A new class of photonic channelized radio-frequency (RF) receiver is proposed and demonstrated. The new device relies on generation of high fidelity signal copies by wavelength multicasting in a self-seeded, two-pump parametric mixer. Signal copying to widely spaced wavelengths enables channelization of the full RF bandwidth using a single periodic filter. The channelization uses freely tunable frequencies of newly generated copies and eliminates the need for construction of a dense, narrowband filter bank. The new concept is demonstrated by channelization of four subcarrier channels with 1-GHz spacing and greater than 20-dB extinction ratio between extracted channels.
"Therefore RF photonic designs provide freedom to frequency translate very wideband signals, allowing receiver designs that accommodate broad bandwidth and frequency reconfigurability, and can decouple filter bandwidth and center frequency requirements. This fundamental advantage has recently been utilized by spectral signal replicating optical front ends employing either modulated frequency combs ,  or parametric signal wavelength multicasters . The recent development of precisely dispersion engineered parametric fiber optic waveguides  enables optical spectral signal multicasting , and high frequency digital  and analog  signal processing of extremely wideband RF signals. "
[Show abstract][Hide abstract] ABSTRACT: An essential capability in many applications, ranging from commercial, surveillance and defense, is to analyze the spectral content of intercepted microwave and millimeter-wave signals over a very wide bandwidth in real-time and with high resolution. A range of photonic schemes have been introduced for the real-time processing of wideband signals to overcome limitations of current conventional electronic frequency measurement approaches. Here, a novel microwave/millimeter-wave channelizer is presented based on a RF photonic front-end employing parametric wavelength multicasting and comb generation. This new technology enables a contiguous bank of channelized coherent I/Q IF signals covering extremely wide RF instantaneous bandwidth. High channel counts and wide RF instantaneous bandwidth are enabled by use of parametrically generated frequency-locked optical combs spanning >4 THz. Full field analysis capabilities of the coherent detection system are demonstrated by frequency domain analysis of 18 contiguous 1.2 GHz IF channels covering 15.5 GHz to 37.1 GHz input frequency range, and time and spectral domain analysis of a 75 GHz harmonically generated input signal. Sensitivity and dynamic range of the system are analyzed and discussed.
", , the optical de-mux in our scheme is employed to physically separate the multicast RF channels, rather than filter and spectrally shape them. The channel bandwidth of the channelizer, Á (hundreds of megahertz), is much less than the channel bandwidth spacing of the optical de-mux ( lo , tens of gigahertz). "
[Show abstract][Hide abstract] ABSTRACT: In this paper, a novel photonic-assisted broadband and high-resolution radio-frequency (RF) channelization scheme based on dual coherent optical frequency combs (OFCs), regular optical de-muxes, and I/Q demodulators is analyzed and experimentally demonstrated. The use of two coherent combs avoids precise optical alignment, and a numerical filter in digital signal processor (DSP) enables an ideal rectangular frequency response in each channel without any ultranarrow optical filters. Besides, due to the use of I/Q demodulators, ambiguous frequency estimate in direct detection is avoided. By using two coherent OFCs with the free spectrum range (FSR) of about 40 GHz, we experimentally demonstrate the channelization scheme with seven channels, 500-MHz channel spacing, and frequency coverage from 3.75 to 7.25 GHz. The input RF tones are accurately downconverted to an intermediate frequency (IF) with a maximum frequency error of 125 kHz. Meanwhile, the channel frequency response and crosstalk of the scheme are also evaluated experimentally.
"Optical channelizers consisting of or a phased array of waveguide delay lines, fiber Bragg gratings array, free-space optical diffraction grating, or Fabry-Perot etalon and incoherent source, have been proposed -. The optical mixing can be performed by cascaded external modulators, signal re-modulation, or four-wave mixing in semiconductor optical amplifier (SOA) and highly nonlinear fiber -. "
[Show abstract][Hide abstract] ABSTRACT: A photonic approach with multiple free spectral ranges (FSRs) is proposed to perform instantaneous frequency measurement. In the proposed approach, multiple channels are firstly designed with the use of multiple laser sources operating at different wavelengths and a comb filter, leading to the generation of multiple FSRs at these channels. The microwave signal with its frequency to be measured is imposed on these channels. After passing through the comb filter, optical powers at the outputs of the multiple channels are then detected and processed to estimate the frequency, with multiple FSRs or multiple measurement ranges derived during the measurement process. Such an approach is demonstrated by an experimental setup where two channels operating at 1520nm and 1550nm and a delay line interferometer based comb filter are implemented to get two different FSRs. Within the range of 12∼35GHz, the measured frequencies are in a good agreement with the input frequencies being measured.
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