Publicação
Development of a MEMS actuator for optical modulation enabling enhanced photonic sensing
| Resumo: | Silicon mechanical photonic wavelength converter (MPWC) has been investigated aiming at the need for all-silicon photodetectors in the infrared spectrum. All-silicon photodetectors have the advantage of low cost micromachining but suffer from low efficiency and poor resolution (high noise levels), being unsuitable for wavelengths larger than 1 um. The operation of a MPWC requires high-frequency modulation, in the order of 1MHz, of a light beam over a few hundred microns. Herein, a new MEMS (microelectromechanical system) actuator is proposed for integration into the MPWC. It consists of an interferometer in which the incident input light is modulated at a temporal fre quency matched to the mechanic resonance of nanorods in the reference beam waveguide and relies on the resonance of the nanorods due to optical gradient force. The challenge is fabricating a MEMS shut ter/actuator with high enough operating frequencies and enough displacement amplitude. High-frequency MEMS resonators exist but with limited displacements. This works reports the development of a MEMS optical modulator with a grate shape to decrease the displacement amplitude required to modulate a 100x100 µm2 beam area (necessary for application). Given the trade-off between resonance frequency and displacement amplitude typical of MEMS optical shutters, the challenge lies in having micrometre displacements at such a high frequency. MEMS design focused on minimizing movable mass, minimizing damping, and tuning the spring stiffness to set the resonance frequency at 500 kHz. The design includes 2 µm pitch grating (100x100 µm2 ) on a support frame with metal sputtered on top, four springs and either parallel-plate or comb drive actuation electrodes. The fabricated devices’ experimental in-plane displacement and resonance frequency were measured by stroboscopic video microscopy on a Polytec MSA-500. The device was set in an acrylic chamber, and the results were extracted at atmospheric pressure and low vacuum. At low vacuum pressure, the quality factor increases and maximum displacement amplitudes are achieved. |
|---|---|
| Autores principais: | Pires, Inês Eduarda Alves |
| Assunto: | High-frequency Optical Modulator MEMS Displacement Frequência Ótico Modulador Deslocamento |
| Ano: | 2023 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Silicon mechanical photonic wavelength converter (MPWC) has been investigated aiming at the need for all-silicon photodetectors in the infrared spectrum. All-silicon photodetectors have the advantage of low cost micromachining but suffer from low efficiency and poor resolution (high noise levels), being unsuitable for wavelengths larger than 1 um. The operation of a MPWC requires high-frequency modulation, in the order of 1MHz, of a light beam over a few hundred microns. Herein, a new MEMS (microelectromechanical system) actuator is proposed for integration into the MPWC. It consists of an interferometer in which the incident input light is modulated at a temporal fre quency matched to the mechanic resonance of nanorods in the reference beam waveguide and relies on the resonance of the nanorods due to optical gradient force. The challenge is fabricating a MEMS shut ter/actuator with high enough operating frequencies and enough displacement amplitude. High-frequency MEMS resonators exist but with limited displacements. This works reports the development of a MEMS optical modulator with a grate shape to decrease the displacement amplitude required to modulate a 100x100 µm2 beam area (necessary for application). Given the trade-off between resonance frequency and displacement amplitude typical of MEMS optical shutters, the challenge lies in having micrometre displacements at such a high frequency. MEMS design focused on minimizing movable mass, minimizing damping, and tuning the spring stiffness to set the resonance frequency at 500 kHz. The design includes 2 µm pitch grating (100x100 µm2 ) on a support frame with metal sputtered on top, four springs and either parallel-plate or comb drive actuation electrodes. The fabricated devices’ experimental in-plane displacement and resonance frequency were measured by stroboscopic video microscopy on a Polytec MSA-500. The device was set in an acrylic chamber, and the results were extracted at atmospheric pressure and low vacuum. At low vacuum pressure, the quality factor increases and maximum displacement amplitudes are achieved. |
|---|