Nannicha Hattasan

Silicon-Based Photonic Integration Beyond the Telecommunication Wavelength Range

In this paper we discuss silicon-based photonic integrated circuit technology for applications beyond the telecommunication wavelength range. Silicon-on-insulator and germanium-on-silicon passive waveguide circuits are described, as well as the integration of III-V semiconductors, IV-VI colloidal nanoparticles and GeSn alloys on these circuits for increasing the functionality. The strong nonlinearity of silicon combined with the low nonlinear absorption in the mid-infrared is exploited to generate picosecond pulse based supercontinuum sources, optical parametric oscillators and wavelength translators connecting the telecommunication wavelength range and the mid-infrared.

Silicon-based heterogeneous photonic integrated circuits for the mid-infrared

In this paper we present our recent work on mid-infrared photonic integrated circuits for spectroscopic sensing applications. We discuss the use of silicon-based photonic integrated circuits for this purpose and detail how a variety of optical functions in the mid-infrared besides passive waveguiding and filtering can be realized, either relying on nonlinear optics or on the integration of other materials such as GaSb-based compound semiconductors, GeSn epitaxy and PbS colloidal nanoparticles.

Silicon-on-insulator spectrometers with integrated GaInAsSb photodiodes for wide-band spectroscopy from 1510 to 2300 nm

We present a silicon-on-insulator (SOI) based spectrometer platform for a wide operational wavelength range. Both planar concave grating (PCG, also known as echelle grating) and arrayed waveguide grating (AWG) spectrometer designs are explored for operation in the short-wave infrared. In addition, a total of four planar concave gratings are designed to cover parts of the wavelength range from 1510 to 2300 nm. These passive wavelength demultiplexers are combined with GaInAsSb photodiodes. These photodiodes are heterogeneously integrated on SOI with benzocyclobutene (DVS-BCB) as an adhesive bonding layer. The uniformity of the photodiode characteristics and high processing yield, indicate a robust fabrication process. We demonstrate good performance of the miniature spectrometers over all operational wavelengths which paves the way to on-chip absorption spectroscopy in this wavelength range.

Study of evanescently-coupled and grating-assisted GaInAsSb photodiodes integrated on a silicon photonic chip

In this paper we present GaInAsSb photodiodes heterogeneously integrated on SOI by BCB adhesive bonding for operation in the short-wave infrared wavelength region. Photodiodes using evanescent coupling between the silicon waveguide and the III-V structure are presented, showing a room temperature responsivity of 1.4A/W at 2.3 µm. Photodiode structures using a diffraction grating to couple from the silicon waveguide layer to the integrated photodiode are reported, showing a responsivity of 0.4A/W at 2.2 µm.

High-Efficiency SOI Fiber-to-Chip Grating Couplers and Low-Loss Waveguides for the Short-Wave Infrared

We report on high-efficiency silicon-on-insulator (SOI) grating couplers and low-loss single-mode optical waveguides operating in a short-wave infrared. A -3.8 dB coupling efficiency from a standard single-mode fiber to an SOI waveguide at 2.1 μm is obtained experimentally. Single-mode waveguide losses in the short-wave infrared below 0.6 dB/cm are reported.

Heterogeneous Integration of GaInAsSb p-i-n Photodiodes on a Silicon-on-Insulator Waveguide Circuit

We report the integration of GalnAsSb p-i-n photo diodes on a silicon-on-insulator waveguide circuit. The device operates with low dark current (1.13 μA at -0.1 V) at room temperature. A high responsivity of 0.44 A/W is measured at 2.29 μm. This yields 1.63 × 10⁹ cmHz^1/2/W of Johnson-noise-limited-detectivity.

III–V/Silicon Photonics for Short-Wave Infrared Spectroscopy

In this paper, we review our work on III-V/SOI photonic integrated circuits for short-wave infrared applications. We focus on the integration of short-wave infrared photodetectors on a silicon photonics platform and on the generation of a short-wave infrared supercontinuum using the χ(3) nonlinearity in silicon photonic wires. In addition, the performance of a silicon optical parametric amplifier is reviewed, as a first step towards constructing an integrated tunable short-wave infrared parametric oscillator.

Highly Efficient Broadband Silicon-on-Insulator Grating Couplers for the Short Wave Infrared Wavelength Range

We demonstrate broadband silicon-on-insulator fiber-to-chip grating couplers for the short wave infrared region. The devices show a peak coupling loss of -5.2 dB at 2150 nm and a 3 dB bandwidth of 160 nm.

Integrated thin-film GaSb-based Fabry-Perot lasers: towards a fully integrated spectrometer on a SOI waveguide circuit

Several molecules of interest have their absorption signature in the mid-infrared. Spectroscopy is commonly used for the detection of these molecules, especially in the short-wave infrared (SWIR) region due to the low water absorption. Conventional spectroscopic systems consist of a broadband source, detector and dispersive components, making them bulky and difficult to handle. Such systems cannot be used in applications where small footprint and low power consumption is critical, such as portable gas sensors and implantable blood glucose monitors. Silicon-On-Insulator (SOI) offers a compact, low-cost photonic integrated circuit platform realized using CMOS fabrication technology. On the other hand, the GaSb material system allows the realization of high performance SWIR lasers and detectors. Integration of GaSb active components on SOI could therefore result in a compact and low power consumption integrated spectroscopic system. In this paper, we report the study on thin-film GaSb Fabry-Perot lasers integrated on a carrier substrate. The integration is achieved by using an adhesive polymer (DVS-BCB) as the bonding agent. The lasers operate at room temperature at 2.02μm. We obtain a minimum threshold current of 48.9mA in the continuous wave regime and 27.7mA in pulsed regime. This yields a threshold current density of 680A/cm2 and 385A/cm2, respectively. The thermal behaviour of the device is also studied. The lasers operate up to 35 °C, due to a 323 K/W thermal resistance

Tunable Silicon-on-Insulator based integrated optical filters with liquid crystal cladding

We investigate the tunability of Silicon-on-Insulator (SOI) devices with liquid crystal (LC) cladding. The tuning mechanism is based on electro-optic response of the cladding to applied external electric field. The validity of this scheme is established using Mach-Zehnder interferometers (MZI). The parameters affecting the tunability of the devices are explored. Up to 20 nm shift of interference wavelength in MZI with a 150 nm thick SOI waveguide by applying 30 V is demonstrated, the highest tunability range in such designs reported to date.