Ingrid S. Lin

Photonic synthesis of broadband microwave arbitrary waveforms applicable to ultra-wideband communication

We demonstrate photonic synthesis of broadband radio-frequency (RF) waveforms suitable for ultra-wide bandwidth (UWB) systems via open-loop reflection-mode dispersive Fourier transform optical pulse shaping. Using this technique, we synthesize broadband burst, monocycle and pulsed waveforms with RF bandwidths ranging from /spl sim/1-8 GHz. Through appropriate optical waveform design, we demonstrate direct control over the shape of the RF spectrum - a capability that enables us to tailor our RF waveforms to conform to the low-power UWB spectral criteria.

Shaping the Power Spectrum of Ultra-Wideband Radio-Frequency Signals

We demonstrate the ability to tailor the power spectrum of ultra-wideband (UWB) RF waveforms via a photonics-based electromagnetic pulse shaper. We describe and experimentally demonstrate a waveform design methodology that allows us to achieve desirable power spectrum properties, such as broad bandwidth and minimal spectral ripple. As one example, we generate a 115% fractional-bandwidth impulsive waveform which spans the 3-10-GHz band, with ripple below plusmn1.5 dB over a 5-GHz band. Furthermore, by treating the RF spectral phase as a design parameter, we demonstrate how to achieve increased power spectral density. We illustrate the spectral design capabilities of our technique by presenting a variety of tailored UWB waveforms (including impulses, chirped signals, and arbitrary waveforms) with bandwidths that range from ~4 to 8 GHz

Selective Correlation Detection of Photonically Generated Ultrawideband RF Signals

We demonstrate hardware auto/cross-correlation measurements of photonically generated ultrawideband (UWB) RF burst waveforms in the 3-10 GHz range. Full delay dependent correlation studies with matched waveform pairs reveal correlation peaks ~15 dB above those obtained with nonmatching sets of waveforms. The possibility of real-time correlation detection is also explored, as are correlation measurements of waveforms that are transmitted over a short line-of-sight wireless link. With waveforms modified to precompensate for antenna dispersion, 7 dB correlation contrast between matched and nonmatched waveform pairs is obtained. Our results suggest hardware correlation detection as a possibility for processing of arbitrary waveforms in an Ultra-wideband (UWB) receiver.

Engineering of the radio-frequency spectra of ultrawideband electromagnetic waveforms via optical pulse shaping techniques

Through optical pulse shaping in the Fourier domain, we demonstrate engineering of ultrawideband radio-frequency spectra. Apodization and modulation of our optical waveforms enable generation of RF spectra that fill the 3.1 - 10.6 GHz frequency band.

Ultrabroadband Arbitrary Electromagnetic Waveform Synthesis

Recent research leverages femtosecond arbitrary waveform generation (AWG) technology to achieve synthesis of arbitrary voltage waveforms in the range of 1 to 50 GHz. This capability far exceeds the 2 GHz frequency limitation of commercial AWG technologies.

Hardware Correlation of Ultra-Wideband RF Signals Generated via Optical Pulse Shaping

We report hardware auto-and cross-correlation measurements of ultrawideband (UWU) RF waveforms generated photonically. Correlation peaks with widths in the SO to 100 ps range arc demonstrated, indicating that our waveform generation and processing setup operates over much of the 3.1-10.6 GHz UWB band.

Tailoring of the power spectral density of ultrawideband RF and microwave signals

We demonstrate that chirped RF waveforms, synthesized via optical frequency-to-time and optical-to-electrical conversion, lead to increases in RF energy of up to 10/spl times/ and RF power spectral density up to 10 dB as compared to ultrawideband impulses.

Ultrafast optics techniques for microwave/millimeter-wave arbitrary waveform generation

In this paper we review work at Purdue in which shaped optical pulses are used to drive an optical-to-electrical (O/E) converter. This leverages our femtosecond optical arbitrary waveform generation(AWG) technology to achieve generation of arbitrary voltage waveforms in the range between a few GHz and 50 GHz. A dispersive fiber is used to stretch the optical waveform duration prior to optical-to-electrical converter. The optical power spectrum is shaped using a Fourier transform pulse shaper prior to dispersive stretching.

Compression of ultra-wideband microwave arbitrary waveforms via optical pulse shaping

We report matched filtering of ultra-wideband microwave waveforms via programmable optical phase filters implemented in a hyperfine resolution pulse shaper. As an example we demonstrate compression of an 800-ps electrical chirp waveform to 42 ps.

Correlation detection of photonically-generated ultra-wideband radio-frequency waveforms over wireless link

We report correlation measurements of ultra-wideband radio-frequency signals dispersion precompensated for transmission over a short antenna link. Experimental auto- and cross-correlations of upchirped and down-chirped electrical waveforms demonstrate high contrast.