Polarization, scattering, and coherent effects in semiconductor rib waveguide bends.

The detailed behavior of circular bend attenuation in GaAs/AlGaAs rib waveguides is explored both experimentally and theoretically. Our results show a strong polarization dependence of the bend loss and coherent coupling oscillations much weaker than predicted by beam-propagation calculations.

Analysis of a proposed extension to the Fabry-Perot technique for measurements of loss in semiconductor optical waveguides.

A recent paper by Clark and Iqbal [Opt. Lett. 15, 1291 (1990)] proposed a novel modification of the conventional Fabry-Perot technique for measuring losses in semiconductor optical waveguides, which they claim eliminates the need for any knowledge of the reflectivities of the waveguide end facets. We show that the range of validity of this technique is quite limited and in many situations may be difficult to verify.

Quenching of resonantly enhanced absorption by multimode interference in vertically coupled waveguide photodetectors.

We show that the resonantly enhanced absorption predicted for conventional vertically coupled waveguide photodetectors by steady-state eigenanalysis can overestimate detector absorption (waveguide-to-detector coupling efficiency) owing to modal power nonorthogonality.

Optical power transfer in vertically integrated impedance-matched waveguide/photodetectors: physics and implications for diode-length reduction.

We identify the physical basis of the irregular absorption (spatial transients) observed in vertically integrated and impedance-matched waveguide/photodiodes using numerical simulations. We then show how the mechanism underlying these transients can be exploited to design diodes 500% shorter than conventional evanescently coupled waveguide/photodiodes, in order to achieve low capacitance and high-speed operation.

Use and misuse of end-facet reflections in the characterization of optical waveguide directional couplers.

From an analysis of the effects of end facet reflections on measurements of the characteristics of optical waveguide directional couplers, we show that these reflections can result in uncertainties of almost 6 dB in measurements of coupler extinction ratios. We present methods for estimating and minimizing these uncertainties. We also show that the Fabry-Perot loss measurement technique, which is widely used for measurements of single waveguides, can be used for loss measurements on directional couplers, but only for high extinction ratio devices.

GaAs/AlGaAs integrated-optic wavelength demultiplexer.

An integrated-optic dual-channel wavelength (de)multiplexer is demonstrated on a GaAs/AlGaAs heterostructure. The device, an asymmetric Mach-Zehnder interferometer, operates with a channel separation of 19 nm in the 1500-nm-wavelength range.

Ball lens reflections by direct solution of Maxwell's equations.

We calculate ball lens reflections, using the exact solution of Maxwell's equations for the scattering of a beam from a dielectric sphere. Our results are consistent to within 1 dB with measurements of backreflection to a single-mode fiber. We also calculate backreflection to an astigmatic spot laser diode.

Laser diode to single-mode fiber ball lens coupling efficiency: full-wave calculation and measurements.

We show that the coupling efficiency from a laser diode (LD) to an optical fiber through a ball lens can be calculated accurately using the exact solution to Maxwell's equations for the scattering of a beam from a dielectric sphere. Our calculated results agree closely with coupling measurements from an asymmetric LD for two different ball lenses.