A photonic integration platform is presented that allows easy manipulation and alignment of a ball lens doublet for efficient coupling between different optical components. The alignment and fixing of the lenses are automated, accurate, and highly scalable for compact parallel optical assemblies. To demonstrate this approach, we built a 4 × 25-Gb/s compact wavelength-division multiplexed transmitter with low coupling losses of ~2 dB between lasers and a planar lightwave circuit multiplexing filter.

We demonstrate an arrayed waveguide grating (AWG) demultiplexer for 3-mode few-mode fiber that obtains single-mode performance using spatial-diversity techniques and hybrid-integration. It comprises a silica AWG, and 3D-waveguide mode multiplexers and a remapping network.

We demonstrate free-space space-division-multiplexing (SDM) with 15 orbital angular momentum (OAM) states using a three-dimensional (3D) photonic integrated circuit (PIC). The hybrid device consists of a silica planar lightwave circuit (PLC) coupled to a 3D waveguide circuit to multiplex/demultiplex OAM states. The low excess loss hybrid device is used in individual and two simultaneous OAM states multiplexing and demultiplexing link experiments with a 20 Gb/s, 1.67 b/s/Hz quadrature phase shift keyed (QPSK) signal, which shows error-free performance for 379,960 tested bits for all OAM states.

We demonstrate orbital angular momentum state conversion using two 3D photonic integrated circuits for free-space communication of 20-Gb/s QPSK signals. Different combinations of OAM states show error-free performance with 379,960 bits tested.

We demonstrate a low-loss hybrid-integrated device based on a silica planar lightwave circuit (PLC) coupled to a 3-D photonic circuit that efficiently generates and multiplexes 15 optical orbital angular momentum (OAM) modes in free space.

We present a reconfigurable optical discriminator filter for frequency modulated microwave-photonics link applications. The filter is based on a simplified ring-assisted Mach-Zehnder interferometer configuration. It enables conversion of a highly linear frequency to amplitude modulation. Operations in a fixed bandwidth (BW) of 30 GHz and a tunable bandwidth from 10 to 30 GHz are achieved using third- and fifth-order filters. A balanced frequency discrimination architecture with electronically reconfigurable transfer characteristics is demonstrated. We measured a output-third order intercept point (OIP3) linearity improvement over that of a dual-output Mach-Zehnder.