Technological innovation with millimeter waves (mm waves), signals having carrier frequencies between 30 and 300 GHz, has become an increasingly important research field. While it is challenging to generate and distribute these high frequency signals using all-electronic means, photonic techniques that transfer the signals to the optical domain for processing can alleviate several of the issues that plague electronic components. By realizing optical signal processing in a photonic integrated circuit (PIC), one can considerably improve the performance, footprint, cost, weight, and energy efficiency of photonics-based mm-wave technologies. In this article, we detail the applications that rely on mm-wave generation and review the requirements for photonics-based technologies to achieve this functionality. We give an overview of the different PIC platforms, with a particular focus on hybrid silicon photonics, and detail how the performance of two key components in the generation of mm waves, photodetectors and modulators, can be optimized in these platforms. Finally, we discuss the potential of hybrid silicon photonics for extending mm-wave generation towards the THz domain and provide an outlook on whether these mm-wave applications will be a new milestone in the evolution of hybrid silicon photonics.

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We present the design of a supporting photonic crystal structure that would allow for the excitation of the predicted transverse electric (TE) polarized excitation in a single layer of graphene. We show that it is possible to measure this excitation at room temperature, and that adding an extra layer of dielectric material on top of the structure would further facilitate the experimental observation of the graphene mode.

We propose a novel semi-analytic design strategy for dielectric one-dimensional multilayer biosensors that is based on a relation between the angular sensitivity and the optical power flow of the Bloch surface wave guided by the multilayer. We show that our strategy can be used to optimize both the sensor's sensitivity and figure-of-merit without the need for extensive numerical parameter sweeps.

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A design study is presented for an efficient, compact and robust device to convert the frequency of single-photons from the near-infrared to the telecom C-band. The material platform aluminum gallium arsenide (AlGaAs)-on-insulator, with its relatively large second-order nonlinearity, is used to create highly confined optical modes. This platform can feasibly incorporate single-photon emitters such as indium arsenide (InAs) on gallium arsenide (GaAs), paving the way towards direct integration of single-photon sources and nonlinear waveguides on the same chip. In this design study, single-pass difference-frequency generation (DFG) producing C-band single-photons is enabled via form birefringent phase-matching between a 930 nm single-photon pump and continuous wave (CW) idler at 2,325 nm. In particular the idler and single-photons are combined with an on-chip directional coupler, and then tapered to a single waveguide where the three modes are phase-matched. The design is studied at a special case, showing high fabrication tolerances, and an internal conversion efficiency up to 41%.

Two photonic integrated circuits (PICs) are coupled to form a hybridly integrated semiconductor ring laser in the telecom C band with an intrinsic linewidth of (158±21) Hz. This is, to the best of our knowledge, the first time an InP active–passive platform is used in conjunction with an integrated low-loss resonator to obtain a narrow-linewidth laser implemented using generic foundry platforms. The presented results pave the way for a hybrid integrated platform for microwave photonics (MWP), as the demonstrated device includes multiple active–passive components, and its narrow optical linewidth can potentially be translated to a narrow-linewidth microwave signal. Furthermore, as the laser is based on hybrid integration of two PICs from generic foundry platforms, there is a path to reproducible and low-cost devices.

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