Abstract. The obtainable quality factor for a nano beam resonator is limited due to internal damping such as thermoelastic damping. Therefore, understanding how internal damping varies with the respective resonant modes is very important to design a high performance nanoresonator. In this research, we investigate thermoelastic damping depending on vibration modes of nano beam resonators using finite element method. The study results show that the quality factor of a nanoresonator is lower than at high order modes. The silicon nano beam resonator with the quality factor larger than one million can be achieved by optimizing the dimensions of the resonant beam.

We theoretically study the dynamics of an atomic force microscope cantilever under various irradiation configurations of a laser. By conveying a stream of photons and its momenta, the laser beam whose geometrical intensity profile has a Gaussian form will exert a nonuniform radiation pressure on the cantilever surface and modify its vibration. The dependences of cantilever modeshapes on the laser spot position and waist reveal a possibility of diminishing or exciting a specific eigenmode. For cantilevers of ∼200 µm length, the vibration amplitude of higher-order eigenmodes can be increased 4–5 times. This implies the change in cantilever effective mass once the interaction with the ambient is taken into account. The study gives a deeper understanding of soft cantilever dynamics in liquids and can be applied in the modern measurement configuration where high frequencies are required.

In this paper, we propose and investigate the modal characteristics of wedge surface plasmon polariton (SPP) waveguides for guiding surface plasmon waves. The wedge SPP waveguides are composed of a silver layer deposited onto the surface of a wedge-shaped silicon dielectric waveguide. The wedge-shaped silicon dielectric waveguides are explored from the anisotropic wet etching property of single crystal silicon. The wedge SPP waveguides are embedded in a dielectric medium to form the metal–dielectric interface for guiding the surface plasmon waves. The propagation characteristics of the wedge SPP waveguides at the optical telecommunication wavelength of 1.55 μm are evaluated by a numerical simulation. The influence of the physical parameters such as the dimensions of the wedge SPP waveguide and the refractive index of the dielectric medium on the propagation of the surface plasmon wave is investigated. In addition, by comparing the propagation characteristics, we derive the wedge SPP waveguide with the optimal performance.

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For a vibration system, the best designed spring is compliant to a desired vibration mode while it is robust to other undesired modes. There are several types of spring design for displacing the proofmass along the x and y axes, however, very few designs of spring compliant to the z axis are introduced. Therefore, we propose a z axis microactuator in which the suspending spring is designed so that it is only compliant to vibration along the z axis. The suspending spring consists of straight beam stages mechanically coupled with each other via frames which are symmetrically designed around a center plate. The operation characteristics of the microactuator is investigated by theoretical expresses and numerical simulation. The frequency split between the z axis mode and undesired modes can obtain more than 45%. The operation frequency can be modified in a wide range, from 68 kHz to 400 kHz, by changing the dimensional parameters of spring beams. The spring beams can be lengthened to increase displacement in the z axis while the mode cross-talk is still suppressed. Compared to the previously reported researches, the current microactuator shows robustness to undesired vibration modes, which is potential for integration in low mode cross-talk multi-axis micro-stages and low-noise mechanical sensors.