Michel Allovon

Very low drive voltage optical waveguide modulation in an InGaAs/InAlAs superlattice

We report the first room‐temperature observation of Wannier–Stark localization under waveguide configuration in a short‐period InGaAs‐InAlAs superlattice. Using the ‘‘oblique’’ transition connecting a hole localized in a well with an electron localized in the adjacent well we have achieved a modulator having a 20 dB extinction ratio and a 3 dB attenuation with a drive voltage as low as 0.8 V. Our device is a 560‐μm‐long waveguide operating at 1.55 μm under TE polarization mode.

Electroabsorption modulator based on Wannier–Stark localization with 20 GHz/V efficiency

We report on a ridge‐waveguide modulator based on Wannier–Stark localization in an InGaAs/InAlAs superlattice. Anisotropic absorption is measured and efficient modulation is obtained in the low‐field domain and in the high‐field domain with TE‐polarized light. The device exhibits outstanding HF characteristics: in terms of bandwidth‐to‐drive‐voltage ratio, we find that the Wannier–Stark localization is far more efficient than the quantum Stark effect.

Wannier-Stark localization in a 1.55 mu m InGaAs/InAlAs superlattice waveguide modulator structure

The authors present an optical waveguide modulator structure based on Wannier-Stark localization in a InGaAs-InAlAs superlattice. Optical waveguide transmission below the superlattice bandgap displays expected F/sup -1/ oscillatory behavior leading to various modulation schemes. An 11 dB extinction ratio was obtained by applying a 0.7 V drive voltage to a 100 mu m long waveguide device operating at 1.55 mu m under a transverse-electric (TE)-polarization mode. On-state attenuation was 5 dB. Lower open-state attenuation (3 dB) can be obtained simultaneously with a higher extinction ratio (13 dB) but in that case a larger drive voltage (1.6 V) is needed.<<ETX>>

Monolithic integration on InP of a Wannier Stark modulator with a strained MQW DFB 1.55-μm laser

We present the technical approach and the preliminary device results on the first integration of a Wannier Stark (WS) electroabsorption (EA) modulator with a DFB laser on InP. The WS modulator active layer consists of a lattice matched InGaAs-InAlAs superlattice (SL) grown by solid source MBE. It is butt-coupled to a laser grown by AP-MOVPE whose active layer includes a strained InGaAsP-InGaAsP MQW stack. Device results cover static performances of integrated lasers and modulators, and measurements of high frequency characteristics (small signal bandwidth and 10 Gb/s eye diagram).<<ETX>>

Compatible laser emission and optical waveguide modulation at 1.5 μm using Wannier–Stark localization

We investigate the electroabsorption properties of an InGaAs‐InAlAs superlattice optical waveguide. When reverse biased, the structure exhibits large extinction ratios over short waveguide lengths with very low drive voltages by using low‐energy oblique transitions below the superlattice band gap. Although the structure has been optimized for modulation, laser emission is observed under forward bias. The peak emission wavelength stands in the ‘‘blue‐shift’’ region which opens a way to straightforward laser‐modulator monolithic integration.

Efficient optical waveguide modulation based on Wannier-Stark localization in a InGaAs-InAlAs superlattice

We report the observation of Wannier-Stark localization in a InGaAs-InAlAs superlattice waveguide. Using the oblique transition connecting electrons and holes localized in adjacent wells we achieve efficient intensity modulation at 1 . 57jim incident light wavelength under TE polarization mode. A 16 dB extinction ratio is obtained by applying a 0. 75V drive voltage to a 320 j. tm long waveguide. On-state attenuation is only 3 dB.

Laser-modulator compatibility in an InGaAs/InAlAs superlattice structure

An InGaAs/InAlAs p-i-n double heterostructure was grown on n-type InP substrate by MBE (molecular beam epitaxy). This structure was optimized for optical waveguide modulation based on Wannier-Stark localization. The intrinsic region contains a strongly coupled superlattice. The superlattice PL (photoluminescence) linewidth is 2.4 meV at 10 K, indicating very high material quality. Under reverse bias, Wannier-Stark localization was observed on photocurrent spectra up to room temperature. Both fundamental and oblique transitions are very sharp with strong excitonic behaviors. Optical waveguide modulation performances were characterized on a 100- mu m-long device operating under TE polarization mode. The performances obtained at phonon energy below the superlattice bandgap are illustrated. Although the structure was optimized for modulation, laser emission was observed under forward bias.<<ETX>>