P. Rojo-Romeo

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.

InP-based two-dimensional photonic crystal on silicon: In-plane Bloch mode laser

Defectless two-dimensional photonic crystal structures have been fabricated by drilling holes in a thin multi-quantum-well InP-based heterostructure transferred onto a silicon host wafer. Extremely low group velocity modes, which correspond to the predicted photonic valence band edge, have been observed for different filling factors. Under pulsed optical pumping, room temperature laser operation around 1.5 μm has been achieved on these structures with a threshold in the milliwatt range.

Seventy-fold enhancement of light extraction from a defectless photonic crystal made on silicon-on-insulator

Very high photoluminescence extraction is observed from defectless two-dimensional photonic crystals etched in the upper 200-nm-thick silicon layer of a silicon-on-insulator (SOI) substrate. Predicted very low group velocity modes near the Γ point of the band structure lying above the light line are used to extract light from the photonic crystal slab into the free space. It is found that light is extracted on a 80-nm-wide band along directions near to the perpendicular to the slab, with an extraction enhancement up to 70 compared to an unpatterned SOI.

Group velocity and propagation losses measurement in a single-line photonic-crystal waveguide on InP membranes

Single-line photonic-crystal waveguides are investigated. Photoluminescence experiments and three-dimensional calculation are performed and allow a clear identification of the guided modes. The propagation properties of the latter (group velocity, losses) are extracted from photoluminescence spectra obtained on closed waveguides which act as linear cavities.

Nanophotonic Devices for Optical Interconnect

We review recent progress in nanophotonic devices for compact optical interconnect networks. We focus on microdisk-laser-based transmitters and discuss improved design and advanced functionality including all-optical wavelength conversion and flip-flops. Next we discuss the fabrication uniformity of the passive routing circuits and their thermal tuning. Finally, we discuss the performance of a wavelength selective detector.

Broadband and compact 2-D photonic crystal reflectors with controllable polarization dependence

Two-dimensional (2-D) compact photonic crystal reflectors on suspended InP membranes were studied under normal incidence. We report the first experimental demonstration of 2-D broadband reflectors (experimental stopband superior to 200 nm, theoretical stopband of 350 nm). They are based on the coupling of free space waves with two slow Bloch modes of the crystal. Moreover, they present a very strong sensitivity of the polarization dependence, when modifying their geometry. A compact (50/spl times/50 /spl mu/m/sup 2/) demonstrator was realized and characterized, behaving either as a broadband reflector or as a broadband transmitter, depending on the polarization of the incident wave. Experimental results are in good agreement with numerical simulations.

Heterogeneous integration of microdisk lasers on silicon strip waveguides for optical interconnects

A new approach is proposed to realize an optical link for intrachip optical interconnects. This link includes III-V compound-based laser sources and photodetectors, and silicon-on-insulator-based strip waveguides. The heterogeneous integration of an InP-based microdisk laser with a silicon waveguide using SiO/sub 2/-SiO/sub 2/ molecular bonding and nanofabrication procedures is emphasized. The technological procedure is described and first experimental results show that, with an adequate configuration, 35% of light could be coupled from the optically pumped microlaser to the waveguide, as a result of the vertical evanescent coupling.

Development of Silicon Photonics Devices Using Microelectronic Tools for the Integration on Top of a CMOS Wafer

Photonics on CMOS is the integration of microelectronics technology and optics components to enable either improved functionality of the electronic circuit or miniaturization of optical functions. The integration of a photonic layer on an electronic circuit has been studied with three routes. For combined fabrication at the front end level, several building blocks using a silicon on insulator rib technology have been developed: slightly etched rib waveguide with low (0.1 dB/cm) propagation loss, a high speed and high responsivity Ge integrated photodetector and a 10 GHz Si modulators. Next, a wafer bonding of silicon rib and stripe technologies was achieved above the metallization layers of a CMOS wafer. Last, direct fabrication of a photonic layer at the back-end level was achieved using low-temperature processes with amorphous silicon waveguide (loss 5 dB/cm), followed by the molecular bonding of InP dice and by the processing in microelectronics environment of InP sources and detector.

Analysis of hybrid photonic crystal vertical cavity surface emitting lasers.

Vertical resonators with a top mirror constituted of 1D photonic crystal membrane on top of a Bragg stack are investigated in this paper. These structures allow the fabrication of compact vertical-cavity surfaceemitting lasers, which can be designed, in addition, for in-plane emission. With this hybrid approach, fabrication problems related to both classical VCSEL and Photonic Crystal lasers may be significantly relaxed, given that a full Bragg stack is replaced by a single photonic crystal membrane and that the Photonic Crystal is not formed in the active gain layer.

Quasi-3D Light Confinement in Double Photonic Crystal Reflectors VCSELs for CMOS-Compatible Integration

A novel architecture of one-dimensional photonic crystal membrane (PCM) reflectors embodying a heterostructure is proposed as a robust design aimed at a 3-D efficient confinement of light in single-mode polarization-controlled 1.55-μm vertical-cavity surface-emitting laser (VCSEL) microsources for heterogeneous integration on complementary metal-oxide-semiconductor (CMOS). On the basis of a theoretical approach, the paper focuses on the deep interweaving between the kinetics of light transport in the mirrors and the physical nature of the exploited Fano resonances. An example of VCSEL design for optical pumping employing heterostructure-confined photonic crystal mirrors is presented. The predicted photons kinetics along with the considerable improvement in cavity modal features owing to the enhanced mirror architecture have been confirmed by performing rigorous three-dimensional finite-difference time-domain (3-D FDTD) calculations. Finally, experimental observations of photoluminescence (PL) emission performed on first-ever fabricated devices for optical pumping show striking agreement with theoretical considerations and ab initio modelling.