We present a direct patterning method of dielectric materials via temporally shaped femtosecond laser pulses. A thinfilm waveguide with a 2D periodic pattern of photonic crystals with circular base elements is investigated. We use dielectrics since they are transparent especially in the visible spectral range, but also in UV and near infrared range. Thus, they are very suitable as optical filters in the very same spectral region. Since structuring of non-conductive dielectric materials suffers from charging, the implementation of laser processing as patterning method instead of conventional processing techniques like electron beam lithography or focused ion beams is a very attractive alternative. Despite a low refractive index contrast, we show by numerical results that normal incident of light to the plane of periodicity couples to a waveguide mode and can excite Fano resonances. That makes the device extremely interesting as narrow-band optical filter. Applications of optical filters in the visible and UV range require fabrication of photonic crystal structures in the sub-100 nm range. Temporally shaped femtosecond laser pulses are applied as a novel method for very high precision laser processing of wide band gap materials to create photonic crystal structures in dielectrics. Shaping temporally asymmetric pulse trains enable the production of structures well below the diffraction limit.<sup>1 </sup>We combine this process with deposition of a high refractive index layer to achieve the targeted resonant waveguide structure. Additionally, we focus on the rim formation arising by laser processing since this is an important issue for fabrication of photonic crystal arrays with small lattice constants.
InP based tunable optical MEMS devices, such as Fabry-Perot filters, VCSELs, photodiodes, consist of two distributed
Bragg reflectors (DBRs) and a cavity. Tuning of the filter wavelength is achieved by electrostatic actuation of the two
DBRs which are p-doped and n-doped, respectively, and reversely biased. The cavity and the DBRs consist of a stress
compensated InP/airgap structure which is fabricated by sacrificial layer removal, using FeCl3 wet etching of InGaAs
layers. In this work we investigated the influence of p-and n-type conductivity on the etching process. We observed that
the sacrificial layer etch rate of n-InGaAs is 7 times slower than the p-InGaAs. This influences the stress in the n-DBR
section of the tunable device. Based on these results novel wavelength tunable optical devices with multiple InP
membrane/airgap structures will be designed.