E. W. Jacobs

Parametric Photonic Channelized RF Receiver

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.

Coherent Filterless Wideband Microwave/Millimeter-Wave Channelizer Based on Broadband Parametric Mixers

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.

Noise performance of phase-insensitive multicasting in multi-stage parametric mixers

Noise properties of large-count spectral multicasting in a phase-insensitive parametric mixer were investigated. Scalable multicasting was achieved using two-tone continuous-wave seeded mixers capable of generating more than 20 frequency non-degenerate copies. The mixer was constructed using a multistage architecture to simultaneously manage high Figure-of-Merit frequency generation and suppress noise generation. The performance was characterized by measuring the conversion efficiency and noise figure of all signal copies. Minimum noise figure of 8.09dB was measured. Experimental findings confirm that noise of the multicasted signal does not grow linearly with copy count and that it can be suppressed below this limit.

Photonic RF-IF wideband down conversion using optical injection locking

We describe the implementation of a self-heterodyne, tunable down converting RF-IF photonic link as a key component of a wideband microwave signal search and intercept system covering S to Ka bands. The presented architecture uses photomixing of two distributed feedback lasers injection locked to a master external cavity laser, allowing low phase to amplitude noise conversion and improved sensitivity. Coherent detection of the intermediate frequency allows unambiguous recovery of full time-domain information. The practical implementation of a packaged prototype system will be discussed, with emphasis on the system stabilization strategy and performance requirements.

High finesse compound optical ring filter for parametric multicasting RF channelization

An integrated optical compound ring filter for use in a multicast and slice channelizer/spectrum analyzer is presented. We discuss design and implementation of a SiO2 based photonic filter with 250 MHz resolution bandwidth, a flattened passband, and finesse greater than 100, enabling channelization of instantaneous bandwidths above 10GHz.

Wideband RF analyzer with 32 channels based on parametric multicasting

A staring wideband RF channelization using parametric multicasting and spectral slicing via a periodic optical filter with 32 implemented channels is presented. Parametric multicasting is technique which replicates and spectrally translates an RF signal via optical nonlinear processes. Injection locking of the pump and signal lasers to a single master laser was implemented to improve performance and stabilize pump and signal spacings. Sensitivity and dynamic range in each channel is also discussed.

Coherent detection RF-IF down converting link using injection locked laser design

A coherent detection RF-IF down converting link utilizing injection-locked distributed feedback (DFB) lasers is demonstrated. This photonic link design provides several RF performance advantages. Coherent detection allows unambiguous recovery of full time-domain I/Q IF signals. Injection locked laser design relaxes the tuning range requirement on RF local oscillators, and provides high optical power for efficient RF-IF conversion while minimizing degradation to link sensitivity due to phase noise. A cascaded injection locked configuration suppresses LO related spurious tones in the IF band is also demonstrated. Sensitivity and dynamic range data from RF C-band to Ka-band are presented.

Wideband RF channelizer based on parametric combs

RF photonic channelizers can overcome limitations of conventional electronic methods for analysis of wideband RF spectral content. Here, we will present a recent progress on the RF photonic channelizer systems that are based on optical parametric combs. These systems can analyze very wide RF bandwidths exceeding 100GHz, therefore providing essential capability for the applications demanding a wide-bandwidth spectral analysis. The RF channelizers being presented utilize parametric processes in the highly non-linear fiber mixers to generate a large number of RF signal copies in the optical domain. Two different implementations for generation of RF signal copies will be presented and compared: one using a parametric multicasting and another utilizing a direct comb modulation. Generation of optical combs spanning more than 10THz will be shown. We will also present two distinct system architectures for RF photonic channelizer system: one employing a periodic optical filter such as Fabry-Perot etalon to select channels from the signal comb, and another one utilizing a coherent detection between a frequency-locked signal comb and a parametrically generated local oscillator (LO) comb. The second scheme gives benefit of providing both in-phase and quadrature (I/Q) information on channelized intermediate frequency (IF) signals. We will present a system with 32 implemented channels using a filtered scheme and a 32-channel coherent system with a full-field detection implemented on one tunable channel. Sensitivity and dynamic range as well as benefits of both system architectures will be discussed.

Higher order planar-waveguide Bragg grating on curved waveguide

Higher order curved planar-waveguide Bragg gratings are realized by periodic width modulation. Linear chirp is achieved by width tapering. Devices were fabricated in low loss silica waveguide platform. Characterization results will be presented.