital converters

Abstract

Analog-to-digital converters (ADC) are an important part of realizing direct digital receivers in future communication systems, where broad bandwidth, high effective number of bits, and low DC power consumption are an important requirement of achieving it at microwave frequencies.Due to a number of physical limitations of electrical ADC, design of an all-optical analog-todigital converter (AOADC) is pursued and presented here based on highly stable mode-locked laser based clock signal pulses for optical sampling, and a combination of leaky waveguide optical deflector using electro-optical (EO) polymers and stationary optical windows followed with high-speed photodetectors as optical quantizer. The reported principle of the AOADC is to convert a broadband RF signal into a spatially sampled light using optical deflection angle variation before quantizing it using either binary or Gray coded optical windows. The design and modeling of an AOADC working up to 20 GHz RF frequencies (with Nyquist sampling rate of over 40 GS/s) and for providing a resolution of better than 6 bits with under 4W of power consumption. Performance is currently limited by both optical and microwave attenuation in the available EO polymers.

Noise Processes and Nonlinear Mechanisms in Optoelectronic Phase-Locked Loop Using a Balanced Optical Microwave Phase Detector

“…where S i n ( f ) is the PSD of the output noise current i n (t) and S φ n ( f ) is the PSD of the equivalent phase noise caused by this current noise. We also substituted K φ from (10) to (14). With this approach, all we have to do is to find the output noise current caused by different mechanisms in the BOMPD.…”

“…This mechanism is especially important in the BOMPD, as the phase detection gain is directly proportional to the photodiode responsivity. The linear BOMPD gain formula in (10) suggests that increasing the Fig. 6.…”

“…8(b). The numerator in (53) is the same as the linear phase detector gain in (10), and for very low pulse energies, I 0 2 f ref E sat , the denominator converges to 1. At very high pulse energies, the phase detector gain becomes inversely proportional to the intensity of the optical beam.…”

“…Digital Object Identifier 10.1109/TMTT.2022.3197621 ultralow-noise microwave signal generation [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17].…”