![]() The phase-shifting photonic quantization (PSPQ) scheme quantizes the input analog signal based on the desired phase shifts instead of the V π scaling of different modulation transfer functions. In order to overcome this limitation while keeping the merits of optical sampling and quantization, the photonic quantization schemes based on the phase shifting ,, ,, , and the optical nonlinearity ,, ,, , have been proposed and widely studied. However, limited by the geometrically-scaled half-wave voltage ( V π) of the employed MZMs, it is hard to realize a photonic ADC with the system bit resolution higher than 4 bits even with the state-of-art photonic fabrication techniques. Taylor’s scheme attracts masses of research interests because both the sampling and quantization of the input analog signal are realized in optical domain. Till now, kinds of photonic assisted ADCs schemes have been proposed and demonstrated, which include the photonic preprocessing ADC techniques based on time-stretch technology ,, the photonic sampling and electronic quantization ADC schemes , the photonic ADC approaches based on modulators or interferometers, and the photonic quantization schemes based on optical nonlinearity, etc.Īs early in the 1970’s Taylor has proposed a photonic ADC scheme based on Mach–Zehnder modulator (MZM) array, which can realize 2 n quantization levels with n parallel MZMs . ![]() Thanks to the merits of photonic technologies and devices such as the ultra-high bandwidth offered by electro-optical modulators, the ultra-low timing jitter provided by mode-locked lasers (MLLs) and the immunity to the electromagnetic interference, the photonics-assisted ADC is regarded as the most promising candidate for overcoming the performance bottlenecks in electronic ADCs. As the emergence of more and more applications like radar and electronic warfare systems which require both wide-bandwidth and high-resolution simultaneously, the current electronic ADCs face the technological barrier to keep the high sampling rate as well as the high resolution. In addition, we also discuss the performance limitations induced by the frequency ambiguity in chirped spectra and the timing jitter in sampling.Īs the critical interface between the analog and digital worlds, the analog-to-digital converters (ADCs) play a vital role in a wide range of applications from consumer electronics to precision instrumentation to military and aerospace communications. A proof-of-concept experiment of the proposed approach based on time-to-frequency mapping is successfully carried out to verify the feasibility of the scheme. Meanwhile, it also avoids the limitation of optical nonlinearity and realizes the linear mapping between the analog voltage and optical spectrum. Compared with the existing photonic ADC schemes, the proposed approach greatly simplifies the system configuration and uses only one modulator with a dispersive element to achieve 2 N quantization levels. ![]() The optical spectral information can be directly encoded by using interleaving filters and a binary receiver array, which outputs the digital records of the input analog signal. ![]() In the approach, the amplitude of the input analog signal is firstly converted into a time-varying signal by pulse position modulation, then the time variation is mapped into the optical spectrum with the help of time-to-frequency mapping offered by the chirped optical pulse. ![]() A novel photonic analog-to-digital conversion (ADC) scheme based on time-to-frequency mapping is proposed and experimentally demonstrated. ![]()
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