K. Rauschenbach

40-Gb/s demultiplexing using an ultrafast nonlinear interferometer (UNI)

We demonstrate a 40-Gb/s demultiplexer using an ultrafast nonlinear interferometer (UNI). Bit-error-rate (BER) measurements are performed yielding incurred power penalties less than 3.3 dB for BER of 10/sup -9/.

Picosecond-accuracy all-optical bit phase sensing using a nonlinear optical loop mirror

We demonstrate picosecond-accuracy bit phase comparison using a nonlinear optical loop mirror. We use this all-optical bit phase comparator to synchronize an external cavity modelocked diode laser operating at 10-GHz to a soliton compression source operating at 10-GHz using an electrooptic phase lock loop. We believe this is the first demonstration of soliton compression source synchronization. The holding range of the phase lock loop is /spl plusmn/20 MHz, and is limited by the modelocking bandwidth of the external cavity laser. Clock acquisition time is dominated by the latency of the nonlinear optical loop mirror.<<ETX>>

20-GHz optical storage loop/laser using amplitude modulation, filtering, and artificial fast saturable absorption

An optical pulse storage ring, storing 1.76 kb of 20 Gb/s pulsed, on-off keyed, noise-generated data has been demonstrated. Stable operation is achieved using amplitude modulation, filtering, and artificial fast saturable absorption. Patterns with widely varying densities of ONEs have been stored, including patterns with all ONEs (harmonic mode-locking).<<ETX>>

Optical rate conversion for high-speed TDM networks

Rate conversion of ultrahigh-speed optical data streams to lower rate optical data streams that can be detected and processed electronically is essential in 100-Gb/s time-division multiplexed (TDM) multiaccess networks. In this letter, we demonstrate all-optical rate conversion.

Monolithic two‐dimensional surface‐emitting strained‐layer InGaAs/AlGaAs and AlInGaAs/AlGaAs diode laser arrays with over 50% differential quantum efficiencies

Monolithic two‐dimensional surface‐emitting arrays of strained‐layer InGaAs/AlGaAs and AlInGaAs/AlGaAs diode lasers have been fabricated and operated pulsed with low‐threshold current densities and differential quantum efficiencies greater than 50%. The InGaAs/AlGaAs arrays emit at 1.03 μm, while the AlInGaAs/AlGaAs arrays emit at 0.815 μm. Thus, it should be possible to fabricate monolithic arrays with comparable performance over a wide wavelength range. The individual lasers of the arrays are horizontal folded‐cavity devices with two 45° internal reflectors and two top‐surface facets. The design is simple to implement using optical pattern‐generator masks, optical projection printing, and chlorine ion‐beam‐assisted etching in key fabrication steps.

All-optical storage of a 1.25 kb packet at 10 Gb/s

An all-optical pulse storage ring storing a 1.25 kb packet at 10 Gb/s is demonstrated. Optical modulation of the transmission of a semiconductor diode amplifier via cross-gain saturation provides timing stability in the ring.<<ETX>>

Monolithic two-dimensional GaAs/AlGaAs laser arrays fabricated by chlorine ion-beam-assisted micromachining

Chlorine ion-beam-assisted etching (IBAE) has been used to micromachine laser facets and deflecting mirrors for monolithic two-dimensional GaAs/AIGaAs laser arrays. Three laser cavity/deflector designs have been successfully implemented. The first utilizes a parabolic deflecting mirror to directly focus the laser radiation; the second consists of a folded cavity with a vertical facet, a top surface facet, and an internal 45° reflector; and the third has a folded cavity with an internal Al0.2Ga0.8As/Al0.8Ga0.2As dielectric mirror stack and a top surface facet formed in a single etch step with two internal 45° reflectors. The parabolic deflecting mirrors are currently modeled forf- 0.8 collection efficiency, making the first design attractive in incoherent arrays for high-power applications such as pumping Nd:YAG lasers. The other two structures are of interest for incoherent or coherent arrays used in high- and medium-power applications, since the top surface facets can easily be antireflection coated. The design with a dielectric mirror stack is particularly simple to fabricate.

Reduced‐confinement antennas for GaAlAs integrated optical waveguides

Monolithically integrated reduced‐confinement antennas are shown to produce reductions of >35% in the far‐field beam divergence for radiation emitted from single‐mode GaAlAs slab waveguides, yielding far‐field beams as narrow as 8.2° FWHM along the direction perpendicular to the wafer surface. Reduced confinement of the guided mode near the output endface is achieved using a novel molecular beam epitaxy growth technique to produce a longitudinal variation in the refractive index and thickness of the waveguide film. Unlike present horn antennas, the reduced‐confinement geometry has the distinct advantage of being compatible with two‐dimensional antenna development.

Hybrid approach to two‐dimensional surface‐emitting diode laser arrays

A new hybrid structure for two‐dimensional surface‐emitting diode laser arrays has been demonstrated. Each hybrid array consists of linear arrays of GaAs/AlGaAs lasers, with conventional cleaved end facets, that are mounted in grooves etched in a Si substrate. The etched grooves have flat bottoms and 45° sidewalls that are coated with a highly reflecting Cr/Au layer. A hybrid array with three 4‐mm‐wide GaAs/AlGaAs linear laser arrays has been fabricated and tested. Approximately 10 W of peak power perpendicular to the array surface was obtained from each of the linear arrays for 11–12 A of pulsed current per array. The measured differential quantum efficiencies were 65–70%, indicating that the 45° metallized sidewalls deflect by 90° essentially all of the light emitted from the laser facets. The new approach allows for the use of integral Si heat sinks and should prove useful for fabricating large, high‐power, two‐dimensional laser arrays in any material system.

Monolithic Two-dimensional Surface-emitting Arrays Of GaAs/AlGaAs Diode Lasers

Monolithic two-dimensional arrays with light emission normal to the surface were obtained by fabricating edge-emitting quantum well GaAs/AlGaAs lasers with deflecting mirrors adjacent to both laser facets. The facets and mirrors were formed by ion-beam-assisted etching. Proton bombardment between adjoining lasers was used to prevent lasing in the transverse direction. At the highest pulsed current used in these experiments, 10.5 A, the power output of a 22-element array was 1.6 W, which corresponds to a power density of 160 W/sq.cm. At this level, the power output was still linear with current.