Raymond K. Boncek

Performance of a 50 Gbit/s optical time domain multiplexed system using a terahertz optical asymmetric demultiplexer

Bit error rate measurements were performed on a 50 Gbit/s optical time domain multiplexed system which utilized the newly developed terahertz optical asymmetric demultiplexer (TOAD) device as the front end of a receiver. Bit error rates of less than 10/sup /spl minus/9/ were measured when 800 fj control pulses were used to gate the demultiplexer. These measurements, which were made on a 50 Gbit/s peak line-rate train, also quantified the tolerance of the TOAD to signal-control pulse jitter.<<ETX>>

DEMONSTRATION OF ULTRAFAST, ALL-OPTICAL, LOW CONTROL ENERGY, SINGLE WAVELENGTH, POLARIZATION INDEPENDENT, CASCADABLE, AND INTEGRATABLE SWITCH

A new type of ultrafast all optical switch based on a Mach–Zehnder interferometer is demonstrated with a 10 ps switching window which requires only 0.65 pJ of control pulse energy. The optical nonlinearity which is utilized is associated with the gain compression of semiconductor optical amplifiers, and the switching turnoff transition does not depend on the slow amplifier recovery time. Both data and control pulses are at the same wavelength of 1.313 μm, and are not polarized orthogonal to each other. The device configuration and the semiconductor amplifiers allow for small scale integration and data output cascadability.

Five Gb/s operation of a 50-channel optical interconnect

The architecture and experimental demonstration of a novel optical time-division multiple-access (TDMA) interconnect is presented in detail. Optical multiplexing and synchronization is used to overcome the electronic multiple-access bottlenecks associated with gigahertz-bandwidth multiprocessor communication systems. A self-clocking optical TDMA interconnect is described that may be more practical to implement than other shared-medium multiple-access protocols, such as frequency division or code division. An experimental optical TDMA interconnect is reported that uses a 100-MHz repetition rate, mode-locked laser with external modulators to generate the base-band data, and operates at a multiplexed data rate of 5 Gbits/s accommodating up to 50 channels. System measurements reveal bit error rates of less than 10 -9 , low channel crosstalk, and subnanosecond multiaccess capability. A power budget analysis predicts that 100 Gbit/s systems with 1000 nodes are feasible.

Observation of polarization‐dependent electroabsorption in (In,Ga)As/GaAs modulator structures oriented in the [110] crystallographic direction

We report room‐temperature observation of polarization‐dependent optical electroabsorption in a p‐i‐n quantum‐confined Stark‐effect modulator structure prepared from strained (In,Ga)As/GaAs layers. The strained‐layer structure is grown on a vicinally oriented (110)‐GaAs substrate.

Polarization-insensitive terabit optical demultiplexer for TDMA networks

We have developed a demultiplexer known as a Colliding Pulse Mach- Zehnder (CPMZ) suitable for OTDM systems capable of ultrafast all- optical demultiplexing and address recognition. Recently we have demonstrated a polarization and wavelength independent device, called a Terabit Optical Demultiplexer, which is capable of all-optical demultiplexing of Tbit/s pulse train with 650 fJ of switching energy, and which can be integrated on a chip. This device has achieved a 10 ps switching window. Both devices are wavelength compatible with all of the low loss transmission windows of optical fibers.

Optoelectronic feedback sustained pulsation of laser diodes at 1300 nm and 780 nm

In this paper, experimental results are reported on optoelectronic feedback sustained pulsation in multi-quantum well InGaAsP laser diodes at 1300 nm and AlGaAs injection laser diodes at 780 nm. The feedback intensity plays an important role in feedback sustained pulsation in these two different kinds of laser diodes. When the feedback exceeds a certain level, the frequency of feedback sustained pulsation exhibits continuous, but staircase-like, dependence on the drive current with two characteristic slopes. The values of these slopes depend on the feedback level. Further, at appropriate feedback levels, there exists a bistability between the oscillation frequency and the drive current. The amplitude of feedback sustained pulsation can be modulated for subcarrier multiplexing applications. By further increasing the feedback level, period doubling phenomena was also observed in this dynamical system.

Novel multiple quantum well modulators for optical interconnects

Novel multiple quantum well (MQW) optical modulators for use in time-division optical fiber interconnects are presented. A bit-error-rate analysis of a time-division receiver indicates high contrast ratio optical gates are required for high-speed interconnect applications. A high contrast MQW gate, consisting of a nonlinear asymmetric reflection modulator, suitable for use in optical time-division systems is presented which utilizes the GaAlInAs alloy lattice- matched to InP. This system is ideal for optical interconnect applications since MQW materials and devices are easily designed for operation in the optical fiber transmission windows of 1.3 and 1.5 micrometers . Utilizing asymmetric double quantum wells (ADQWs) as the nonlinear spacer for the asymmetric reflection modulator also is discussed. The recovery time of ADQWs can be tailored for interconnect applications by choosing the optimum width of the tunnel barrier. Electro-optic modulators which utilize real space transfer of electrons in ADQWs also are presented.

Demonstration of an optically transparent ATM packet switch node

We report on the development of a transparent optical node at 1.3 micrometers wavelength for an ATM packet switch operating at 1.24416 Gbit/s header recognition rates. The node takes advantage of the high-speed performance of optoelectronic components to alleviate potential bottlenecks resulting from optical to electrical conversion experience in nontransparent packet switching architectures. The node is intended for use in two-connected, slotted networks, is self-clocking, and has drop/add multiplexing, buffering, and routing capabilities.

Characterization of strained-layer and asymmetrically coupled multiple-quantum-well electro-optic modulators

Multiple quantum well (MQW) electro-optic modulators grown on both GaAs and InP substrates have been designed and characterized. Strained-layer (In,Ga)As/GaAs p-i-n diodes grown on (100) GaAs substrates were found to have a differential absorption coefficient of 3.7 X 103 cm-1 for an applied electric field of 6.6 X 104 V/cm. These devices were also grown on (110) GaAs substrates and exhibited polarization sensitive electroabsorption. In addition, InGaAs/InAlAs asymmetric coupled MQWs were designed and fabricated. Real charge transfer kinetics between the coupled MQWs were exhibited by these devices.

Performance of a terahertz optical asymmetric demultiplexer in a 50-Gbit/s optical time division-multiplexed system

We have measured the performance of a new demultiplexing device, known as a Terahertz Optical Asymmetric Demultiplexer, while operating it in an optical time division multiplexed system with an aggregate bandwidth of 50 Gbits/s. These measurements also illustrate the devices adjustable tolerance to jitter.