Bryan T. Bosworth

High-speed ultrawideband photonically enabled compressed sensing of sparse radio frequency signals

We demonstrate a new architecture for high-speed compressed sensing using chirp processing with ultrafast laser pulses, presently applied to the measurement of sparse-frequency microwave signals. We spectrally encode highly chirped ultrafast laser pulses with pseudorandom bit sequences such that every laser pulse acquires a unique spectral pattern. The pulses are partially compressed in time, extending the effective sampling rate beyond the electronic limit, and then modulated with a sparse microwave signal. Finally the pulses are fully compressed and detected, effectively integrating the measurement. We achieve 100 usable features per pattern allowing for 100 points in the reconstructed microwave spectra and experimentally demonstrate reconstruction of two- and three-tone microwave signals spanning from 900 MHz to 14.76 GHz. These spectra are reconstructed by measuring the energy of only 23 to 38 consecutive laser pulses acquired in a single shot with a 500 MHz real-time oscilloscope.

High-speed flow microscopy using compressed sensing with ultrafast laser pulses.

We demonstrate an imaging system employing continuous high-rate photonically-enabled compressed sensing (CHiRP-CS) to enable efficient microscopic imaging of rapidly moving objects with only a few percent of the samples traditionally required for Nyquist sampling. Ultrahigh-rate spectral shaping is achieved through chirp processing of broadband laser pulses and permits ultrafast structured illumination of the object flow. Image reconstructions of high-speed microscopic flows are demonstrated at effective rates up to 39.6 Gigapixel/sec from a 720-MHz sampling rate.

Single-pixel imaging using compressed sensing and wavelength-dependent scattering

We demonstrate two-dimensional imaging using illumination via a single-mode fiber with a multiply scattering tip and compressed sensing acquisition. We illuminate objects with randomly structured, but deterministic, speckle patterns produced by a coherent light source propagating through a TiO2-coated fiber tip. The coating thickness is optimized to produce speckle patterns that are highly sensitive to laser wavelength, yet repeatable. Images of the object are reconstructed from the characterized wavelength dependence of the speckle patterns and the wavelength dependence of the total light collected from the object using a single photodetector. Our imaging device is mechanically scan-free and insensitive to bending of the fiber, making it suitable for micro-endoscopy.

Ultrawideband compressed sensing of arbitrary multi-tone sparse radio frequencies using spectrally encoded ultrafast laser pulses

We demonstrate a photonic system for pseudorandom sampling of multi-tone sparse radio-frequency (RF) signals in an 11.95-GHz bandwidth using <1% of the measurements required for Nyquist sampling. Pseudorandom binary sequence (PRBS) patterns are modulated onto highly chirped laser pulses, encoding the patterns onto the optical spectra. The pulses are partially compressed to increase the effective sampling rate by 2.07×, modulated with the RF signal, and fully compressed yielding optical integration of the PRBS-RF inner product prior to photodetection. This yields a 266× reduction in the required electronic sampling rate. We introduce a joint-sparsity-based matching-pursuit reconstruction via bagging to achieve accurate recovery of tones at arbitrary frequencies relative to the reconstruction basis.

Compressive fluorescence imaging using a multi-core fiber and spatially dependent scattering

We demonstrate imaging using a multi-core fiber with a scattering distal tip and compressed sensing signal acquisition. We illuminate objects with randomly structured speckle patterns generated by a coherent light source separately coupled through each fiber core to a ground glass diffuser at the distal end. Using the characterized speckle patterns and the total light collected from the object, we computationally recover pixelation-free object images with up to a seven times higher space-bandwidth product than the number of cores. The proposed imaging system is insensitive to bending of the fiber and extremely compact, making it suitable for minimally invasive endomicroscopy.

High-speed ultrawideband compressed sensing of sparse radio frequency signals

Using chirp processing of ultrafast laser pulses to perform pseudorandom measurements for compressed sensing, we successfully reconstruct multi-tone sparse-frequency microwave signals with an effective sampling rate well beyond the electronic limit.

72 MHz A-scan optical coherence tomography using continuous high-rate photonically-enabled compressed sensing (CHiRP-CS)

Randomly spectrally patterned laser pulses acquire more information in each sample, allowing for increasing imaging speed independent of detector limitations.

High-speed all-optical Haar wavelet transform for real-time image compression

We present a high-speed single pixel flow imager based on an all-optical Haar wavelet transform of moving objects. Spectrally-encoded wavelet measurement patterns are produced by chirp processing of broad-bandwidth mode-locked laser pulses. A complete wavelet pattern set serially illuminates the object via a spectral disperser. This high-rate structured illumination transforms the scene into a set of sparse coefficients. We show that complex scenes can be compressed to less than 30% of their Nyquist rate by thresholding and storing the most significant wavelet coefficients. Moreover by employing temporal multiplexing of the patterns we are able to achieve pixel rates in excess of 360 MPixels/s.

High-speed compressed sensing measurement using spectrally-encoded ultrafast laser pulses

We present a chirp processing technique for encoding pseudorandom patterns onto the spectra of broadband optical pulses for compressed sensing (CS) measurement. We demonstrate applications to characterization of ultrawideband sparse radio frequency (RF) signals and to very high-speed continuous microscopic flow imaging. In both domains, the optical sampling technique permits accurate recovery of the signals under test from only a few percent of the measurements required for conventional Nyquist sampling, significantly relaxing the required analog-to-digital conversion bandwidth and amount of data storage.

Tagging Electronic ICs using Silicon Nitride Photonic Physical Unclonable Functions

We demonstrate an on-chip photonic physical unclonable function using integrated evanescently coupled multimode spiral waveguides formed in silicon nitride with rich spectral features and validate it for use in an identification tagging application for electronic ICs.