A. Rajhel

Use of multimode interference couplers to broaden the passband of wavelength-dispersive integrated WDM filters

We describe how multimode interference couplers (MMI) may be used to broaden and flatten the passband of integrated wavelength-dispersive filters. We discuss the approach and demonstrate its effectiveness with a passband-broadened InP arrayed waveguide filter operating at 1.5 /spl mu/m.

Wavelength accuracy and output power of multiwavelength DFB laser arrays with integrated star couplers and optical amplifiers

In this letter, we report the static performance of multiwavelength DFB laser arrays with integrated star couplers and optical amplifiers built for the reconfigurable optical network testbed. By the use of wavelength redundancy and proximity effect, wavelength deviations of /spl plusmn/0.2 nm or less from the designated eight-wavelength comb have been achieved with high yield. Simultaneous operation of eight wavelengths has also been demonstrated. In spite of the inherent splitting loss of 13 dB, high output powers of about -13 dBm and 0 dBm per wavelength have been measured into a single-mode fiber without and with on-chip optical amplification, respectively.

InP-based multiwavelength laser arrays with integrated combiners for WDM systems

In the Optical Network Technology Consortium, we have improved the design and fabrication of InP multiwavelength laser arrays with integrated combiners for the opical transmitters of WDM network access modules. Here we report our recent progress.

Fabrication of InP‐based wavelength division multiplexing arrayed waveguide filters using chemically assisted ion beam etching

Chemically assisted ion beam etching using Cl2 has been used to fabricate InP‐based arrayed waveguide filters that demonstrate full polarization independence and excellent performance characteristics. The process is carried out at elevated temperatures of approximately 250u2009°C to avoid difficulties associated with the low volatility of indium chlorides at lower temperatures. Optimization of the process for smooth, vertical etching is discussed. InP regrowth is successfully carried out on the etched InGaAsP guides, and measurements of the fabricated devices are presented. The adaptation of the process for angled etching is also demonstrated.

High performance polarization-independent WDM filtering using an InP reflective arrayed waveguide grating

Summary form only given. We report a high-performance polarization-independent InP arrayed waveguide grating (AWG) filter employing a compact reflective geometry. Here, we show that square-core AWGs may be realized in a reflection geometry, and still provide high quality filtering. Successful use of a reflective AWG geometry will permit advanced AWG-based components to be made with smaller die-sizes.

Suppression of modal birefringence in InP-InGaAsP waveguides through use of compensated tensile strain

We show that the modal birefringence of InP-based planar guides can be significantly reduced through the action of compensated tensile strain. By using low bandgap tensile and higher bandgap compressive layers, the material birefringence of the former may be made to dominate and provide significant modal birefringence suppression. The suppression attained is much greater than can be achieved through the application of tensile strain alone.

Performance study of a 10-wavelength DFB laser array with integrated electroabsorption modulators

We report the performance of the 10-wavelength DFB laser array with small wavelength dependence of output power, extinction ratio, frequency response and chirp parameter. The active layer consists of six strain compensated quantum wells grown on top of the modulator waveguide layer. Over a wavelength span of 15 nm, the average power into a single mode fiber varies from -3 to 0 dBm (@80 mA), with better than -12 dB (@2 V) extinction ratio, a bandwidth of 5 GHz and chirp parameter less than 1.

Monolithic multiwavelength lasers for WDM lightwave systems

We review the progress of multiwavelength DFB laser arrays made for multiwavelength optical networks. The goal is to reduce the per-wavelength transmitter cost in manufacturing and network element control. Using photonic integration, we have addressed and resolved several important issues related to laser arrays such as wavelength accuracy, output power and optical packaging. State of the art results are summarized and its impact on the multiwavelength optical network is assessed.

Progress in wavelength conversion by difference-frequency generation in AlGaAs waveguides

Significant technological progress in wavelength conversion by difference-frequency-generation (DFG) has taken place since its conception for wavelength-division-multiplexing (WDM) network applications in 1991. This paper reviews progress in wavelength conversion by DFG in AlGaAs waveguides and discusses its implications for WDM network applications. The measured conversion efficiency versus the input wavelength is shown for two input polarizations. An extremely broad tuning curve is demonstrated with /spl sim/90 nm bandwidth and a polarization independent conversion process. Simultaneous conversion of 17 channels is also shown. Here, arbitrary input polarizations were used, and each channel achieves identical conversion efficiency. One of the important considerations for network applications is a requirement for an effective means to filter unwanted channels. One such method is based on polarization diversity, and a measured spectrum exploiting the unique polarization characteristics of the conversion process in an AlGaAs waveguide is also given.

Advances in monolithic InP grating-based WDM components

This paper reviews the state-of-the-art of monolithic integration of InP grating-based WDM components. We will discuss the two basic types of InP integrated wavelength demultiplexers: the etched reflection grating spectrograph and the phased-array demultiplexer. They will be compared in terms of their performance and ease of fabrication. Current trends and examples of integration with active components will be presented. In addition, the crucial issue of the wavelength precision of these devices will be addressed.