High speed optical modulators are important for a number of applications served by silicon photonics. Here we present our recent work towards high speed free carrier accumulation based optical modulators where a high speed and efficient operation is achieved. Such silicon optical modulators typically need to be built in sub-micrometre sized waveguides which are challenging to couple light to and from. Also presented are experimental results from a buried 3D-taper that is able to couple efficiently between a waveguide of height ~1.5um and a 220nm high waveguide. Losses below 0.6dB are achieved limited by the loss of the material used.

This talk discusses the application of silicon photonics technology to LiDAR using the Frequency Modulated Continuous Wave (FMCW) method. The presentation will feature measurement results from silicon photonic-based FMCW LiDAR systems and will highlight future developments for the technology. Additionally, real results, as demonstrated by the first fully integrated silicon photonics FMCW chip, will be shared with a focus on the value of critical vector measurements of polarization intensity, velocity and motion. The presentation will explain how coherent 4D imaging can take full advantage of all of the information that the light carries back when interacting with objects.

Development of integrated photonics enables unprecedented scaling of optical systems with small and cost-effective architectures, which is instrumental for the penetration of photonics solutions to a vast variety of new applications. To this end, mid-IR integrated photonics is emerging as a key technology for advanced sensing applications. We demonstrate the first DBR lasers exploiting on-chip integration of GaSb gain elements and silicon photonics circuit for wavelength conditioning. The hybrid integrated DBR laser delivers a maximum power of 6.0mW in CW mode at room temperature, with a narrow spectrum around 2µm. The integration scheme enables wavelength scaling beyond 3 µm.

We report electroluminescence originating from L-valley transitions in n-type Ge/Si0.15Ge0.85 quantum cascade structures centred at 3.4 and 4.9 THz. . Different strain-compensated heterostructures, grown on a Si substrate by ultrahigh vacuum chemical vapor deposition, have been investigated. The design employs a vertical optical transition and the observed spectral features are well described by non-equilibrium Green’s function calculations. We observe two emission peaks that are due to a non-selective injection in the upper state of the radiative transition. Comparison with similar III-V emitters is used to deduce radiative efficiencies. We will present new results from 4 quantum well Ge/SiGe emitters based on diagonal transitions in real space.

We study the scattering behavior of silicon nanoblocks in various displacements with respect to the optical axis of a tightly focused linearly polarized Gaussian beam. Experimentally, the laser scanning image of a single nanoblock deviates significantly from coherent image convolution. Theoretically, with exact Cartesian multipole decomposition, the results are explained through generation of high-order multipoles at large focus displacement and multipole interference. Surprisingly, due to the high-order multipoles, the efficiency of photothermal nonlinearity and Raman scattering are better with displaced focus. Our result extends Mie theory with displaced tight focus, opening up new opportunities in nanoscale light-matter interactions.

Mid-IR emitters grown on silicon will be simpler to process and less expensive to manufacture than devices grown on GaSb. Here we report interband cascade light emitting devices grown on 4° offcut silicon. While core heating limited cw emission from epi-up devices on GaSb, dissipation via the substrate allowed devices on silicon to operate to much higher currents. Accounting for differences in architecture, the efficiency was approximately 75% of that for the best previous epi-down ICLEDs grown on GaSb. At 100 mA, 200-µm-diameter mesas produced 184 µW cw at T = 25 °C and 140 µW at 85 °C.

We recently proposed a quantum computing platform that exploits circuit-bound photons to create cluster states and achieve one-way measurement-based quantum computations on arrays of photonically interfaced solid-state spin qubits with long coherence-times. Single photons are used for spin initialization, readout and for photon-mediated long-range entanglement creation. In this conference talk, we elaborate on the challenges that are faced during any practical implementation of this architecture by breaking it down into the key physical building blocks. We further discuss the constraints imposed on the spin qubits and the photonic circuit components that are set by the requirements of achieving fault-tolerant performance.