Bias effects on the electro-optic response of Ge-on-Si waveguide photodetectors

Silicon photonics, allowing for the integration of optoelectronic components into CMOS-compatible platforms, has shown great promise in the development of next-generation telecommunication systems and fast, low-power data interconnects. Within this framework, the increasing transistor integration and power dissipation density has led, during the last decades, to a steady decrease of the CMOS bias voltages. This trend may also affect the operation of silicon photonics components: the present work is focused on the effects of lower bias in Ge-on-Si waveguide photodetectors (WPDs), using the electro-optic (EO) frequency response as a figure of merit

3D multiphysics transient modeling of vertical Ge-on-Si pin waveguide photodetectors

We report transient simulations of Ge-on-Si vertical pin waveguide photodetectors (WPDs), where the optical generation term used by the time-domain model is the FDTD solution of the electromagnetic problem treated as a spatially-distributed pulsed signal. This approach, validated against experimental measurements of the frequency response, paves the way to future studies of the dynamic response of WPDs, enabling the description of complex modulation schemes including saturation effects and current tails due to slow carriers

Modeling the frequency response of vertical and lateral Ge-on-Si waveguide photodetectors: Is 3D simulation unavoidable?

Using a 3D multiphysics model as a reference, we investigate the achievements and limitations of a simpler 2D drift-diffusion model to reproduce and optimize the electrooptical frequency response of vertical and lateral Ge-on-Si waveguide photodetectors

Ge-on-Si waveguide photodetectors: multiphysics modeling and experimental validation

This work compares a multiphysics modeling approach with experimental measurements of two Ge-on-Si butt-coupled waveguide photodetectors. The coupled three-dimensional electromagnetic and electrical simulation of the frequency response shows promising agreement with the measurements at 1310 nm, and provides detailed information about significant microscopic quantities, such as the spatial distribution of the optical generation rate

Optical Power Screening Effects in Ge-on-Si Vertical Pin Photodetectors

We present an experimental and numerical study on the effects of the input optical power on the electro-optic frequency response of a Ge-on-Si vertical pin waveguide photodetector. Experimental results were provided by Cisco Systems, which characterized several nominally identical devices. Increasing the optical power from −2 dBm to 3 dBm, a significant decrease of the electro-optic frequency response was observed in the O-band, from about 40GHz down to approximately 32GHz. This trend is accurately predicted by our 3D multiphysics model, where Maxwell’s equations are solved with the FDTD method to evaluate the spatial distribution of photogenerated carriers, which is then converted in an optical generation rate included in the drift-diffusion solver. The 3D model provides a detailed explanation of the experiments by showing the effects of carrier screening on the magnitude of the electric field profile, which is reduced for high optical power, slowing the photogenerated carriers and reducing the bandwidth