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The III-V semiconductor InGaAs is a key material for photonics because it provides optical emission and absorption in the 1.55 μm telecommunication wavelength window. However, InGaAs suffers from pronounced nonradiative effects associated with its surface states, which affect the performance of nanophotonic devices for optical interconnects, namely nanolasers and nanodetectors. This work reports the strong suppression of surface recombination of undoped InGaAs/InP nanostructured semiconductor pillars using a combination of ammonium sulfide, (NH4)2S, chemical treatment and silicon oxide, SiOx, coating. An 80-fold enhancement in the photoluminescence (PL) intensity of submicrometer pillars at a wavelength of 1550 nm is observed as compared with the unpassivated nanopillars. The PL decay time of ∼0.3 μm wide square nanopillars is dramatically increased from ∼100 ps to ∼25 ns after sulfur treatment and SiOx coating. The extremely long lifetimes reported here, to our knowledge the highest reported to date for undoped InGaAs nanostructures, are associated with a record-low surface recombination velocity of ∼260 cm/s. We also conclusively show that the SiOx capping layer plays an active role in the passivation. These results are crucial for the future development of high-performance nanoscale optoelectronic devices for applications in energy-efficient data optical links, single-photon sensing, and photovoltaics.

We report the growth, device fabrication, and performance of stacked InAs/InGaAsP/InP (1 0 0) quantum dots (QDs) in telecom lasers. Wavelength tuning of the QDs grown by metalorganic vapor-phase epitaxy (MOVPE) over the 1.55-μm region at room temperature (RT) is achieved using ultrathin GaAs interlayers underneath the QDs, which suppress As/P exchange to reduce the QD height in a controlled way. Unpolarized photoluminescence from the cleaved side, important for realization of polarization-insensitive semiconductor optical amplifiers, is obtained for closely stacked QDs due to vertical electronic coupling. The wavelength shift due to group-V-atom intermixing in the QDs during growth at higher temperatures of device structures is compensated by adjusting the GaAs interlayer thickness and V/III flow ratio during QD growth. Device quality of the QDs is highlighted by continuous-wave ground-state lasing at RT of narrow ridge-waveguide QD lasers.

We present a method to prepare a mixed resist material composed of a positive electron-beam resist (ZEP520A) and C 60 fullerene. The method is modified from previous methods in literatures to achieve an optimized mixing. An improvement of the mixed material on the thermal resistance respect to the same structures fabricated with normal ZEP resist has been demonstrated by fabricating multimode interference couplers and coupling regions of micro-ring resonators. An improvement on the propagation loss of the InP membrane waveguides from 6.6 to 3.3 dB/cm using this mixed material is also shown.

Controlled anodic oxidation for achieving a better control of etch depth in AlGaAs semiconductor structures is studied. The rates of material consumption and oxide thickness growth for p ++ -GaAs and p-Al 0.38 Ga 0.89 As are given for the citric acid/glycol/water electrolyte. The etch profiles for GaAs/Al 0.45 Ga 0.55 As and GaAs/Al 0.50 Ga 0.40 As layer sequences in laser diode structures are presented. The underetch is rather high and depends on oxidation conditions (constant voltage or constant current). The profile obtained is very rough for constant voltage oxidation and much better when using constant current conditions. The latter also improves the uniformity of oxide growth. The etch rate of the anodic oxide in diluted HCl is much larger for GaAs than for AlGaAs.

We have fabricated InP nanowire array solar cells with an axial p-n junction. Catalyst gold nanoparticles were first patterned into an array by nanoimprint lithography. The nanowire array was grown in 19 minutes by vapor-liquid-solid growth. The sidewalls were in-situ etched by HCl and ex-situ cleaned with a piranha etch. With this cleaning procedure, we could remove the sidewall extrusions and carbon contamination on the nanowire sidewall. We obtained a Voc of 0.68V, a fill factor of 71%, a diode rectification ratio of 107, an ideality factor of 2.12, a solar cell efficiency of 10.2% and a >90% device yield.

We report the formation of site-controlled InAs quantum dots (QDs) on InP pyramids and their integration into planar structures by metalorganic vapor-phase epitaxy. The QD number is reduced by the shrinking pyramid size during growth. Finally the emission from a single QD is observed at 1.55 µm, after optimization of the growth parameters. Employing regrowth epitaxy, position-controlled InAs QDs are integrated into planar InP structures. A smooth surface morphology is obtained at 640 °C during regrowth.

We developed an InP-based photodetector which was bonded on a CMOS wafer containing a Si 3 N 4 -wiring photonic circuit. The detector fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic IC processing. Integration technology and experimental results are presented in this paper.

Integrated InP/InGaAsP phased-array 1×16 optical switch is fabricated and characterized for broadband WDM optical packet switching. Wavelength-insensitive operation covering the C-band and penalty-free transmission of 40-Gbps signal are demonstrated.

Scalable quantum dot based optical switches offer energy-efficient low-latency data routing. Low power penalty routing over multiple stages are feasible with with the prospect of larger scale photonic integration.

A compact cascaded crossbar element with low power penalty, high distortion threshold and low crosstalk penalty is presented. Dual-stage monolithic switch integration is facilitated using a quantum dot epitaxy at 1550nm wavelength.

In this paper, we present a low cost and polarization independent photoreceiver which is part of the optical network unit (ONU) for the fiber access network. It consists of one InP-photodetector and a low cost SiGe amplifier. It operates error free with 223 - 1 PRBS word length at 1.25 Gbit/s with -13 dBm input optical power before the fiber chip coupling whose loss is about 5 dB. From the rise and fall time shown in measured eye diagram, it is estimated that it will also operate up to 2.5 Gbit/s.

All-optical packet switching at high bit-rates is discussed. We focus on the utilizing monolithically integrated devices to achieve high-bit-rate operation.

All-optical packet switching is discussed. In particular, we focus on the utilisation of monolithically integrated building to achieve high-bit-rate operation.

We report the first time ever fabrication and characterisation of a Cross Waveguide Grating (XWG) device.

The novel hot electron injection laser (HEL), a three-terminal vertically integrated transistor-laser structure, is designed to investigate and possibly utilize the effects of carrier-heating on the optical gain and wavelength chirp. Simulations show the potential of carrier heating assisted gain switching to directly modulate the optical field intensity at frequencies up to 100 GHz while maintaining control over the wavelength chirp. The HEL is designed to demonstrate these results through independent but complementary control over the concentration and the energy of the electrons injected into the active layer. Previous research has shown though that proper LIV behavior and a strong carrier heating efficiency requires a trade-off between electron heating and hole leakage current. Furthermore, stringent control over the epitaxial growth is crucial for these devices. Recent devices now show proper LIV behavior and strongly reduced threshold current densities around 2 kA/cm2 at room temperature. They also show the external `heating' voltage modulating the intensity of the lasing mode. The possible link between this modulation and carrier heating is further explored

We demonstrate that 80 Gb/s data-packets can be all-optically switched into two different ports employing an optical wavelength converter controlled by a monolithically integrated optical flip-flop memory. The optical wavelength converter consists of a semiconductor optical amplifier and an optical filter. The integrated optical flip-flop exhibits single-mode operation, has 35 dB contrast ratio between the states and switches state in about 2 ns. We show that the integrated flip-flop is capable to control an optical wavelength conversion up to 160 Gb/s. The system is capable of routing 80 Gb/s data packets with duration of 35 ns, separated by 15 ns of guard time.

We have developed a scanning tunneling microscope using an optoelectronic switch which gates the tunneling tip current. The switch is fabricated within several tens of microns from the tip by photolithography and an accurate cleavage method. We demonstrate this approach by detecting picosecond electrical transients on a coplanar stripline. We have investigated the signal dependence on contact resistance and found significant differences when the tip is brought from low-ohmic contact into the tunneling regime.

Etched mirror lasers offer the possibility of being integrable in Opto-Electronic Integrated Circuits (OEIC). A versatile processing technique of GaAs/AlGaAs Wet Chemically Etched Mirror Lasers (WCEML) has been developed previously. It is applicable to all laser structures in the InGaAs/AlGaAs/GaAs system. A special set of masks allowed us to vary the cavity lengths of ridge waveguide type devices from 750 /spl mu/m down to 11 /spl mu/m and ridge widths of 4, 6 and 10 /spl mu/m. The processing requires four photolithography steps. In this paper we report on the results obtained from four different GRINSCH laser structures: one having a bulk GaAs active layer (50 nm thick) while the others have 2, 3 and 5 QWs of 7 nm GaAs as an active layer respectively.

An experimental equivalent of the lumped circuit model of a photoconductively gated scanning tunneling microscope (PG-STM) is studied. This model can be used as long as the distance between the tunnel-junction and the pc-switch is small. For suitable parameters it implies a response-time below the carrier lifetime in the pc-switch.

This paper reports on low confinement (Γ= 7.5 x 10-3/well), DQW 2 x 8 nm asymmetric laser diode structure designed for high power operation [1]. The low value of Γ is achieved by adding an optical trap layer at one side of the QW’s. A significant part of the optical field is trapped in the n-type Al0.20Ga0.80As optical trap layer with a thickness cf about 0.2 μm, as shown in fig. 1.

A highly compact quantum dot semiconductor optical amplifier based crossbar switch is proposed, fabricated and demonstrated at a wavelength of 1550 nm. Power penalty measurements at 10 Gbit/s show minimal path dependence with values of 0.15 to 0.25 dB and an extinction ratio of 24 dB.

The linear polarization of the optical gain of closely stacked InAs∕InP (100) quantum dots (QDs) grown by metal-organic vapor-phase epitaxy with emission wavelength tuned into the 1.55μm region is controlled by the number of stacked QD layers and the injection current. Increasing the number of stacked QD layers to five rotates the linear polarization of the cleaved-side photoluminescence and QD ground state (GS) gain, determined from the amplified spontaneous emission (ASE) of a Fabry–Perot ridge-waveguide laser, from transverse electric (TE) to transverse magnetic due to vertical electronic coupling. When the QD GS ASE and gain saturate with an increase of the injection current and the excited state ASE and gain become dominant, the linear polarization of ASE and gain changes back to TE. This limits the polarization insensitive operation of QD-based semiconductor optical amplifiers, however, opening routes to novel functionalities.

The authors report lateral positioning and number control of InAs quantum dots (QDs) on truncated InP (100) pyramids by selective-area metal organic vapor-phase epitaxy. With reducing QD number, sharp emission peaks are observed from individual and single QDs with wavelength tuned into the 1.55μm telecom region by insertion of ultrathin GaAs interlayers beneath the QDs. Regrowth of a passive waveguide structure around the pyramids establishes submicrometer-scale active-passive integration for efficient microcavity QD nanolasers and single photon sources.

Two active Mach–Zehnder interferometers are integrated in a monolithic InP/InGaAsP photonic integrated circuit. Together they form a crucial component for optical signal processing: an optical memory element or set–reset flip-flop. The switching time for this initial device is approximately 200 ps. The photonic integrated circuit contains active and passive optical components, including electro-optic phase shifters. © 2005 Optical Society of America