Matthew M. Dummer

High saturation power and high gain integrated photoreceivers

A novel monolithically integrated semiconductor optical amplifier (SOA) receiver is presented. This receiver implements a flared SOA and tapered quantum-well detector. SOAs exhibited 22-dB unsaturated gain and 15.7-dBm output power at the 1-dB gain compression point while the receiver demonstrated 15-GHz bandwidth and -10.5-dBm sensitivity.

Advanced integration schemes for high-functionality/high-performance photonic integrated circuits

The evolution of optical communication systems has facilitated the required bandwidth to meet the increasing data rate demands. However, as the peripheral technologies have progressed to meet the requirements of advanced systems, an abundance of viable solutions and products have emerged. The finite market for these products will inevitably force a paradigm shift upon the communications industry. Monolithic integration is a key technology that will facilitate this shift as it will provide solutions at low cost with reduced power dissipation and foot-print in the form of highly functional optical components based on photonic integrated circuits (PICs). In this manuscript, we discuss the advantages, potential applications, and challenges of photonic integration. After a brief overview of various integration techniques, we present our novel approaches to increase the performance of the individual components comprising highly functional PICs.

A single regrowth integration platform for photonic circuits incorporating tunable SGDBR lasers and quantum-well EAMs

A monolithic integration platform is demonstrated for high functionality photonic circuits that include quantum-well electroabsorption modulators, semiconductor optical amplifiers, and widely tunable lasers. The platform is based on the selective removal of a set of active quantum wells located above an optical waveguide layer. The waveguide layer contains a second set of quantum wells to be used in modulator regions. Fabrication requires only a single blanket InP regrowth

Separate Absorption and Modulation Mach-Zehnder Wavelength Converter

A monolithic separate absorption and moduation region (SAM) wavelength converter is demonstrated. The transmitter consists of a sampled-grating DBR (SGDBR) laser and a series-push-pull Mach-Zehnder modulator. The preamplified receiver is composed of a flared semiconductor optical amplifier and a quantum-well pin photodetector. Integrated resistors and capacitors are used to minimize microwave losses and remove the need for external bias tees. The design, fabrication, and operation of this photonic integrated circuit is presented. Small-signal response measurements show a device bandwidth in excess of 20 GHz. Operation at 40 Gbps with NRZ data shows less than a 2.5-dB power penalty across the 32-nm laser tuning range with no additional power penalty for conversion to the input wavelength.

40 Gb/s Field-Modulated Wavelength Converters for All-Optical Packet Switching

We present a high-functionality photonic integrated circuit that performs field-modulated wavelength conversion. This device incorporates an on-chip sampled grating distributed Bragg reflector laser for wide tunability. Wavelength conversion is accomplished using a preamplified semiconductor optical amplifier photodiode receiver interconnected with a traveling-wave modulator to form a high-speed optical gate. This paper discusses the design and performance of this device, as well as its potential for optical packet switching applications. Error-free wavelength conversion is demonstrated at 40 Gb/s with 1-3 dB power penalty compared with back-to-back transmission over 22 nm of input and output tuning. Output extinction in all cases is greater than 9 dB, and conversion efficiency ranges from -2 to -6 dB over the tuning range. This device additionally demonstrates the capability for external 10 Gb/s modulation, which can be used for optical label encoding.

Widely Tunable Separate Absorption and Modulation Wavelength Converter With Integrated Microwave Termination

A widely tunable wavelength converter utilizing a separate absorption and modulation configuration and only dc bias connections is demonstrated. The device integrates an SG-DBR laser with a traveling-wave electroabsorption modulator and an optically pre-amplified receiver and introduces a simplified bias scheme by the inclusion of passive resistor and capacitor circuit elements. We discuss a the design of these passive elements and their compatibility with fabrication of photonic integrated circuits. The device demonstrates over 12 GHz optical bandwidth and error free 10 Gb/s wavelength conversion is achieved with less than 2.5 dB power penalty over 25 nm of output tuning.

Recent progress on LASOR optical router and related integrated technologies

In this talk we review the latest progress on the DOD-N LASOR optical router project. Architectural studies including design and buffering will be discussed as well as prototype node performance. Recent results in integration in InP and Si/InP platforms will be described.

Periodic Loading and Selective Undercut Etching for High-Impedance Traveling-Wave Electroabsorption Modulators

For the first time, selective undercut etching and periodically loaded electrodes are combined to improve impedance and velocity matching for traveling-wave electroabsorption modulators. These devices are fabricated in a platform compatible with widely tunable lasers.

A bit-rate-transparent monolithically integrated wavelength converter

We demonstrate a monolithic wavelength converter based on a PD-EAM optical gate and tunable SGDBR laser operating at any bit rate up to 40 Gb/s in both NRZ and RZ formats.

Selectively-undercut traveling-wave electroabsorption modulators incorporating a p-InGaAs contact layer

A novel fabrication process has been developed for fabricating undercut-etched electroabsorption modulators that are compatible with tunable lasers. This process allows for the incorporation of highly doped p-type InGaAs above the upper cladding as an ohmic contact layer. The EAM demonstrates significant improvement in the microwave performance with little effect on modulation efficiency due to the undercut etching. This device uses a traveling wave electrode design with an integrated, matched termination resistor to demonstrate a 34 GHz 3-dB bandwidth for a 600 microm long modulator.