The rapid evolution of the silicon photonics platform has delivered a whole series of photonic integrated components and circuits, generating a critical need for on-chip power increase and preservation. In this paper, we present the design, fabrication and experimental evaluation of an InP-based electrically injected photonic crystal (PhC) nanoamplifier integrated on SOI waveguide circuitry for intra-chip communications. The principle of the device is based on the use of 2D line defect PhC waveguides made of InP-based materials, which are coupled to the SOI waveguide through optimized highly efficient adiabatic mode transformers. The InP-based slab incorporating a 400nm PIN junction, with 4 InGaAsP quantum wells emitting around 1.3µm, is drilled with PhCs so as to form a single mode waveguide at the operating wavelength. Die-to-die adhesive bonding of the InP heterostructure on SOI is performed and the nanoamplifiers are structured in the III-V layers using 2 levels of electron beam lithography followed by inductively coupled plasma etching. Through proper positioning of the metallic contacts on the sides of the structure, this particular electro-optical configuration allows for the efficient electrical injection of electron-hole pairs without inducing large optical losses. Specific efforts were made as well, so as to optimize the stimulated emission efficiency. The device operates at room temperature in a continuous wave regime at the 1.3μm window and exhibits a diode voltage threshold of around 0.6V. Detailed performance analysis of the device is presented.
The convergence of microelectronics and photonics on a single chip is one of the greatest challenges of present research. To make it happen, it is necessary to develop an entire novel class of optoelectronic devices exhibiting far beyond the state-of-the-art performance in term of compactness, speed and power efficiency. Silicon photonics enhanced with III-V semiconductors such as InP-based materials is the key technology to provide a platform able with all the necessary functionalities but it is only through the exploitation of nanophotonics concepts that disruptive performance can be reached.
During this presentation, we will show our latest results obtained on electrically powered InP-on-SOI photonic crystal devices. These results will concern first the demonstration of nanolaser diodes emitting at 1.55µm in a SOI waveguide with a wall-plug efficiency higher than 10%. The developed electrical injection scheme allows us, also, to conceive nano-amplifiers and electro-optical modulators which show promising features for their integration in a photonic circuit.
Resonant four-wave-mixing in microcavities has recently proven to be particularly interesting for obtaining ultra-efficient nonlinear wavelength conversion, parametric and frequency combs generation. Contrarily to the commonly used microring or whispering gallery mode cavities, photonic crystal nanocavities have not revealed yet their full potential in this direction. Despite their high-Q and ultra-small modal volume, they are not evidently suited for resonant four wave mixing as they do not naturally exhibit modes at equally spaced frequencies, a necessary condition for energy conservation.
In this work, we designed and fabricated 1D photonic crystal nanobeam cavities which exhibit ultra- high Q modes around 1.55µm equally spaced in frequency. These nanocavities are made of InGaP material bonded on top of a SOI waveguide optical circuitry. The evanescent wave coupling between the cavities and the waveguides can be controlled at will by changing the SOI waveguide width. The large electronic bandgap of InGaP inhibits 2 photon absorption at 1.55µm and allows us to exploit pure Kerr nonlinearity.
The electromagnetic potential inside the cavity is shaped to be spatially parabolic by engineering the hole position along the cavity. Thus, by construction the resonant modes supported by the cavity are equispaced in frequency.
The measured loaded Q factors exceed 105 and the free spectral range (FSR) goes from 150GHz to 1THz depending on the size of the cavity. We demonstrate that the FSR remains quasi constant (flat dispersion). Four wave mixing and parametric generation is observed using CW pump power of few mWs.
The development of energy-efficient ultra-compact nanolaser diodes integrated in a Silicon photonic platform is of paramount importance for the deployment of optical interconnects for intra-chip communications.
In this work, we present our results on InP-based electrically injected photonic crystal (PhC) nanolaser integrated on a SOI waveguide circuitry. The lasers emit at room temperature in a continuous wave regime at 1560nm and exhibit thresholds of 0.1mA at 1V. We measure more than 100μW of light coupled into the SOI waveguides giving a wall-plug efficiency greater than 10%.
The principle of the lasers relies on the use of a 1D PhC nanocavity made of InP-based materials positioned on top of a SOI waveguide to enable evanescent wave coupling. More in details, the laser cavity is a 650nm-wide rib waveguide drilled with a single row of equally sized holes (radius~100nm). The distance between the holes is varied to obtain Q-factors larger than 106 for a structure fully encapsulated in silica with material volume of the order of the cubic wavelength. Vertically, the InP heterostructure is a 450nm thick NIP junction embedding 5 strained InGaAsP quantum wells emitting at 1.53μm.
By smartly positioning the metallic contacts, this configuration enables the efficient electrical injection of electron-holes pairs within the cavity without inducing optical losses which led us to demonstrate the laser emission coupled ta a Si waveguide.
We present a GaAs-based VCSEL structure, BCB bonded to a Si<sub>3</sub>N<sub>4</sub> waveguide circuit, where one DBR is substituted by
a free-standing Si<sub>3</sub>N<sub>4</sub> high-contrast-grating (HCG) reflector realized in the Si<sub>3</sub>N<sub>4</sub> waveguide layer. This design enables
solutions for on-chip spectroscopic sensing, and the dense integration of 850-nm WDM data communication transmitters
where individual channel wavelengths are set by varying the HCG parameters. RCWA shows that a 300nm-thick Si<sub>3</sub>N<sub>4</sub>
HCG with 800nm period and 40% duty cycle reflects strongly (<99%) over a 75nm wavelength range around 850nm. A
design with a standing-optical-field minimum at the III-V/airgap interface maximizes the HCG’s influence on the
VCSEL wavelength, allowing for a 15-nm-wide wavelength setting range with low threshold gain (<1000 cm<sup>-1</sup>).