A proposal for wide range wavelength switching process using optical force

Optomechanical wavelength up-conversion based on optical force and core-shell scattering effects are used to control light coupling between two waveguides. This system consists of two parallel optical waveguides with 20 µm lengths suspended on a silica substrate embedded with Ag/Si/SiO2 core-shell nanoparticles. By mid-IR plane wave illumination with different intensities and different wavelengths on nanoparticles, scattering would increase and result in an improvement in attractive gradient optical force exerted on waveguides. Via bending waveguides toward each other, visible light propagating in the first waveguide would couple to another. PDMS as a polymer is used to reduce the required power for bending waveguides. Results reveal that when waveguides’ gap equilibrium is 400 nm and wavelengths of control and probe lights are 4.5 µm and 0.45 µm respectively, about 10.75 mW/µm2 power is needed to bend waveguides for total coupling of light between waveguides. The efficiency of the coupled waveguides system is %43.

Optical lattice with spin-dependent sub-wavelength barriers

We analyze a tripod atom light coupling scheme characterized by two dark states playing the role of quasi-spin states. It is demonstrated that by properly configuring the coupling laser fields, one can create a lattice with spin-dependent sub-wavelength barriers. This allows to flexibly alter the atomic motion ranging from atomic dynamics in the effective brick-wall type lattice to free motion of atoms in one dark state and a tight binding lattice with a twice smaller periodicity for atoms in the other dark state. Between the two regimes, the spectrum undergoes significant changes controlled by the laser fields. The tripod lattice can be produced using current experimental techniques. The use of the tripod scheme to create a lattice of degenerate dark states opens new possibilities for spin ordering and symmetry breaking.

Large-Area and Ultrathin MEMS Mirror Using Silicon Micro Rim

A large-area and ultrathin MEMS (microelectromechanical system) mirror can provide efficient light-coupling, a large scanning area, and high energy efficiency for actuation. However, the ultrathin mirror is significantly vulnerable to diverse film deformation due to residual thin film stresses, so that high flatness of the mirror is hardly achieved. Here, we report a MEMS mirror of large-area and ultrathin membrane with high flatness by using the silicon rim microstructure (SRM). The ultrathin MEMS mirror with SRM (SRM-mirror) consists of aluminum (Al) deposited silicon nitride membrane, bimorph actuator, and the SRM. The SRM is simply fabricated underneath the silicon nitride membrane, and thus effectively inhibits the tensile stress relaxation of the membrane. As a result, the membrane has high flatness of 10.6 m−1 film curvature at minimum without any deformation. The electrothermal actuation of the SRM-mirror shows large tilting angles from 15° to −45° depending on the applied DC voltage of 0~4 VDC, preserving high flatness of the tilting membrane. This stable and statically actuated SRM-mirror spurs diverse micro-optic applications such as optical sensing, beam alignment, or optical switching.