Mechanical resonators based on suspended two-dimensional membranes are promising systems for developing sensitive detectors of mass, charge and force. To measure the flexural vibrations of the membrane, it is important to employ a technique capable of resolving tiny fluctuations of vibration amplitude. To this end, researchers have been developing optical detection methods based on Fabry-Perot interferences of light between the membrane and a mirror-like substrate, which relate the intensity of light reflected by the device to the distance between the membrane and the substrate. In this work, we calculate the membrane-to-substrate distances that maximize the optical responsivity of the resonator, which we define as the derivative of the resonator’s reflectivity with respect to membrane’s displacement. In addition, we examine how various substrates with different refractive indices affect this optical responsivity, including bare silicon, silicon coated with silicon oxide, dissipative metal mirrors, and non-dissipative Bragg reflectors. Our calculation method is based on the transfer matrix method for propagating electromagnetic fields. Our results are consistent with earlier theoretical and experimental results, and offer perspectives to enhance the optical responsivity of these mechanical resonators.
We report a Germanium lateral pin photodiode integrated with selective epitaxy at the end of silicon waveguide.
A very high optical bandwidth estimated at 120GHz is shown, with internal responsivity as high as 0.8A/W at
1550nm wavelength. Open eye diagram at 40Gb/s was obtained under zero-bias at wavelength of 1.55μm.
Silicon photonics has generated a growing interest with impressive results on active devices
like optical modulators and photodetectors in the last few years. In the framework of the
European project HELIOS, several research groups and industrial partners work on the main
building blocks to make high-speed optical links based on either silicon-based materials or
III-V components bonded on silicon. Here, we present an overview of the main achievements
on PN and PIPIN optical modulators based on carrier depletion and on germanium and III-V
photodetectors integrated with silicon waveguides.
This paper reports on fabrication and characterization of waveguide integrated vertical PIN Ge/Si photodetectors for operation at optical telecommunication wavelengths. The measured -3dB bandwidth of waveguide integrated photodetectors at 1.53 μm wavelength under 4 V reverse bias is 42 GHz.
A vertically illuminated photodetector based on Ge-on-SOI, which operates at 8 Gb/s for reverse bias as low as 0.5 V, is
presented. The integrated photodetector also features low dark current and good photogenerated carrier collection
This paper reports on fabrication and characterization of two kinds of photodetectors: surface illuminated and waveguide integrated vertical PIN Ge/Si photodetectors for operation at optical telecommunication wavelengths. The measured -3dB bandwidth of surface illuminated photodetectors is 40 GHz under 5 V reverse bias at 1.53 µm wavelength. For waveguide integrated photodetectors, the measured -3dB bandwidth at 1.53 µm wavelength under 4 V reverse bias is 42 GHz.