Infrared Micro-Optoelectronic Devices Based On MEMS Technology

The world has seen a tremendous development in the modern science and technology in the last few decades, and urgently need the photoelectronic system to be more miaturized, light weighted, integrated and compact. The emergence of MEMS technology, which is one of the revolutionary technolgies of the last century, provides a nearly perfect solution to these demands. This dissertation is mainly devoted to study two kinds of micro optoelectronic devices based on MEMS technology, both theoretically and experimentally. One of these two kinds of optoelectronic devices is a passive optical device:dual-band micro filter array, and the other is an active device:narrowband infrared thermal emitter. In this thesis, in-depth and systematical studies about these two kinds of devices have been conducted. The main contents and achievements of the thesis are summarized below:(1) Visible/infrared dual-band micro filter arrayA visible and infrared dual-band microfilter array has been designed and fabricated. It has been integrated with the PtSi CCD to construct a dual-band imaging system. Thin-film absorbing filter design method has been adopted to design the infrard pass filter to reject the light from visible to near infrared spectral region. Thin-film reflecting filter design method has been used to design the visible passband filter to eliminate the difficulties of suppressing the multiple high-order reflectance bands. For the fabricating process, a novel double layer T-shape structure has been devised to strip the thick infrared passband filter (about 5μm), and it is easy to fabricate and compitable with the high temperature (about 350℃) deposition process of optical thin film. The fabricated microfilter array has met with the technical requirements and has been integrated with Pt/Si CCD chip by flip-chip bonding. Visible and infrared imaging has been achieved successfully using this hybrid integrated device.(2) Narrowband thermal emitter based on one-dimensional photonic crystalsOne kinds of narrowband infrared emitter based on one-dimentional photonic crystals has been designed. Its emission spectrum is very narrow, ranging from several to several tens of nanometer, and the emittance is near 100%. The radiative characteristics of the narrowband infrared emitter, including emittance, central wavelength, spectral width and spectral-directional emittance of the device, have been investigated theoretically. To solve the thermal stress problem of this kind of emitter, we have proposed to use a vacuum resonant cavity to seperate the one-dimensional dielectric photonic device and the high temperature metal layer. Besides, the vacuum cavity also introduce another degree of freedom, one can modify the emission spectrum by changing the cavity length. Tunable and scannable infrared thermal source could be achieved use this configuration, further broaden the applications of this kind infrared thermal emitter.(3) Narrowband thermal emitter based on one-dimensional metal/insulator/metal heterostructure gratingOne kind of narrowband infrared emitter based on one-dimensional metal/insulator/metal heterostructure grating has been designed. Its radiative characteristics differs from the ordinary narrowband thermal emitter based on one-dimensional grating fabricated on metals (e.g. Ag, Au) or polar materials (e.g. SiC), as it can support both TM and TE polarizations. The central wavelengths of the different polarizations can be designed differently, so this structure can be designed as a biwavelength light source, which is very useful in the gas sensing application. In this structure, the dielectric layer only exists between the metal layers. The modal field is mainly confined in dielectric layer; the quality factor is much higher, so the emission spectrum is one order narrower than the reported results. Besides, the emission spectrum of this emitter does not change too much when varying the emitting angle.(4) Narrowband thermal emitter based on microstrip antenna structureA microstrip antenna like narrowband thermal emitter has been investigated theoretically. The relation between the central wavelength and the structure parameters has been obtained by combining with the confinement of the transverse wave vector (due to the lateral confinement of the electromagnetic field) and the dispersion relation of the metal/insulator/metal waveguide structure. We have simulated this kind of emitter by FDTD and found that its spectral width is very narrow and the radiative characteristic is almost the same within a broad range of emission directions. Omnidirectional narrowband thermal emitter and omnidirectional perfect selective absorber can be realized by this configuration, which has very important applications in the infrared detecting field.(5) Design, FEM simulation and fabrication of the narrowband infrared thermal emitter based on MEMS technologyMEMS microhotplate, as a key platform for narrowband infrared emitter, has been designed and analysized by finite element method (FEM) for the multiphysics coupling field. The key properties of the microhotplate, such as temperature and stress distribution, deformation and dynamical response, have been obtained. Besides, a low thermal deformation microhotplate has been proposed for the narrowband thermal emitter based on one-dimensional photonic crystals, to ensure that the device is still working when it is heated up.Two kinds of narrowband infrared emitters based on surface plasmon and microstrip antenna structure have been fabricated by MEMS technology. The fabricating processes have been designed and optimized. Several processes have been investigated; especially the anistropic wet etching process of silicon for forming isolated structure. Wet etching apparatus and protective clamp have been designed. Finally, the narrowband thermal emitter has been fabricated. The infrared radiative spectrum test system has been set up and calibrated by blackbody. The emission sepectrum of the fabricated emitter has been tested and the narrow emission characteristics have been demonstrated.