Photonic time stretch and its application to analog-to-digital conversion

Abstract

We demonstrate a new concept for analog-to-digital (A/D) conversion based on photonic time stretch. The analog electrical signal is intensity modulated on a chirp optical waveform generated by dispersing an ultrashort pulse. The modulated chirped waveform is dispersed in an optical fiber, leading to the stretching of its envelope. We have derived analytical expressions for the stretch factor and the resolution of the system. An analogto-digital converter (ADC) consisting of the photonic time-stretch preprocessor and a 1-Gsample/s electronic ADC is demonstrated. This technique is promising for A/D conversion of ultrafast signals and, hence, for realization of the digital receiver.

Optical Correlation Using Four Wave Mixing in a Highly Nonlinear Fibre for Real-Time Serialized Ultrafast Systems

“…An advantage of the serialized analog time-domain process also enables robust guided-wave architecture in functional processing systems. The manipulation of the time and frequency domain also provides design guidelines to fit in much more speed out of the already existing powerful systems [20]. Reaching the fundamental limit where the processing bandwidth is comparable to the optical bandwidth within well into the THz range.…”

Adaptive non-uniform photonic time stretch for blind RF signal detection with compressed time-bandwidth product

“…Improving the jitter and speed performance being one aspect, it is also of crucial importance to limit the overall captured data volume, i.e., time bandwidth product (TBWP) of the captured signal. Despite that PTS-ADC techniques offer greatly reduced effective Nyquist sampling rate [7][8][9][10], the record time has been increased by the same factor due to the signal stretching, resulting in an unchanged TBWP.…”

“…The initially time stretched optical pulse serves as the quasi-continuous wave optical carrier. Different from previous PTS-ADC [7][8][9][10] and AST [11][12][13][14][15] systems, in the proposed method the input RF signal is first pre-stretched by a microwave photonic phase filter with frequency-dependent time delay response before direct modulation on the stretched optical carrier at an electro-optical modulator. Thanks to the large microwave dispersion introduced by the microwave photonic phase filter, the high frequency (information-rich) components of the unknown RF signal is separated from its low frequency elements in time, leading to a frequency-chirped RF signal with its spectral-temporal profile mainly determined by the microwave photonic phase filter.…”

Two-Dimensional Spatio-Temporal Signal Processing for Dispersion Compensation in Time-Stretched ADC

“…Digital Object Identifier 10.1109/JLT.2007.896758 [6]- [8], [10]. The analog signal is slowed down prior to sampling and quantization by an electronic digitizer.…”

“…The analog signal is slowed down prior to sampling and quantization by an electronic digitizer. A practical method for implementing the time-stretch function is to use the photonic technique [8]- [10]. A linearly chirped optical pulse is generated by propagating the broadband pulses generated by a supercontinuum source in a chromatic dispersive medium such as the single mode fiber [11].…”