This paper describes an efficient fiber to submicron silicon waveguide coupling based on an inversely tapered silicon waveguide embedded in a SiO2 waveguide that is suspended in air. The inverse taper waveguide consist of a 50um long and 240nm thick silicon that linearly taper in width from 500nm to 120nm, which is embedded in SiO2. The SiO2 waveguide is 6um wide and 10um long. The simulation results show that the coupling loss of this new approach is 2.7dB including the interface loss at the input and output. The tolerance to fiber misalignment at the input of the coupler is 2um in both horizontal and vertical directions for only 1.5dB additional loss.
This paper presents the design and simulation of a novel piezoelectric actuator integrated with on-chip piezoresistive sensors for micro-lens actuation. COMSOL Multiphysics is used to perform and facilitate the design and simulation. The actuator consists of eight d31 mode unimorph piezoelectric actuators symmetrically attached to a lens holding frame through springs at one end, and to the silicon substrate at the other end. Diffused p-Si piezoresistors with doping of 1x1018cm-3 are considered in the proposed design for displacement sensing of each micro-actuator. Results shows 3.2μm/V displacement sensitivity for the micro-lens actuator and piezoresistive sensitivity of 0.134mV/V/μm is obtainable with p-Si piezoresistors.
In this paper, a high-speed on-chip optical displacement sensing and self-actuating mechanisms have been designed and
simulated for an AFM application. This mechanism can allow significantly smaller cantilever beams to be made with
higher sensitivity and wide bandwidth for parallel imaging through array of cantilevers. This arrangement consists of a
Si-waveguide in which a nano-scale free space gap is fabricated in the direction of light propagation.One portion of the
Si-waveguide is a suspended cantilever with a thin film PZT formed on it for actuation. The optical power coupling loss
between the waveguides is used to measure the cantilever displacement. The simulation results show that the device can
achieve a 6.25MHz resonant frequency in air, 0.195N/m spring constant and less than 0.1nm sensitivity. This approach
can overcome the conventional cantilever size limit of an AFM to achieve high bandwidth with low spring constant.