Multi-Channel Radio Photon Receiving Path
Different block diagrams of microwave photonics receiver are considered. The scheme of multichannel microwave photonics receiver is proposed based on vertical–cavity surface–emitting lasers, increased number of channels due to additional type of multiplexing based on vortex and received high frequency signals downconverted to intermediate frequency with the use of just one reference electro–optic modulator. For the input signals with limited bandwidth, another approach for photonic ADC can be used, in which every input signal spectral interval is processed by its own channel, and the width of the spectral interval is adjusted with the performance of an electronic ADC used for digitizing. In many cases, joint processing of the output signals of all channels is not necessary; otherwise, outputs of all channels can be Fourier–processed and concatenated to get complete spectrum of a wideband microwave input signal. For realization of this scheme, continuous wave laser, electro–optic modulators, narrow band optical filters and other passive components can be used. The use of amplitude modulators, together with the phase modulators in a strongly nonlinear regime, at sufficiently high input power of the microwave signal (overmodulation) makes it possible to create a comb generator with dozens of equidistant spectral frequencies with a small amplitude flatness less than 1 dB. Performance capabilities for signal ADC using spectral intervals are derived with numerical simulation and compared with experimental results. Parameters for optimal system operation are studied. It is shown that, for modern photonic components, 8–10 effective bits can be achieved in the digitized signal.
Теги: amplitude modulators fast photonic adc microwave photonics microwave photonics filters narrow band optical filters phase modulators vcsel vortex. амплитудные модуляторы быстрый радиофотонный ацп вортексы лазер с прямой модуляцией радиофотоника радиофотонные фильтры фазовые модуляторы
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