Larry Buhl

Wide Bandwidth Silicon Nitride Grating Coupler

We demonstrate a one-dimensional grating coupler in silicon nitride with a 67-nm 1-dB bandwidth, the largest reported for a grating coupler butt-coupled to standard single-mode fiber. The peak coupling efficiency is -4.2dB. It requires no partial etch and requires only 0.6-μm fabrication resolution.

Monolithically Integrated 40-Wavelength Demultiplexer and Photodetector Array on Silicon

We demonstrated a 40-channel dense-wavelength-division-multiplexed (DWDM) monolithically integrated receiver on silicon, which consists of a silicon nitride (Si3N4)arrayed waveguide grating (AWG) demultiplexer with integrated germanium-on-silicon waveguide photodetectors. Net responsivities from a cleaved standard single-mode fiber to detectors of 0.15 ~ 0.22 A/W are measured, with flattened passbands with 1-dB bandwidth over 60% of the 200-GHz channel spacing. Single-channel operation up to 40 Gb/s is demonstrated with a SiGe transimpedance amplifier.

Space-division multiplexing and all-optical MIMO demultiplexing using a photonic integrated circuit

We demonstrate a silicon photonic integrated circuit for all-optical demultiplexing of and selective coupling to the six spatial and polarization modes of a few-mode fiber (FMF). We successfully demultiplex all six modes after transmission through 30 km of FMF.

High Symbol Rate Coherent Optical Transmission Systems: 80 and 107 Gbaud

We demonstrate high speed optical transmission systems using digital coherent detection at all-electronically multiplexed symbol rates of 80 and 107 Gbaud. At 107 Gbaud, we demonstrate a single-carrier polarization division multiplexed quadrature phase shift keyed (PDM-QPSK) line rate of 428 Gb/s. At 80 Gbaud, we achieve a single-carrier line rate of 640 Gb/s using PDM 16-ary quadrature amplitude modulation (16-QAM). Using two optical subcarriers, we demonstrate a 1-Tb/s optical interface and conduct long-haul wavelength-division multiplexed (WDM) transmission on a 200-GHz grid over 3200 km of ultra-large effective area fiber.

Method for PMD vector monitoring in picosecond pulse transmission systems

A method and a device are proposed that allow measurement of the polarization mode dispersion (PMD) in a transmission line without data traffic interruption. The PMD vector information is extracted from the optical data signal spectrum. The method is experimentally verified by measuring of first-order PMD.

A 107-Gbit/s Optoelectronic Receiver Utilizing Hybrid Integration of a Photodetector and Electronic Demultiplexer

A novel 107-Gbit/s optoelectronic receiver has been designed using hybrid integration of a photodiode and electronic demultiplexer. Using an ETDM transmitter, we achieve the lowest reported required OSNR for 107-Gbit/s CSRZ-OOK, 21 dB for 10-3 BER and a 231-1pattern length. Design methodology and performance data are presented.

Demonstration of an Integrated Buffer for an All-Optical Packet Router

An integrated silica 10-channel, AWG-based delay-line optical buffer with up to 100 ns delay is demonstrated. Error-free operation at 40 Gb/s is shown for all channels with penalties of ∼2–4 dB at BER = 10⁻⁹.

A Programmable 8-bit Optical Correlator Filter for Optical Bit Pattern Recognition

We demonstrate a compact reconfigurable 8-bit optical matching filter fabricated using 4% delta high-index-contrast silica-on-silicon waveguides. This planar lightwave circuit is based on an eighth-order tap-and-delay finite impulse response architecture. Multimode interference-based splitters/combiners along with variable optical attenuators and phase shifters allow us to tune and dynamically reconfigure all the taps and delays (filter coefficients) in the filter using a simple automated algorithm. The filter is designed to recognize 8-bit patterns in 40-Gb/s data streams and we demonstrate its working principle by successfully correlating 8-bit binary phase-shift-keyed patterns.

All-ETDM 80-Gbaud (160-Gb/s) QPSK Generation and Coherent Detection

A single-polarization 160-Gb/s (80-Gbaud) electronically time-division-multiplexed (ETDM) quadrature phase-shift-keyed (QPSK) signal is generated and coherently detected using two 45-GHz-bandwidth oscilloscope prototypes and offline processing.

All-ETDM 80-Gbaud (640-Gb/s) PDM 16-QAM Generation and Coherent Detection

A single-carrier 640-Gb/s polarization-division multiplexed 16-ary quadrature amplitude modulation signal is generated using electronic multiplexing to 80 Gbaud. Coherent detection and off-line signal processing equalize the limited bandwidth of the transmit and receive hardware.