Micromechanical Tunable Optical Filter

A micromachined vertical cavity tunable filter with AlGaAs/GaAs distributed Bragg reflector is presented. This filter can be electrostatic tuning over a range of 28nm with an applied voltage of 7V.

1.3μm Si-Based MOEMS Optical Tunable Filter with a Tuning Range of 90nm

Optical filters capable of single control parameter-based wide tuning are implemented and studied. A prototype surface micromachined 1.3μm Si-based MOEMS (micro-opto-electro-mechanical-systems) tunable filter exhibits a continuous and large tuning range of 90 nm at 50 V tuning voltage. The filter can be integrated with Si-based photodetector in a low-cost component for coarse wavelength division multiplexing systems operating in the 1.3μm band.

1.55μm Fabry-Perot Thermo-Optical Tunable Filter with amorphous-Si as Cavity

A 1.55μm Fabry-Perot (F-P) thermo-optical tunable filter is fabricated. The cavity is made of amorphous silicon (a-Si) layer grown by electron-beam evaporation technique. Due to the excellent thermo-optical property of a-Si, the refractive index of the F-P cavity will be changed by heating; the transmittance resonant peak will therefore shift substantially. The measured tuning range is 12nm, FWHM (full-width-at-half-maximum) of the transmission peak is 9nm, and heating efficiency is 0.1K/mW. The large FWHM is mainly due to the non-ideal coating deposition and mirror undulation. Possible improvements to increase the efficiency of heating are suggested.

Fabrication of 1.3 mu m Si-based MEMS tunable optical filter

In this paper we report the fabrication of 1.3 mum Si-based MEMS tunable optical filter, by surface micromaching. Through wet etching of polyimide sacrificial layer, a tunable Fabry-Perot filter was successfully fabricated. We make the capacitance measurement of the prototype device, compare the experimental curve with the theoretical one, and explain the difference between them.

Bandpass filter by a stretch and double-exposure technique

We fabricated a bandpass filter based on Moire Bragg grating in fiber with a uniform phase mask We employed a stretch and two-exposure technique, in which the fiber was exposed to UV light from a KrF excimer through a phase mask and then the fiber is stretched and given another exposure at the same region. Due to the stretch, the periods of these two grating are slightly different, and there is a transmission between two reflection peaks at the Bragg wavelength of these two gratings.Applying different stretch can control the bandpass width of the filter. We measured the stretch characterization of a uniform Bragg grating and found the Bragg wavelength of the grating shifts linearly with the stretched length.We theoretically analyzed the grating structure and its reflection spectrum. The filter's characteristics can be optimized by choosing appropriate parameters. We will give a theoretical discussion concerning which parameters and how they affect the filter's operation.