Xjm Xaveer Leijtens

Optimizing imbalance and loss in 2 /spl times/ 2 3-dB multimode interference couplers via access waveguide width

Remarkably, there exists optimum coupler access waveguide widths which give minimum imbalance. Low excess loss is also achieved at the optimum width. These model results are supported by simulations, and experimental data from InP/InGaAsP couplers.

A compact integrated InP-based single-phasar optical crossconnect

The first integrated InP-based polarization independent optical crossconnect is reported. The device can crossconnect signals at four wavelengths independently from two input fibers to two output fibers. Total on-chip loss is less then 16 dB. Device size is 7/spl times/9 mm/sup 2/.

A compact digitally tunable seven-channel ring laser

A seven-channel ring laser was realized by monolithic integration of a compact 4/spl times/4 PHASAR (de)multiplexer with four amplifiers in InP. The PHASAR was fabricated using a double-etch technique, enabling a total size of the ring laser of only 1/spl times/1.5 mm/sup 2/. Light was coupled out via the outer array waveguides. Reflections are minimized by using mode filters and angled facets. Threshold-currents of 70 mA and a sidemode suppression ratio of 40 dB were measured. In principle, a ring laser with N amplifiers can produce 3N-3 different wavelengths.

S-matrix oriented CAD-tool for simulating complex integrated optical circuits

A design tool for simulation of complex integrated optical circuits, based on a professional microwave design system has been developed. Implementation of a number of components is described and a simulation example of an add-drop node using a 4/spl times/4 phased array is presented.

Integrated Tunable Quantum-Dot Laser for Optical Coherence Tomography in the 1.7

In this paper, we present the design and characterization of a monolithically integrated tunable laser for optical coherence tomography in medicine. This laser is the first monolithic photonic integrated circuit containing quantum-dot amplifiers, phase modulators, and passive components. We demonstrate electro-optical tuning capabilities over 60 nm between 1685 and 1745 nm, which is the largest tuning range demonstrated for an arrayed waveguide grating controlled tunable laser. Furthermore, it demonstrates that the active-passive integration technology designed for the 1550 nm telecom wavelength region can also be used in the 1600-1800 nm region. The tunable laser has a 0.11 nm effective linewidth and an approximately 0.1 mW output power. Scanning capabilities of the laser are demonstrated in a free space Michelson interferometer setup where the laser is scanned over the 60 nm in 4000 steps with a 500 Hz scan frequency. Switching between two wavelengths within this 60 nm range is demonstrated to be possible within 500 ns.

\mu{\rm m}

We present a compact 16-channel digitally tunable laser integrated on InP with the possibility to produce groups of four wavelengths at the same time. The cavity contains two arrays of four semiconductor optical amplifiers (SOAs) with two periodical four-channel intracavity phased arrays (PHASARs) with channel spacings of 100 and 400 GHz. By activating two out of the eight SOAs, 16 different wavelengths can be selected. Light was coupled out of the cavity by waveguides placed in the second focal order of the PHASARs. Reflections from the end facets of the wafer are minimized using mode filters and angled output waveguides.

Wavelength Region

We report the first chirped multimode interference-based phased-array (MMI-PHASAR) for application in multi-wavelength lasers (MWLs). To avoid wavelength ambiguity in MWLs, undesired orders are suppressed by chirping the array of arms in the demultiplexer. Simulations show that a suppression of adjacent orders of more than 2 dB can be achieved. A 1/spl times/5 MMI-PHASAR has been realized in which the effect of the chirping is clearly visible according to the simulations.

An integrated 4 x 4-channel multiwavelength laser on InP

A waveguide photodetector (PD) based on semi-insulating (SI) indium phosphide (InP) was simulated, designed, and fabricated. The layer stack for this PD was optimized for use as an optical amplifier or laser and it can be combined with the passive components. By using an SI substrate and deep etching, a small, efficient, and high-speed PD was made, which allows for easy integration of source, detector, and passive optical components on a single chip. A 3-dB bandwidth of 35 GHz and 0.25 A/W external radio-frequency reponsivity is measured at 1.55-mum wavelength for a 1.5-mum-wide and 30-mum-long waveguide PD at -4-V bias voltage. The polarization dependence in the responsivity is less than 0.27 dB.

Chirping of an MMI-PHASAR demultiplexer for application in multiwavelength lasers

An extremely compact integrated polarisation independent optical crossconnect is reported. The device can crossconnect signals at four wavelength independently from two input fibres to two output fibres. Total on-chip loss is less than 16 dB, crosstalk is better than -16 dB. Device size is 6/spl times/6 mm/sup 2/. An improvement in performance compared to an earlier reported device has been achieved by using an optimised concept.

High-Performance InP-Based Photodetector in an Amplifier Layer Stack on Semi-Insulating Substrate

We present the design, fabrication and characterization of an InP-based membrane photodetector on an SOI wafer containing a Si-wiring photonic circuit. Measured detector responsivity and 3 dB bandwidth are 0.45 A/W and 33 GHz, respectively. The photonic device fabrication is compatible with wafer scale processing steps, guaranteeing compatibility towards future generation electronic IC processing.