F. Alexandre

MSI InP/InGaAs DHBT technology: beyond 40 Gbit/s circuits

We present current results obtained on IC-oriented OPTO+ InP DHBT lab technology. Transistors with 180/210 GHz F/sub t//F/sub max/, current gain of 50 and BV/sub ce0/=7V are currently fabricated with >99% fabrication yield. Uniformity measurements show a standard deviation on F/sub t/ and F/sub max/ lower than 2% and lower than 5% on all investigated parameters. In a second part DHBT-specific modelling issues are discussed. A 68 Gbit/s selector has been obtained and a 40 Gbit/s master-slave D-type flip-flop (MS-DFF) has been reproducibly fabricated with >50% functional yield using this technology.

Dynamic properties of InAs∕InP (311)B quantum dot Fabry–Perot lasers emitting at 1.52μm

Dynamic properties of truly three-dimensional-confined InAs∕InP quantum dot (QD) lasers obtained by molecular beam epitaxy growth on a (311)B oriented substrate are reported. The relative intensity noise and small signal modulation bandwidth experiments evidence maximum relaxation frequency of 3.8GHz with a clear relaxation oscillation peak, indicating less damping than InAs∕GaAs QD lasers. The Henry factor amounts to ∼1.8 below threshold and increases to ∼6 above threshold, which is attributed to band filling of the thick wetting layer.

Growth and characterization of high quality BxGa1−xAs/GaAs(0 0 1) epilayers

In a first step towards the growth of BInGaAs, we have grown and characterized the B x Ga 1-x As/GaAs ternary compound with boron composition up to x = 0.06 on GaAs(0 0 1) vicinal substrates. The incorporation behavior of boron has been studied as a function of growth temperature, diborane flux, gallium precursor and carrier gas (hydrogen and nitrogen). A maximum for boron incorporation (x 0.04-0.06) is found at 550-600°C depending on the precursor and the carrier gas. The epilayers have good crystalline quality as measured by X-ray rocking curve of the (004) diffraction peak (full-width at half-maximum of 38 arcsec for x = 0.035). However, the surface morphology is very sensitive to the diborane supersaturation in the gas phase. At high diborane flow rate, the surface appears as though it is covered in dust. A low surface roughness of 0.4 nm was measured by atomic force microcopy (AFM) in the best growth conditions. AFM images also show a cross-hatch pattern for the highest boron composition.

Surface segregation of boron in BxGa1-xAs/GaAs epilayers studied by x-ray photoelectron spectroscopy and atomic force microscopy

The behavior of boron incorporation into GaAs has been studied by x-ray photoelectron spectroscopy, x-ray diffraction, and atomic force microscopy. As the boron content of the film was increased, both the characteristic peak for the B 1s core level at 188 eV and As Auger transition (260 eV) could be detected by XPS. At 550–600 °C, single crystalline films could only be grown for x⩽0.06. Upon increasing the diborane flux in the gas phase, the film stoichiometry and the boron surface composition evolved rapidly towards a boron-rich subarsenide compound. This trend is followed by a clear degradation of the surface morphology and an increase in the surface roughness. A surface segregation of boron is suggested due to the high diborane vapor supersaturation needed during growth.

A hybrid electroabsorption modulator device for generation of high spectral-efficiency optical modulation formats

We report a novel hybrid integrated optic device consisting of AlGaInAs/InP electroabsorption modulators and a four-arm silica-on-silicon planar lightwave circuit optical interferometer. The device is designed for generation of high spectral efficiency optical modulation formats. We demonstrate generation of 21.4 Gb/s quadrature phase shift keyed optical signals with electrical data drives of 2V(pp) amplitudes, achieving a bit error rate of 10(-9) with the required optical signal to noise ratio of ~18 dB in a 0.1 nm resolution bandwidth.

InP DHBT technology and design for 40 Gbit/s full-rate-clock communication circuits

In this paper, we present our InP DHBT technology with improved performances, yield and uniformity; and some new design tools, both of which have allowed us to achieve 40+ Gbit/s full-rate-clock circuits, such as the D-flip-flop. These circuits have been characterized and packaged.

10 Gbit/s Semi-Insulating Buried Heterostructure Loss-less Reflective Amplified Modulator for Wavelength Agnostic Networks

We integrated an AlGalnAs modulator-amplifier using semi-insulating buried hetrostructure and selective area growth. The reflective component exhibits insertion gain, operates at 10Gbit/s over 80nm and links bi-directional 10km SMF up to 60°C.

Pulse-carver-free 50-Gb/s RZ-DQPSK generation using hybrid photonic-integrated electroabsorption modulators

We report generation of 50-Gb/s RZ-DQPSK signal, without an external pulse carver, using an electroabsorption modulators-based hybrid modulator. We demonstrate the first error-free 50-Gb/s RZ-DQPSK generation using a semiconductor-based modulator with low drive voltages of 2.3 V.

Nitride-based long-wavelength lasers on GaAs substrates

Low bandgap nitrides, such as GaInAsN, grown on GaAs substrates have received a large amount of attention for several years as an alternative material system to the mature GaInAsP/InP semiconductor system, especially for 1.3 μm emission. However, to obtain high-quality GaInAsN material suitable for laser applications, it is required to overcome several specific growth issues, which are reviewed in this paper for the metal organic vapor phase epitaxy (MOVPE) technique as compared to MBE. We have particularly established that the incorporation of nitrogen in Ga(In)As grown by MOVPE requires specific growth conditions, which can result in strong improvement of both photoluminescence and lasing characteristics. The performance of GaAs-based long-wavelength lasers, as well as those from the recent literature, are compared to the state-of-the-art InP-based lasers.

A hybrid photonic-integrated electroabsorption modulator device for 50-Gb/s DQPSK generation

We report a compact hybrid photonic-integrated optical device consisting of AlGaInAs/InP electroabsorption modulators and a four-arm silica-on-silicon planar lightwave circuit optical interferometer. We use the device to generate 50-Gb/s NRZ-DQPSK signal with excellent performances comparable to those of the commercial lithium niobate DQPSK modulators, while requiring only 2.5Vpp drive signals.