High-efficiency large-angle Pancharatnam phase deflector based on dual-twist design.

We have previously shown through simulation that an optical beam deflector based on the Pancharatnam (geometric) phase can provide high efficiency with up to 80° deflection using a dual-twist structure for polarization-state control [Appl. Opt.54, 10035 (2015)]. In this report, we demonstrate that its optical performance is as predicted and far beyond what could be expected for a conventional diffractive optical device. We provide details about construction and characterization of a ± 40° beam-steering device with 90% diffraction efficiency based on our dual-twist design at a 633nm wavelength.

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 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.

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.