For certain applications, total internal reflection (TIR) lenses are potentially more effective compared with refractive lenses and reflection mirrors since they permit more light power to go through the optical system. The efficiency of such lenses becomes even more prominent for miniature systems application where light absorption has negligible effect compared with the reflection losses at the interfaces. However, at such scales, the effect of Goos-Hänchen shift that associates the TIR should be accounted for in order to design a proper surface profile of the TIR lenses. It has been shown that a useful design that determines the total internal reflective surface profile can be obtained by solving an ordinary differential equation; such results facilitate realizing effective macro- and micro-scale lenses that are highly useful in integrated optics circuits and miniature optical systems.
The waveguide second-harmonic generation is a reliable mechanism for frequency doubling of laser emission since light can be highly confined to a nonlinear waveguiding medium, besides being compatible with current present semiconductor and solid state lasers. An optimization is achieved based on designing the resonator mirror reflectivity at the fundamental and the second-harmonic wavelengths to obtain optimal trapping and optical losses of the fundamental and the second-harmonic waves inside the resonator.
Optical notch filtering is essential for many engineering applications. Optical resonant filters represent a useful alternative to achieve optical notch filtering. Designing these filters with optimal performance is significant because they can be a key component of important systems, such as optical communications, biophotonics applications, and optical sensors. The design is based on choosing the filter structural parameters optimally to achieve the best filtering properties, which are decided by the application. The filter parameters were chosen as the waveguide thickness and gratings depth. A new merit function was defined to measure the filtering properties and contained a degree of importance that ranges from zero to unity as an additional parameter in order to meet specifications. The optimization was realized systematically after simple parameters' decoupling, which was based on practical considerations. A numerical example was considered, and simulations with results were presented for complete clarification of the work. Optimizing the performance of optical resonant filters to meet the system specifications is significant and useful because it contribute to a wide range of applications that depend on optical notch filtering.
Optical resonant filters represent an important alternative to achieve optical notch filtering. Enhancing the filtering properties by new designs for these filters is an essential aspect because they can be a key component in important systems, such as optical communications, bio-photonics applications, and optical sensors. The proposed designs depend on a multilayer waveguide that can function as a confining medium and an antireflection coating as well, which are not achieved simultaneously by a single-layer waveguide. Zeroing the Fresnel reflection, which is the background reflection in the reflection spectra of the optical resonant filter, is highly desirable for better filtering properties.