CN1776476A

CN1776476A - Electrostatic Charpy Interferometric Light Modulator

Info

Publication number: CN1776476A
Application number: CN 200510057391
Authority: CN
Inventors: 黄尚廉; 张洁; 张智海; 韩磊; 闫许; 伍艺
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2005-11-18
Filing date: 2005-11-18
Publication date: 2006-05-24
Anticipated expiration: 2025-11-18
Also published as: CN100362387C

Abstract

The modulator is composed of substrate, control circuit, low electrodes layer, simply supported beam, movable reflector and fixed glass plate. Being formed on the substrate, low electrodes layer is contacted to control ends of each electrode in control circuit. The simply supported beam and support anchor are formed on the insulating layer, which is deposited on the low electrodes layer. Array of movable reflector is supported by the support anchor. The said array and the low electrodes layer constitutes parallel plate condenser with variable gap. There is certain gap between the fixed glass plate and the movable reflector. Shape of aircraft wing is adopted in the beam in order to reduce topographic effect and increase flatness of surface of movable reflector. Vertical up/down motion of the movable reflector happens under action of electrostatic force. Thus, the modulator modulates phase of light to realize switching state. Features are: quick response and simple structure.

Description

Electrostatic cimple-beam interference light modulator

Technical field

The present invention relates to a kind of spatial light modulation device, in particular, the present invention is a kind of by distance between static driven change glass plate and the moving reflector, make incident light by the time optical path difference change, utilize the interference of light principle to realize static interference light modulator to the incident light modulation.

Background technology

Prior art discloses the multiple photomodulator based on MEMS technology that can use separately or use with other modulators, and these modulators comprise digital micro-mirror device (DMD) and grating light valve (GLV) etc.

DMD is up to a million the modulators that deflectable reflection micro mirror constitutes by the manufacturing of MEMS technology.Total light extraction efficiency of DMD image device improves greatly, and modulating speed is fast, and contrast, brightness and homogeneity are all very outstanding, and the image of the close clearance order projection of micro mirror produces finer seamless picture, and it is not high to analyze Z-TEK.But still there is complex manufacturing process in it, the shortcoming that yields is low.

GLV is that the movable grizzly bar in a series of intervals constitutes, and it is to utilize the optical grating diffraction principle to realize the light signal modulation, and its manufacturing process is simple, and response speed is faster, and control circuit is simple, the yield rate height.Its shortcoming is: cannot say for sure to demonstrate,prove the grizzly bar that constitutes grating and be in the same plane; Gap affects diffraction efficiency between the grizzly bar; Real useful area is too little on the removable slit, and therefore single elemental area is big, makes GLV only be fit to do linear array, must add optical scanning mechanism and just can be used for optical imaging system.

Summary of the invention

Low for the useful area of the shortcoming that overcomes the DMD complex process and GLV, as to be difficult to be integrated into face battle array shortcoming, the object of the present invention is to provide a kind of electrostatic cimple-beam interference light modulator, free beam adopts the class wing shapes, can reduce orographic effect, increases the moving reflector surface smoothness.Adopt the interference of light principle that incident light is modulated, the technology of device is made simply, the yields height, modulating speed is fast, and optics effectively utilizes area big.

The technical solution adopted in the present invention is as follows:

The present invention discloses a kind of electrostatic cimple-beam interference light modulator, and it mainly comprises following structure:

1, substrate;

2, be manufactured on control circuit on the substrate;

3, the lower electrode layer that on substrate, forms, each cell electrode control end of lower electrode layer and control circuit contacts;

4, be deposited on insulation course on the lower electrode layer;

5, free beam that on insulation course, forms and support anchor, free beam adopts the class wing shapes;

6, be connected the moving reflector array that is supported on the support anchor, moving reflector array and lower electrode layer constitute the air chamber of gap variable, each moving reflector is by the top electrode that is connected to form between the free beam, and common ground, a pixel of a corresponding light modulator arrays of moving reflector, the corresponding photomodulator unit that forms of each moving reflector all can independently apply bias voltage, make moving reflector do vertical movement up and down, the flat board that constitutes phase variable is interfered device, forms the dot matrix of different interference effects;

7, cover the fixing glass flat board of all moving reflector tops by the bonding mode, four angles of fixing glass flat board are supported on the substrate, leave certain spacing between fixing glass flat board and the moving reflector, the dull and stereotyped upper and lower surface plated film of fixing glass is realized effective transmission and reflection.

Distance can change by the bottom electrode change in voltage between described fixed flat planar glass and the moving reflector, between not during making alive when being biased voltage V, incident light is π through the out-of-date phase differential that will form.

This photomodulator adopts static driven, its principle of work is: reflect on the glass plate surface when incident light incides device surface, transmitted light incides moving reflector behind glass plate simultaneously, through producing certain phase difference with reflected light behind the glass plate, the phase differential size is by the distance decision between glass plate and the movable reflecting surface, when phase differential is zero, light beam interferes long mutually, behind lens, form bright spot, and phase differential is when being π, light beam interferes mutually and disappears, and forms dim spot behind lens, thereby realizes incident light is carried out phase modulation (PM).

This optical modulation device can adopt the manufacturing of MEMS technology, and it and existing IC technology are compatible, at silicon chip higher slice structure device.

Advantage of the present invention is: device is a two-dimensional array, be used for need not to add optical scanning mechanism when image shows, therefore simplified optical system, because it is its simple double-decker, simple in structure, yields is high, can realize with general IC surface processing technique fully, solved the DMD complex process, the problem that yields is low adopts the static driven moving reflector simultaneously, modulating speed is fast, and simultaneously optics effectively utilizes area to compare GLV to improve a lot; The simple beam structure that adopts has adopted the structure of class wing, has improved the depth of parallelism of moving reflector.

This modulator can be widely used on high definition digital television, Projection Display, printer, optical communication, the spectrometer.

Description of drawings

Fig. 1: electrostatic cimple-beam interference light modulator structural drawing

Fig. 2: the partial structurtes figure that removes the electrostatic cimple-beam interference light modulator behind the fixing glass flat board

Fig. 3: the cellular construction figure that removes the electrostatic cimple-beam interference light modulator behind the fixing glass flat board

Fig. 4: the structural drawing after removing moving reflector on Fig. 4 basis

Fig. 5 A and Fig. 5 B: the sectional view of electrostatic cimple-beam interference light modulator list pixel under the different operating state

Fig. 6: during the light beam oblique incidence, electrostatic cimple-beam interference light modulator is based on the shear interference optical schematic diagram

Fig. 7: during light beam normal incidence, electrostatic cimple-beam interference light modulator is based on the shear interference optical schematic diagram

Among the figure, 1 substrate; 2 lower electrode layers; 3 insulation courses; The gap of 4 free beams and bottom electrode; 5 free beams; 6 support anchor; 7 moving reflectors; 8 fixing glass flat boards

Embodiment

The invention will be further described below in conjunction with the drawings and specific embodiments:

Referring to Fig. 1, Fig. 3 and Fig. 4, the manufacturing process of this modulator is as follows: production control circuit on substrate 1, splash-proofing sputtering metal and photoetching thereon forms lower electrode layer 2, each cell electrode control end of lower electrode layer 2 and control circuit contacts, the certain thickness insulation course 3 of deposit, splash-proofing sputtering metal aluminium forms the free beam 5 of class wing shapes and supports anchor 6, supporting deposit formation moving reflector 7 on the anchor again, the fixing glass flat board 8 (can be stationary mirror again) that will be coated with semi-permeable diaphragm at lower surface covers moving reflector 7 tops by the mode of bonding at last, four angles of fixing glass flat board 8 are supported on the substrate 1, dull and stereotyped 8 lower surfaces of fixing glass and moving reflector 7 spacings make incident light by the back from fixing glass planar surface reflected light and by the moving reflector reflection again between fixing glass flat board transmitted light phase differential be π.

By Fig. 2 as seen, a pixel of each moving reflector 7 respective devices, all moving reflectors 7 are whole as public top electrode by being connected to form between the free beam 5, but each moving reflector 7 can realize independently moving up and down, and control the light and shade attitude of this pixel.

Fig. 5 A and Fig. 5 B are the change in location situations of the moving reflector 7 of device under the different operating state, among the figure, and h ₁Be electrostatic cimple-beam interference light modulator list pixel in dark attitude be distance between fixing glass flat board and the moving reflector; h ₂Be electrostatic cimple-beam interference light modulator list pixel in bright attitude be distance between fixing glass flat board and the moving reflector; V is the voltage that drives the moving reflector motion.When bottom electrode does not apply voltage, incident light impinges perpendicularly on device array, because from the light of fixing glass flat board 8 reflection with have the optical path difference of odd-multiple half-wavelength from the light of moving reflector 7 reflections, be that phase differential is n π (n=1,3,5 ...), disappear by interfering mutually after dull and stereotyped 8 outgoing of fixing glass, correspond to the dark attitude of device this moment; And after bottom electrode applied suitable voltage, phase differential was zero, and is long mutually by interfering after dull and stereotyped 8 outgoing of fixing glass, corresponds to the bright attitude of device this moment; Vertical movement up and down takes place to the phase modulation (PM) of incident light in moving reflector 7 under the effect of electrostatic force, realize the switch attitude of light, when the light beam oblique incidence its optical schematic diagram as shown in Figure 6, incident beam A is through twice refraction and primary event, P point outgoing from figure, be light beam A ', incident beam B is through primary event, the also outgoing of P point, i.e. light beam B ' from figure, light beam A ' and B, the P point interferes again; H represents the distance between the fixing glass flat board and moving reflector in the electrostatic cimple-beam interference light modulator list pixel.When the oblique normal incidence of light beam, its optical schematic diagram as shown in Figure 7, incident beam A reflects at upper surface, P from figure ₁Point outgoing, i.e. light beam A '; Incident beam A is through twice refraction, and primary event is also from the outgoing of P point, i.e. light beam A ", light beam A so ' and A " P in the drawings ₁Point interferes.Same principle, light beam B ' and B " in the drawings P ₂Point interferes.Change by distance h realizes that the phase appearance of interfering disappears.(dotted line of Fig. 7 is just in order clearly to see the path of light, and in fact incident light, reflected light, refract light do not have horizontal displacement)

Bias voltage among the present invention applies and adopts this area existing mature technology, adopts driven more.According to different array requests, adopt active driving or passive drive mode.The electrode outlet line of driving circuit can obtain when making this structure simultaneously.

Invention has been described more than to adopt example.But those those skilled in the art have read become after the disclosure file open-and-shut improvement and modification, still belong to the application's spirit and category.

Claims

1. An electrostatic simply supported beam interferometric light modulator, characterized in that it comprises:

a. Substrate;

b. control circuitry fabricated on the substrate;

c. The lower electrode layer is formed on the substrate, and the lower electrode layer is in contact with the electrode control terminals of each unit of the control circuit;

d. an insulating layer deposited over the lower electrode layer;

e. Simply supported beams and support anchors formed above the insulation;

f. The movable mirror array connected and supported on the support anchor, the movable mirror array and the lower electrode layer form an air cavity with variable spacing, and each movable mirror forms an upper electrode through the connection between simply supported beams, and a common ground, one movable mirror corresponds to one pixel of the light modulator array, and each movable mirror corresponds to the optical modulator unit formed by independently applying a bias voltage, so that the movable mirror can move vertically up and down, forming a phase adjustable Variable flat-panel interference devices to form lattices with different interference effects;

g. The fixed glass plate covered above the movable reflector by bonding, the four corners of the fixed glass plate are supported on the substrate, there is a gap between the fixed glass plate and the movable reflector, and the upper and lower surfaces of the fixed glass plate coating to achieve efficient transmission and reflection.

2. The light modulator according to claim 1, characterized in that: the distance between the fixed glass plate and the movable mirror can be changed by changing the voltage of the lower electrode, and when no voltage is applied between the two, it is the same as when a bias is applied When the voltage is V, the phase difference formed when the incident light passes is π.

3. The light modulator according to claim 1, wherein the movable mirror is electrostatically driven.

4. The optical modulator according to claim 1, wherein the simply supported beam adopts a wing-like shape.