Vernier optical phased array lidar transceivers.

Optical phased arrays (OPAs) which beam-steer in two dimensions (2D) are currently limited to grating row spacings well above a half wavelength. This gives rise to grating lobes along one axis which limit the field of view (FOV), introduce return signal ambiguity, and reduce the optical efficiency in lidar applications. We demonstrate a Vernier transceiver scheme which uses paired transmit and receive phased arrays with different row periodicities, leading to mismatched grating lobe angular spacings and only a single aligned pair of transmit and receive lobes.

Fourier-basis structured illumination imaging with an array of integrated optical phased arrays.

Active imaging and structured illumination originated in "bulk" optical systems: free-space beams controlled with lenses, spatial light modulators, gratings, and mirrors to structure the optical diffraction and direct the beams onto the target. Recently, optical phased arrays have been developed with the goal of replacing traditional bulk active imaging systems with integrated optical systems. In this paper, we demonstrate the first array of optical phased arrays forming a composite aperture.

Optical isolation using microring modulators.

Optical isolators, while commonplace in bulk and fiber optical systems, remain a key missing component in integrated photonics. Isolation using magneto-optic materials has been difficult to integrate into complementary metal-oxide-semiconductor (CMOS) fabrication platforms, motivating the use of other paths to effective non-reciprocity such as temporal modulation. We demonstrate a non-reciprocal element comprising a pair of microring modulators and a microring phase shifter in an active silicon photonic process, which, in combination with standard bandpass filters, yields an isolator on-chip.

Integrated optical isolators using electrically driven acoustic waves.

We propose and investigate the performance of integrated photonic isolators based on non-reciprocal mode conversion facilitated by unidirectional, traveling acoustic waves. A triply-guided waveguide system on-chip, comprising two optical modes and an electrically-driven acoustic mode, facilitates the non-reciprocal mode conversion and is combined with spatial mode filters to create the isolator. The co-guided and co-traveling arrangement enables isolation with no additional optical loss, without magnetic-optic materials, and with low power consumption.

Mode multiplexer for guided optical and acoustic waves.

Integrated acousto-optic (AO) devices utilize the strong overlap of acoustic and optical fields in a waveguide to facilitate efficient photon-phonon (Brillouin) interactions. For example, acoustic waves offer a lossless modulation mechanism for light. "Brillouin active" photonic platforms are currently being developed that may see optical, acoustic, and AO waveguide circuits on the same chip, where guided light and sound come together in active interaction regions.

Acoustic Waveguide Eigenmode Solver Based on a Staggered-Grid Finite-Difference Method.

A numerical method of solving for the elastic wave eigenmodes in acoustic waveguides of arbitrary cross-section is presented. Operating under the assumptions of linear, isotropic materials, it utilizes a finite-difference method on a staggered grid to solve for the acoustic eigenmodes (field and frequency) of the vector-field elastic wave equation with a given propagation constant. Free, fixed, symmetry, and anti-symmetry boundary conditions are implemented, enabling efficient simulation of acoustic structures with geometrical symmetries and terminations.