Optical filters containing resonant waveguide gratings are designed and fabricated using low-loss, robust materials. The double-layer filters contain a silicon dioxide diffractive element on a hafnium dioxide waveguide deposited on a fused silica substrate. Noise-pattern formation is minimized by use of an antireflective absorption layer during holographic grating recording in photoresist. Subsequent fabrication steps include metallization, lift-off, and oxygen plasma etch to create a metal etch mask for final CF4 plasma etching of a surface-relief grating. Spectral characterization with a tunable laser shows that the resulting filter exhibits 90% efficiency, 1.2 nm linewidth, and low sidebands.

No abstract

No abstract

Experimental results on resonantly excited second-harmonic generation (SHG) in a periodic ionically self-assembled monolayer (ISAM) film are reported. A double-layer guided-mode resonance filter (GMRF) structure is coated with 40 bilayers of pyrlium-based chi(2) ISAM thin film and excited with the fundamental of a Nd:YAG laser. Enhanced second-harmonic conversion in the ISAM film is achieved because of the local field enhancement associated with the fundamental resonating leaky mode. This method of SHG is particularly promising, as the ISAM films under investigation exhibit anomalous dispersion that may be applied for phase matching to improve nonlinear conversion efficiency.

No abstract

No abstract

A method for producing stabilized interference patterns for ultraviolet interference lithography using a CCD camera as the detector element is described. Intensity data obtained from the CCD element are filtered in software to minimize speckle and detector noise effects as well as to determine the relative phase of the interfering beams. A control signal is then issued to correct the fringe drift. The system allows rapid reconfiguration of the lithography setup with minimum realignment of optical components.

In order to connecting villages in rural area with a city, a hybrid optical communication is proposed. The Optical fiber communications that are implemented as a backbone on the Palapa Ring network has an opportunity to be expanded to reach rural area through the implementation of free-space optical communications (FSO) as the optical relaying networks (ORN). The major problem of FSO as the ORN is turbulence effects induce an optical propagation. In this research, FSO as the ORN implements novel technique to improve the performance of hybrid FSO where the amplification of signal is produced through serial configuration of optical amplifiers in cascaded meanwhile to reduce the noise in the end of receiver, optical band pass filter is implemented. The simulation of hybrid FSO is performed in Optisystem 7.0 where ORN is implemented in two nodes. The length of optical fiber connection to FSO is set to be constant at 75 km. The range of optical propagation in FSO is set at 1–9.4 m. The results of simulation show that at the range of 1–8 Km of optical propagation under atmospheric turbulence, range values for SNR and BER are achieved at 46.23–26.61 dB and 6.7x10-17–1.5x10-6, respectively.