Bistable mirror translational grating light modulator and its array driven by sma

Abstract

The invention relates to the technical field of a light modulator and specifically relates to a raster light modulator, a manufacturing method and an array thereof. The SMA (shape-memory alloy)-driven bistable reflector translation type raster light modulator comprises the following components: a substrate, an insulation layer on the substrate, a movable flat plate which is disposed above the insulation layer, is supported by a support beam, is provided with a reflection plane and is driven by bias applied to support beams to perform vertical motion up and down, the support beams and a fixation raster, wherein the central portions of beam bodies are connected with the movable flat plate, the beam bodies are made of an SMA, and the fixation raster covers a structure unit composed of the aforementioned parts. According to the invention, the SMA is utilized, the material can be deformed to a preset shape after electrical heating, a bistable characteristic is formed, the purposes of reducing position shifting caused by faster unstable state position residence and preventing adherence failure are achieved, at the same time, the driving voltages are low, the demodulator can be compatible to a conventional digital chip drive circuit, the stroke is large, and the driving force is large.

Description

technical field [0001] The invention relates to the technical field of optical modulators, in particular to a grating optical modulator and an array thereof. Background technique [0002] MOEMS (Micro-Opto-Electro-Mechanical Systems) technology is a further fusion of MEMS (Micro-Electro-Mechanical Systems) technology and optical technology. The integration of circuits has the advantages of mass production, low unit cost, small size, fast response, and reliable performance. At present, optical modulators based on MOEMS technology have achieved high-speed development and wide application due to their excellent performance. Typical examples include the digital micromirror device DMD of Texas Instruments and the grating light valve GLV of Silicon Photonics. Projection display, adaptive optics, sensor, optical communication, and miniaturized optical platform have also been widely used. Using MOEMS technology to achieve more and wider functional development derived from the oper...

AI Technical Summary

Problems solved by technology

The grating light modulator based on MOEMS proposed by Chongqing University, using the principle of grating diffraction to realize optical modulation, has achieved fruitful research results in the application of projection technology, but the existing grating light modulator, such as the application number 200510020185. The mirror translational grating optical modulator disclosed in the Chinese invention patent has relatively high requirements for the control of the distance between the upper and lower reflective surfaces, and it is easy to form position drift with the fluctuation of the drive circuit voltage in the two positions of power off and power on, resulting in The spacing parameters of the upper and lower reflective surfaces are different from the design parameters, and the expected diffraction effect cannot be obtained

Especially in the case of applied voltage, the height at which the beam stays at the pull-down position is determined by the driving voltage, and if you want to keep the grating position suspended at a certain height when the pull-down is in the non-contact working mode, you must keep it constant. Applying a constant voltage requires high stability of the drive circuit, which increases the complexity of the drive circuit

In addition, in the long-term use process, when the electrostatic pull-down is excessive due to interference and causes the pull-in phenomenon, once the van der Waals force between the upper and lower surfaces of the translational grating optical modulator, the electrostatic force generated by the accumulation of trap charges and other surface forces exceed the cantilever Elastic recovery force, in the absence of other upward external pulling force, it is easy to cause adhesion so that the device can no longer bounce and fail

However, if the working mode of the device is changed so that the upper and lower surfaces of the translational grating light modulator are in contact during pull-down, although the device position is guaranteed to be stable without drift, it is more likely to cause device adhesion failure

On the other hand, in order to obtain a large stroke displacement by electrostatic drive, a higher drive voltage is usually required. In order to be compatible with the existing conventional digital chip drive circuit, the compromise method to reduce the drive voltage is to reduce the rigidity of the cantilever beam, which increases the fatigue. and the possibility of adhesion

[0003] Among the commonly used drives for MOEMS devices, electromagnetic drives and sparse-tooth drives are not suitable for grating optical modulators due to their large structures. Shape memory alloy SMA drives, compared with piezoelectric, electrostatic, and hot gas drive methods, have higher work density. It has the advantages of large recoverable strain, large deformation recovery stress, and low driving voltage, but when used in optical modulators, it must be designed comprehensively with the specific structure of the device to achieve good results. The starting point of this patent is to use the translational mirror The optical modulation characteristics of the vertical translation of the grating light modulator are organically combined with the stable bistable switching results of the shape memory of the SMA to solve the problem of working stability and adhesion failure of the grating light modulator

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