H. P. LeBlanc

Monolithic InP/InGaAsP/InP Grating Spectrometer for the 1.48-1.56 μm Wavelength Range

We report a two‐dimensional grating spectrometer implemented in an InP/InGaAsP/InP planar waveguide for use in the low‐loss 1.5 μm wavelength fiber band. The spectrometer uses a single vertical‐walled focusing reflection grating to disperse 78 channels, spaced at 1 nm intervals, with diffraction‐limited resolution (∼0.3 nm) and a high channel isolation (≳19 dB). The spectrometer may be used such that it is insensitive to the state of the input polarization.

Use of multimode interference couplers to broaden the passband of wavelength-dispersive integrated WDM filters

We describe how multimode interference couplers (MMI) may be used to broaden and flatten the passband of integrated wavelength-dispersive filters. We discuss the approach and demonstrate its effectiveness with a passband-broadened InP arrayed waveguide filter operating at 1.5 /spl mu/m.

Simultaneous Multiple Wavelength Operation of a Multistripe Array Grating Integrated Cavity Laser

Simultaneous multiple‐wavelength operation of a multistripe array grating integrated cavity laser is reported. We demonstrate simultaneous lasing from a single output port at 2, 3, and 4 discrete wavelengths, each independently selected from a comb of 9 wavelengths set at ∼2 nm intervals, from 1512 to 1528 nm. Signal cross talk is examined for the case of two‐wavelength emission and found to be independent of the wavelength separation. The emission wavelengths were linearly spaced to within ±0.02 nm, while the comb’s central wavelength deviated by less than 2 nm from its design value. This is the highest wavelength linearity and accuracy so far recorded for a monolithic multiwavelength source.

Wavelength‐selectable laser emission from a multistripe array grating integrated cavity laser

We report laser operation of a multistripe array grating integrated cavity (MAGIC) laser in which the wavelength of the emission from a single output stripe is chosen by selectively injection pumping a second stripe. We demonstrate a device that lases in the 1.5 μm fiber band at 15 wavelengths, evenly spaced by ∼2 nm. The single‐output/wavelength‐selectable operation, together with the accurate predefinition of the lasing wavelengths, makes the MAGIC laser a very attractive candidate for use in multiwavelength networks.

High-speed performance of OMCVD grown InAlAs/InGaAs MSM photodetectors at 1.5 mu m and 1.3 mu m wavelengths

A report is presented on the fabrication of high-speed In/sub 0.53/Ga/sub 0.47/As metal-semiconductor-metal (MSM) photodetectors incorporating a high-quality lattice-matched InAlAs barrier enhancement layer, grown by organometallic chemical vapor deposition (OMCVD). Fast responses of approximately 55 ps full-width half-maximum at 1.5 mu m and approximately 48 ps at 1.3 mu m wavelengths are observed, corresponding to intrinsic device bandwidths of approximately 8 GHz and approximately 11 GHz, respectively. The absence of any tail to the pulse response, and of any low-bias DC gain, indicates a low-trap density at the InAlAs/InGaAs heterointerface. Bias independent dark currents of 10-20 mu A are observed below breakdown, which occurred at >30 V in devices with a 500-A-thick InAlAs layer.<<ETX>>

High-frequency performance of InGaAs metal-semiconductor-metal photodetectors at 1.55 and 1.3 μm wavelengths

The high‐speed performance of InGaAs interdigitated metal‐semiconductor‐metal (M‐S‐M) photodetectors illuminated with 1.55 and 1.3 μm wavelength radiation is modeled using a two‐dimensional transit time calculation. Excellent agreement is found with the experimental pulse response of detectors with interdigital spacings of 2 and 3 μm. We study the dependence of the bandwidth on the device dimensions, and also examine the quantum efficiency. The results should aid the design of InGaAs M‐S‐M detectors with the optimum combination of bandwidth and efficiency for a given application.

Corrections to "Observation of Prolonged Power Transients in a Reconfigurable Multiwavelength Network and Their Suppression by Gain-Clamping of Optical Amplifiers"

We observe channel power transients lasting several seconds in a reconfigurable multiwavelength network, which includes cascaded automatic channel power equalizers and fiber amplifiers in 1018- and 1898-km fiber links. Such prolonged power transients occur upon reconfiguration of the network due to coupling between the feedback control loops of the channel power equalizers and their interaction with the delay through the fiber link. Experiments performed under numerous conditions support this hypothesis. In particular, we experimentally demonstrate that gain-clamping of the amplifiers in the network significantly suppresses the power transients.

Fast high‐efficiency integrated waveguide photodetectors using novel hybrid vertical/butt coupling geometry

We report a novel coupling geometry for integrated waveguide photodetectors−a hybrid vertical coupling/butt coupling scheme that allows the integration of fast, efficient, photodetectors with conventional double heterostructure waveguides. It can be employed to yield a planar, or pseudo‐planar, surface that supports further levels of integration. The approach is demonstrated with a 25‐μm‐long p‐i‐n detector integrated with an InP/InGaAsP/InP waveguide, which displays a high (∼90%) efficiency and large (∼15 GHz) bandwidth. This is the fastest high‐efficiency integrated waveguide photodetector reported to date.

Efficient InGaAsP/InP multiple quantum well waveguide optical phase modulator

We report an InGaAsP/InP multiple quantum well optical phase modulator which has a high phase modulation efficiency and low loss modulation over the entire 1.5–1.56 μm fiber band. For a 4‐mm‐long device, π phase modulation requires a modulation voltage of only 0.6 V at 1.49 μm and 1.1 V at 1.55 μm wavelength. The absorption modulation for a 0–5 V bias change is negligible at 1.55 μm, rising to 0.7 cm−1 at 1.49 μm. The spectral dependence of the electrorefraction from the quantum‐confined Stark effect has also been measured for the first time over a wide continuous wavelength range. Far from the absorption edge the electrorefraction decreases approximately as the square of the energy detuning.

Butt-coupled InGaAs metal-semiconductor-metal waveguide photodetector formed by selective area regrowth

We report the monolithic integration of an InGaAs metal‐semiconductor‐metal Schottky barrier photodetector with a butt‐coupled InP/InGaAsP/InP waveguide, where the latter is formed by selective area regrowth using organometallic chemical vapor deposition. A fast pulse response (60–65 ps full width at half maximum, with no discernible tail) and a high quantum efficiency (∼80%) were observed for 1.3 μm guided light with the detector biased at 7 V. A thin InAlAs Schottky barrier enhancement layer limited the dark current to ∼28 nA at this bias.