H.W. Li

Semiconductor optical amplifier used as an in-line detector with the signal DC-component conservation

We present in this paper a dc-coupled in-line optical detector based on a multisection semiconductor optical amplifier (SOA). The key principle is to use a voltage reference correlated with the bias voltage level by the way of a two-section or a three-section SOA. So, by means of the differential detection, the signal dc-component is kept with reduced sensitivity to temperature and bias current fluctuations. Experimental and theoretical results are presented when a two-section SOA is used and performance predictions when a three-section is employed. The obtained responsivity is -63 VNV at 40 mA and over -110 VNV at 50 mA when the input optical power, measured within the fiber, is -13 dBm. When the SOA is biased at 40 mA, the detection bandwidth is over 1 GHz when the input optical power is -4 dBm.

Analysis of an Optically Controlled Nonlinear Directional Coupler

An optically controlled nonlinear directional coupler (NLDC) to be useful in optical integrated circuits has been analyzed. The optical control is achieved through the interactions between a laser beam and surrounding semiconductor medium. The effect of plasma density, laser beam wavelength and waveguide with on the performance of the coupler including critical power has been thoroughly investigated. A far better performance compared to a simple NLDC has been achieved.

Novel architecture of optical switch based on acousto-optic interaction for telecommunication networks

We propose a novel synchronous switch for telecommunication networks at a 1.5 μm wavelength. This switch is based on the acousto-optic interaction. In this paper, we discuss about the switchs constraints to be applicable in a network, and present an acousto-optic cell architecture using planar phased array piezoelectric transducers.

Acousto-optically tuned MUX/DEMUX for DWDM applications in optical communication

In this paper an acousto-optically tuned MUX/DEMUX for DWDM application has been investigated. An acous-to-optic cell array system is used to deflect the optical beam depending on the wavelengths at high speed by using first order diffraction. These deflections are controlled by changing the rf driving frequency of the acoustic-optic cell array system. This system has low insertion loss, less cross-talk and is free from the grating wavelength drifts due to thermal variations. The numerical results for system efficiency, wavelength tuning range and acoustic frequency-optical wavelength relationship have been obtained.

Characterization of a 2×2 optical switch using an acousto-optic cell with phased array transducers

With the intention of developing devices for optical communications, we have worked upon acousto-optic deflection in the Bragg regime, at 1.55 µm wavelength. Recently, still using the acousto-optic interaction, we have taken an interest in the 2×2 switching function. In this paper, we present an acousto-optic switch architecture based on phased array transducers. This switch is made of a single TeO2 crystal, in which we superimpose two diffraction gratings created by two RF signals. First, we talk about the acousto-optic interaction, and make a general presentation of the switchs architecture. Then, we present some previous characterisations of the structure, in terms of diffraction efficiency according to the number of piezoelectric transducers electrically supplied and the RF power applied. We also study the diffracted optical beam profiles.

Microwave generation in instable injection-locked semiconductor laser

We present a method to optically generate microwaves, based on the instability enhancement of a Fabry-Perot Semiconductor Laser locked state. The produced frequencies are within the Supra High Frequency range (SHF) and may be tuned via the input power. The efficiency conversion ratio is about 400 MHz/dB and frequencies up to 8 GHz are generated. As an application we realised an all-optical frequency convolution which can be used to translate data from an optical carrier to an hertzian one.

Performance of a bidirectional optical bus with two semiconductor laser amplifiers

We present the characterization of a bidirectional optical transmission with two semiconductor lasers amplifiers which work alternately as a modulator or a photodetector. Error free transmission is achieved up to 1.555 Gb/s.