Zhibo Qu

Suspended silicon mid-infrared waveguide devices with subwavelength grating metamaterial cladding.

We present several fundamental photonic building blocks based on suspended silicon waveguides supported by a lateral cladding comprising subwavelength grating metamaterial. We discuss the design, fabrication, and characterization of waveguide bends, multimode interference devices and Mach-Zehnder interferometers for the 3715 - 3800 nm wavelength range, demonstrated for the first time in this platform. The waveguide propagation loss of 0.82 dB/cm is reported, some of the lowest loss yet achieved in silicon waveguides for this wavelength range. These results establish a direct path to ultimately extending the operational wavelength range of silicon wire waveguides to the entire transparency window of silicon.

Waveguide integrated graphene mid-infrared photodetector

Group IV platforms can operate at longer wavelengths due to their low material losses. By combining graphene and Si and Ge platforms, photodetection can be achieved by using graphene’s optical properties and coplanar integration methods. Here, we presented a waveguide coupled graphene photodetector operating at a wavelength of 3.8 μm.

Group IV mid-infrared devices and circuits

In this paper we present silicon and germanium-based material platforms for the mid-infrared wavelength region and we report several active and passive devices realised in these materials. We particularly focus on devices and circuits for wavelengths longer than 7 micrometers.

Germanium and silicon photonic integrated circuits for the mid-infrared

Silicon and germanium are transparent up to approximately 8 µm and 15 µm, respectively, thus offering a range of applications in biochemical and environmental sensing, medicine, astronomy and communications. In this paper we present our recent results on germanium and silicon modulators and detectors suitable for mid-infrared communications.

Mid-infrared Ge-on-Si electro-absorption modulator

We present the first waveguide electro-absorption modulator in germanium-on-silicon material platform at 3.8 μm wavelength, based on free-carrier injection into a straight waveguide. The fabricated 1 mm long device has modulation depth of >35 dB at 7 V.

Data for Suspended silicon waveguides for long-wave infrared wavelengths

This is the dataset used to create figures 2 and 4 on the paper: Soler Penades, J. et al (2017). Suspended silicon waveguides for long-wave infrared wavelengths. Optics Letters.

Germanium Mid-Infrared Photonic Devices data

Excel file containing the data for the Germanium Mid-Infrared Photonic Devices. This being a review paper, only the data for the previously unpublished work is included.Funded by Royal Society (UF120053, Mid-IR Silicon Photonics Sources, Detectors and Sensors)