A. Ougazzaden

Optical properties of low band gap GaAs(1−x)Nx layers: Influence of post-growth treatments

A detailed study on the optical quality of atmospheric pressure metalorganic vapor phase epitaxy grown GaAs(1−x)Nx epilayers (on GaAs substrates) in which the N incorporation is accomplished using dimethylhydrazine precursor is reported. We show here that the poor optical quality of these as-grown layers can be significantly improved by carefully planned post-growth heat treatments. Optical data are presented to demonstrate unambiguously that such treatments affect in no way the physical properties of these metastable layers (no phase separation) and that the improvement of their optical quality is closely connected to the incorporation behavior of N in this growth method.

Metal organic vapor phase epitaxy growth of GaAsN on GaAs using dimethylhydrazine and tertiarybutylarsine

GaAsN layers with good structural quality and surface morphology have been successfully grown on a GaAs substrate using atmospheric pressure metal organic vapor phase epitaxy. A new combination of precursors namely, dimethylhydrazine for nitrogen and tertiarybutylarsine instead of conventional arsine for arsenic, greatly facilitated growths at temperatures as low as 500 °C. Layers with N content as high as 3% and corresponding to room temperature photoluminescence (PL) peak wavelength of 1.17 μm (1.064 eV) have been obtained.

40-Gb/s tandem electroabsorption modulator

In this letter, we have developed a tandem electroabsorption modulator with an integrated semiconductor optical amplifier that is capable of both nonreturn-to-zero and return-to-zero (RZ) data transmission at 40 Gb/s. The tandem modulator consists of a broad-band data encoder and a narrow-band pulse carver. The pulse carver is able to produce 5-ps pulses with more than 20 dB of extinction. The on-chip semiconductor optical amplifier provides up to 8.5 dB of fiber-to-fiber gain and enables the modulator to be operated with zero insertion loss. Devices have been realized with greater than 40-GHz bandwidth, and 13-dB dynamic extinction for a 2.5-V swing. For optimized designs bandwidths of nearly 60 GHz: have been realized. Using these devices penalty free RZ data transmission over a 100-kin dispersion compensated fiber link has been demonstrated with a received power sensitivity of -29 dBm.

Electroabsorption modulators for high-bit-rate optical communications: a comparison of strained InGaAs/InAIAs and InGaAsP/InGaAsP MQW

Conventional high-speed (>10 GHz) external modulators at 1.55 mu m exist in various types and on several kinds of substrate material. Only electroabsorption modulators on InP have so far demonstrated polarization-independent operation at high speeds. In this paper, the properties of two strained multiple quantum well (MQW) modulators are reviewed in the context of optical fibre communications in terms of loss, drive voltage, bandwidth (>40 GHz), eye diagram, bit error rate measurements and optical power handling capacity. An effective modulation polarization sensitivity of 0.6 dB is reported. The two components differ mainly in their saturation optical power levels. A new power saturation mechanism is proposed to explain the nonlinearity of the InGaAs/lnAIAs modulator.

Monolithic integration of InGaAsP-InP strained-layer distributed feedback laser and external modulator by selective quantum-well interdiffusion

A new approach using a cap-annealing partial disordering technique is demonstrated for 1.55-/spl mu/m multiple-quantum-well (MQW) distributed feedback (DFB) laser-external electroabsorption modulator monolithic integration. Good static performances of the light source (15 mA threshold current, 14-dB on-off ratio for a 4-V voltage swing) are reported using this technique that preserves the material optical and electrical quality.<<ETX>>

Investigation of carrier heating and spectral hole burning in semiconductor amplifiers by highly nondegenerate four‐wave mixing

A highly nondegenerate (up to 1 THz) four‐wave mixing experiment is performed in a bulk semiconductor amplifier. The simultaneous presence of carrier heating and spectral hole burning shows up in a four‐wave mixing experiment. A simple physical picture is given that explains the relative weight of the two saturation mechanisms in active semiconductor devices.

High-Quality InGaAsN Growth by Metalorganic Vapor-Phase Epitaxy Using Nitrogen Carrier Gas and Dimethylhydrazine, Tertiarybutylarsine as Group V Precursors

We have successfully grown GaAsN and InGaAsN layers on GaAs substrate using atmospheric-pressure metalorganic vapor-phase epitaxy (MOVPE). Dimethylhydrazine and tertiarybutylarsine have been employed as sources of nitrogen and arsenic, respectively. To investigate the incorporation behavior of nitrogen [N] in GaAsN and InGaAsN layers as a function of ambient gas in the reactor, growth was performed in the presence of hydrogen H2 and nitrogen N2 gases. Good structural quality and surface morphology have been obtained with both gases. Furthermore, with N2 ambient gas, an enhancement of nitrogen incorporation has been observed. The nonradiative carrier lifetime is about 25 ns and is independent of the ambient gas used. This value is acceptable for laser applications.

1.3 μm strain-compensated InAsP/InGaP electroabsorption modulator structure grown by atmospheric pressure metal–organic vapor epitaxy

High quality 15-period strain-compensated InAsP/InGaP electroabsorption (EA) modulator structures have been grown by atmospheric pressure metal–organic vapor epitaxy. The incorporation of large compressive strain (∼1.7%) in the InAsP wells and tensile strain (∼−1.8%) in the InGaP barriers necessitated the growth of a few InP monolayers between the wells and barriers. The high structural quality of such samples has been demonstrated by (cross-sectional transmission electron microscopy analysis to be free of misfit dislocations and thickness undulations. The detection of a sharp and abrupt room-temperature exciton peak both in the photoconductivity and photoluminescence measurements further confirmed their excellent optical quality. 100 μm cavity length EA modulators fabricated in these structures exhibited excellent performances namely, an extinction ratio higher than 20 dB for 2.5 V drive voltage, a 3 dB bandwidth over 20 GHz, and low coupling losses to fiber (less than 2.5 dB per facet).

40 Gb/s tandem electro-absorption modulator

NRZ and RZ data transmission at 40 Gb/s are demonstrated for the first time using buried heterostructure tandem electro-absorption modulators monolithically integrated with a semiconductor optical amplifier and input/output spot-size converters. Zero penalty RZ transmission over a 100 km dispersion managed link is achieved.

Strained InGaAsP/InGaAsP/InAsP multi‐quantum well structure for polarization insensitive electroabsorption modulator with high power saturation

In this study we report a novel strained InGaAsP/InGaAsP/InAsP multiquantum well structure for electroabsorption modulators giving high power saturation together with polarization insensitivity. A careful design of the structure in terms of band‐gap engineering has been performed to fulfil both requirements. The polarization sensitivity is less than 0.5 dB for the on‐state and for a wide range of wavelengths. The carrier escape time, even at very low field, is estimated at lower than 20 ps. The transmitted power for different wavelengths is linear up to 16 dBm.