J.H.C. van Zantvoort

Integrated two-state AWG-based multiwavelength laser

An integrated InP-InGaAsP two-state coupled-laser device for use in optical packet switching and signal processing is presented. The two states are identified by distinct lasing wavelengths. Single-mode lasing occurs in both states and the contrast ratio between the two states is 35 dB. Switching between states with optical pulses is demonstrated. The use of an arrayed waveguide grating (AWG) and ring laser configuration permits monolithic integration without the need for cleaved facets. How the AWG can be used to obtain partial isolation between multiple interconnected devices is also discussed.

Coupled Mach–Zehnder interferometer memory element

Two active Mach-Zehnder interferometers are integrated in a monolithic InP/InGaAsP photonic integrated circuit. Together they form a crucial component for optical signal processing: an optical memory element or set-reset flip-flop. The switching time for this initial device is approximately 200 ps. The photonic integrated circuit contains active and passive optical components, including electro-optic phase shifters.

Evaluation of effects of MZM nonlinearity on QAM and OFDM signals in RoF transmitter

We present, both numerically and experimentally, the nonlinearity effect of the intensity modulator in RoF transmitters through the comparison between single-carrier QAM and multi-carrier OFDM signals. The acceptable RF power level of the multi-carrier OFDM signal is 2 dB less compared with the single-carrier signal for the same EVM penalty of 1%, indicating the degradation due to inter-modulation products caused by the modulator nonlinearity for OFDM RoF systems.

Fiber array-to-photonic-chip fixation and fine tuning using laser support adjustment

A concept for coupling lensed fiber arrays to photonic optical chips in the submicrometer range by using metal deformation is presented. Fine-tuning is possible despite already secured positions between the parts due to precisely chosen step-by-step deformations in the constructions. The smallest fine-tuning step of 0.1 /spl mu/m is measured using laser support adjustment. The system is packaged and can be temperature controlled. At a constant chip temperature of 22/spl deg/C, the package is successfully tested at an ambient temperature range of 0/spl deg/C to 60/spl deg/C.

Ultrafast All-Optical Wavelength Routing of Data Packets Utilizing an SOA-Based Wavelength Converter and a Monolithically Integrated Optical Flip–Flop

We demonstrate all-optical wavelength routing of 80 Gb/s data packets without using electronic control. The system consists of an optical wavelength converter and a monolithically integrated optical flip-flop memory. The integrated optical flip-flop is based on two coupled lasers, exhibiting single-mode operation, having a 35 dB contrast ratio between the states, and switching its state in about 2 ns. The wavelength converter is optically controlled by the optical flip-flop. We show that the optical set and reset pulses can force the optical flip-flop to switch its continuous-wave output light between two specific wavelength positions. The output light feeds the wavelength converter, which, in turn, converts the data packet into the flip-flops output wavelength, causing the data packet to be routed into a specific port.

Ultra-fast all-optical signal processing: toward optical packetswitching

We present some progress in the field of optical signal processing that could be utilized in all-optical packet switching. We demonstrate error-free 160 Gb/s optical wavelength conversion employing a single semiconductor optical amplifier. The gain recovery time of the semiconductor optical amplifier is greater than 90 ps. Assisted by an optical bandpass filter, an effective recovery time of 3 ps is achieved in the wavelength converter, which ensures 160 Gb/s operation. This optical wavelength converter can be controlled by a monolithically integrated optical flip-flop memory to route 80 Gb/s data-packets all-optically. The routing is realized without electronic control. The integrated optical flip-flop is based on two-coupled lasers, exhibits single-mode operation, has 35 dB contrast ratio between the states and switches state in about 2 ns. We demonstrate that the integrated flip-flop is able to control the optical wavelength converter up to 160 Gb/s. The system is capable of routing 80 Gb/s data packets with duration of 35 ns, separated by 15 ns of guard time.

Lensed Fiber-Array Assembly With Individual Fiber Fine Positioning in the Submicrometer Range

An innovative design is presented enabling fine positioning of each individual fiber in a fiber array used in multiinput- and multioutput-port photonic integrated circuits. Hence, the coupling efficiency of lensed fiber arrays can be improved by eliminating the eccentricities of the lenses deposited on the individual fibers and the inaccuracies of the supporting V-groove substrates. In preparation, four different types of commercially available lensed fibers are characterized and coupling efficiencies to InP-based waveguides are determined in order to select the best applicable fibers for the array. The final fiber-tip position accuracy is within plusmn0.25 mum and this design is based on metal deformation by laser-welding-induced local heat. With this technique, laser-supported adjustment is possible, allowing the opportunity of fine-tuning the fiber-tip position of already secured parts in the subassembly. Owing to the accurate fiber-tip position and the assembly of the array with selected lensed fibers, coupling efficiencies of -2.9 to -3.5 dB are simultaneously measured for four fibers to InP-based waveguides with physical dimensions of 3 mum times0.6 mum. To compare these results, the performance of different types of regular, commercially available fiber arrays, whereby the fibers are mounted on silicon V-groove substrates, are determined. In contrast, the measured coupling efficiencies are of the order of -5.2 to -7.8 dB using similar InP-based waveguides

A Tunable Si3N4 Integrated True Time Delay Circuit for Optically-Controlled K-Band Radio Beamformer in Satellite Communication

In this paper we present the design, realization, and experimental characterization of a photonic integrated true time delay circuit on a CMOS-compatible Si3N4 platform. The true time delay circuit consists of an optical side band filter for single side band modulation and an optical ring resonator for broadband time delay. Two methods of optical delay tuning are investigated: 1) optical wavelength and 2) thermo-optic delay tuning. The wavelength controlled tuning enables a large delay tuning range and can be done remotely from a distant location. The close to a linear phase measurements can be used for full beam-scanning of radio signals with frequencies in the 20 GHz band. The thermal control results in a 5 GHz RF delay bandwidth. A proof-of-concept 2 × 1 beamforming is demonstrated in the 20 GHz band. The design presented here can be employed to realize multi-beams for multi-users serviced by multiple satellites.

A dual purpose, all optical multiplexer circuit in InP, for multiplexing clock and NRZ data, and for transmultiplexing WDM to TDM

We present a new, integrated all-optical multiplexer for wavelength grooming of many WDM channels into a single TDM channel. The chips were realized in a novel generic InP foundry process. For design and mask layout of the multiplexer circuits, we developed a simple equivalent circuit, representing the incorporated wavelength converter. With the chips realized, successful WDM to TDM transmultiplexing is demonstrated, as well as multiplexing of clock and NRZ data.

Integration of laser-support fiber adjustment in opto-electronic modules

In this study, practical assembly methods are developed to connect fibers to photonic chips. In contrast to trial and error efforts using laser hammering or mechanical bending approaches, we introduce the integration of laser-assisted mechanical micro-scale deformation within the module itself. The technology is based on introducing a locally compressive plastic strain into the fiber supports. We can then obtain a predictably adequate correction of the pre-aligned fibers, a necessary step because during the fixation process degradation of the aligned positions can occur. We manufacture modules for single fiber configurations and more advanced modules for fiber-array configurations. We have also started numerical simulations of laser-adjusting to investigate further design aspects.