Joseph E. Vornehm

Demonstration of a slow-light laser radar

We propose and demonstrate a proof-of-concept system for a coherently combined multi-aperture slow-light laser radar. By employing slow-light delay elements in short-pulse-emitting systems to ensure synchronized pulse arrival at the target, we show that it is possible to simultaneously achieve high resolution in the transverse and the lateral dimensions with a wide steering angle.

A slow-light laser radar system with two-dimensional scanning.

We propose a multi-aperture slow-light laser radar with two-dimensional scanning. We demonstrate experimentally that we can use two independent slow-light mechanisms, namely dispersive delay and stimulated Brillouin scattering, to dynamically compensate the group delay mismatch among different apertures, while we use optical phase locking to control the relative phases of the optical signals emitted from different apertures, as the system steers the beam in two dimensions.

Multiple-output multivariate optical computing for spectrum recognition

We describe a multivariate optical computer that can implement multiple spectral filters simultaneously. By parallel detection of multiple outputs, our proposed approach is capable of identifying more than two spectra simultaneously, and therefore could significantly speed up spectrum recognition based on optical computing. We demonstrate our approach by recognizing two rare-earth-doped glass samples and a third white light sample spectrum with a fidelity of at least 0.83.

Phase locking of multiple optical fiber channels for a slow-light-enabled laser radar system

Phase control is crucial to the operation of coherent beam combining systems, whether for laser radar or high-power beam combining. We have recently demonstrated a design for a multi-aperture, coherently combined, synchronized- and phased-array slow light laser radar (SLIDAR) that is capable of scanning in two dimensions with dynamic group delay compensation. Here we describe in detail the optical phase locking system used in the design. The phase locking system achieves an estimated Strehl ratio of 0.8, and signals from multiple emitting apertures are phase locked simultaneously to within π/5 radians (1/10 wave) after propagation through 2.2 km of single-mode fiber per channel. Phase locking performance is maintained even as two independent slow light mechanisms are utilized simultaneously.

A Slow-Light Laser Radar (SLIDAR)

Light detection and ranging (LIDAR) is used in a variety of remote sensing applications, such as measuring atmospheric properties, detecting chemical and biological agents and surveilling vehicles.1 The key performance parameters of a LIDAR system include its transverse and longitudinal resolutions.

Development of a slow-light spectrometer on a chip

We discuss the design and development of a slow-light spectrometer on a chip with the particular example of an arrayed waveguide grating based spectrometer. We investigate designs for slow-light elements based on photonic crystal waveguides and grating structures. The designs will be fabricated using electron-beam lithography and UV photolithography on a silicon-on-insulator platform. We optimize the geometry of these structures by numerical simulations to achieve a uniform and large group index over the largest possible wavelength range.

Phase Locking of SBS Slow Light in a 2.2-km Single-Mode Fiber

A stimulated Brillouin scattering (SBS) slow light system in a 2.2-km single-mode fiber was phase locked to a reference signal. Optical pulses of 6.5 ns duration were delayed 0.9 pulse width while maintaining lock.

Demonstration of a Slow-Light Laser Radar with Two-Dimensional Scanning

We demonstrate a proof-of-concept system for steering a coherently-combined multi-aperture slow-light laser radar. Each aperture incorporates slow-light elements, using dispersive delay and SBS, to ensure power overlap at the target.

Phased-Array Laser Radar System Based on Slow Light

We describe an electronically steerable laser-radar system based on a sparse phased array and the use of slow-light methods to ensure synchronization of the light leaving each subaperture.

Multi-Spectral Raman Gain in Atomic Rubidium Vapor

Optically off-resonant stimulated Raman scattering of 85-Rb is studied experimentally to implement a scheme that eliminates the key sources of fidelity loss in macroscopic entanglement and quantum information storage using atomic vapor or trapped atoms.