Compact modulated and tunable microdisk laser using vertical coupling and a feedback loop.

A study of vertical coupling conditions between microdisk based resonators and waveguides is presented using an analytical model. The coupling efficiency optimization is investigated and compared to 3D FDTD computations. We also demonstrate that coupling losses can be exploited to favor high quality factor modes in circular resonators. In addition, we propose to modify the shape of the coupled waveguide to enhance mode selectivity and obtain a very compact structure with mode hoping capacities. Lower thresholds and modulation are also expected.

Slow Bloch mode confinement in 2D photonic crystals for surface operating devices.

2D photonic crystal (2DPC) structures consisting in 2D silicon nanopillar arrays in silica are investigated. The main motivation of this work lies in that 2D rod arrays should be easily combined with refractive structures (e. g. micro-wire waveguides), unlike 2DPC consisting in hole lattices. Such an association is expected to lead to both new functionalities and larger scale integration. In this paper, we study the loss mechanism for non degenerated Bloch modes located at Gamma-point in a 2DPC slab constituted by a square lattice of silicon rods in silica. For such modes, we show that the quality factor is mainly governed by the lateral losses. To further inhibit the lateral losses, a photonic heterostructure is used. 3D FDTD calculations show that quality factors of 4000 are achieved. To reduce the vertical losses, the 2DPC heterostructure is associated with a vertical Bragg mirror, thus resulting in very high quality factors (>40000).

Electrically pumped InP-based microdisk lasers integrated with a nanophotonic silicon-on-insulator waveguide circuit.

A compact, electrically driven light source integrated on silicon is a key component for large-scale integration of electronic and photonic integrated circuits. Here we demonstrate electrically injected continuous-wave lasing in InP-based microdisk lasers coupled to a sub-micron silicon wire waveguide, fabricated through heterogeneous integration of InP on silicon-on-insulator (SOI). The InP-based microdisk has a diameter of 7.5 mum and a thickness of 1 mum. A tunnel junction was incorporated to efficiently contact the p-side of the pn-junction. The laser emits at 1.6 mum, with a threshold current as low as 0.5 mA under continuous-wave operation at room temperature, and a threshold voltage of 1.65 V. The SOI-coupled laser slope efficiency was estimated to be 30 muW/mA, with a maximum unidirectional output power of 10 muW.

Highly selective and compact tunable MOEMS photonic crystal Fabry-Perot filter.

The authors report a compact and highly selective tunable filter using a Fabry-Perot resonator combining a bottom micromachined 3-pair-InP/air-gap Bragg reflector with a top photonic crystal slab mirror. It is based on the coupling between radiated vertical cavity modes and waveguided modes of the photonic crystal. The full-width at half maximum (FWHM) of the resonance, as measured by microreflectivity experiments, is close to 1.5nm (around 1.55 microm). The presence of the photonic crystal slab mirror results in a very compact resonator, with a limited number of layers. The demonstrator was tuned over a 20nm range for a 4V tuning voltage, the FWHM being kept below 2.5nm. Bending of membranes is a critical issue, and better results (FWHM=0.5nm) should be obtained on the same structure if this technological point is fixed.

Heterogeneous integration of electrically driven microdisk based laser sources for optical interconnects and photonic ICs.

A new approach for an electrically driven microlaser based on a microdisk transferred onto Silicon is proposed. The structure is based on a quaternary InGaAsP p-i-n junction including three InAsP quantum wells, on a thin membrane transferred onto silicon by molecular bonding. A p++/n++ tunnel junction is used as the p-type contact. The technological procedure is described and first experimental results show a laser emission in pulsed regime at room temperature, with a threshold current near 1.5 mA.

Near-field probing of active photonic-crystal structures.

We report a study of the optical near field of an active integrated component operating near the 1.55-mum telecommunications wavelength. The device is based on a two-dimensional photonic crystal etched in a suspended InP membrane. Topographic as well as optical information is collected by use of a scanning near-field optical microscope in collection mode, providing information about the local distribution of the losses.