Xaveer Xaveer Leijtens

Multimode Interference Reflectors: A New Class of Components for Photonic Integrated Circuits

Multimode interference devices are very versatile components that are often used as components for power splitting or combining in larger circuits. In this paper, we present a new class of multimode interference couplers that are designed to reflect all or part of the light. The components can act as on-chip mirrors with partial out-coupling, or they can act as compact mirrors with full reflection. We present an overview of such devices, the basic theory and practical design guidelines. Their simple layout makes these devices easy to fabricate and tolerant to fabrication errors. We fabricated devices of several types and present the experimental results.

A generic foundry model for InP-based photonic ICs

Europe is making significant investments in development of generic photonic foundry platform infrastructures for InP-based and Silicon Photonic ICs. Here we present the present status for the InP-based JePPIX platform.

Stability of a monolithic integrated filtered-feedback laser.

We experimentally and theoretically investigate the stability of a single-mode integrated filtered-feedback laser as a function of the electrically controlled feedback phase. We interpret the measurements in terms of feedback-induced dynamics, compare them with the results from a stability analysis model for conventional feedback, and find good qualitative agreement.

Monolithic Nanosecond-Reconfigurable 4

A monolithic InGaAsP/InP 4 × 4 cross-connect is designed, fabricated and demonstrated. Each of the four inputs fan out to two stages of semiconductor optical amplifier-based gates to perform broadband-input-selection and wavelength-specific-selection. Stages of parallel cyclic arrayed waveguide grating routers and wavelength-agnostic fan-ins allow independent electronically controlled routing of four unique wavelength channels between the four inputs and outputs. The circuit is realized within a 15 mm area on a multi-project wafer. Circuit performance is evaluated by resolving optical power loss within the circuit to show component level performance at and close to design specification. Data routing experiments for wavelength multiplexed signals are performed and quantified in terms of optical power penalty. Multi-path routing is performed with both co- and counter-propagating data. Bi-directional and fast reconfigurable routing is similarly quantified. Low power penalty of less than 1 dB is measured for the simultaneous routing of data over multiple circuit paths.

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We report, for the first time to our knowledge, an on-chip mode-locked laser diode (OCMLLD) that employs multimode interference reflectors to eliminate the need of facet mirrors to form the cavity. The result is an OCMLLD that does not require cleaved facets to operate, enabling us to locate this OCMLLD at any location within the photonic chip. This OCMLLD provides a simple source of optical pulses that can be inserted within a photonic integrated circuit chip for subsequent photonic signal processing operations within the chip (modulation, optical filtering, pulse rate multiplication, and so on). The device was designed using standardized building blocks of a generic active/passive InP technology platform, fabricated in a multi-project wafer run, and achieved mode-locking operation at its fundamental frequency, given the uncertainty at the design step of the optical length of these mirrors, critical to achieve colliding pulse mode-locked operation.

4 Space and Wavelength Selective Cross-Connect

An analytical model of star couplers in arrayed waveguide gratings (AWG) is derived. By retaining the real 1-D mode shapes, the model is able to calculate the star coupler response to fundamental modes, as well as higher order modes. This is desirable for modeling passband flattened AWGs. The model can calculate the response of an AWG very fast, because no numerical root finding or integral calculation is involved. This allows it to be used in circuit level simulations.

On-chip mode-locked laser diode structure using multimode interference reflectors

Earlier it was observed that polarization rotation in an AWG built from birefringent waveguides can result in sidelobes in its response. This effect was measured in a polarization sensitive AWG with an orthogonal layout. Now we investigate through detailed simulation whether this effect also exists in polarization desensitised AWGs. It is shown that a dispersion compensated AWG does not suffer from a polarization sidelobe. Alternatively, the AWG can be designed to minimize polarization rotation to suppress the sidelobe.

New Analytical Arrayed Waveguide Grating Model

In this work the design and characterization of a monolithically integrated photonic circuit acting as a reflective modulator for eight WDM channels is presented. The chip was designed and fabricated in a generic integration technology.

Sidelobes in the response of arrayed waveguide gratings caused by polarization rotation

A novel multi-wavelength laser monolithically integrated on InP is presented. The device consists of four channels of Fabry-Pérot lasers using two-port multimode interference reflectors (MIRs) and a single mode operation for each channel is realized by the filtered-feedback from arrayed waveguide grating(AWG).

Monolithically integrated 8-channel WDM reflective modulator

A novel InP-based monolithically integrated multi-wavelength detector is used as the central part of a fiber Bragg grating interrogator unit. We have designed the arrayed waveguide grating in the device such that at least two detectors have a significant signal at any wavelength being measured. Consequently, the measurement resolution is increased while keeping the area of device small. We demonstrate the resolution of the measurement to be 0.32 pm over a working range of 10 nm. The corresponding relative resolution of 0.003% is to our knowledge the best reported to date in an integrated interrogator.