CN1304873C

CN1304873C - Arm beam type flash raster optical modulator and array

Info

Publication number: CN1304873C
Application number: CNB2005100201849A
Authority: CN
Inventors: 黄尚廉; 张洁; 付红桥; 闫许; 张智海; 伍艺
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2005-01-13
Filing date: 2005-01-13
Publication date: 2007-03-14
Anticipated expiration: 2025-01-13
Also published as: CN1658008A

Abstract

The present invention relates to a cantilever beam type flash grating light modulator and an array. The cantilever beam type flash grating light modulator is provided with a base and an electric driver, wherein a lower electrode layer and an insulating layer are orderly formed on the base, a plurality of belts with reflecting surfaces are suspended above the insulating layer, a gap is retained between the insulating layer and each belt, each belt is supported on the insulating layer through one end of the belt, and meanwhile, a metallic aluminium film on each belt forms an upper electrode which is used as a light reflection layer so as to form a cantilever beam type structure on the whole; the belts are arranged in parallel according to the row positions so as to form an area array, and all the belts are almost on the same plane in the free state. All reflection planes can be kept on a first plane when a bias voltage is exerted on cantilever beam type flash grating light modulator; when all the components are positioned on the first plane, a diffraction grating reflects incident light beams; when the preset belts are positioned at a preset slope angle, the diffraction grating diffracts the incident light beams, and then, the flash grating of the present invention flashes the light energy to a preset diffraction order.

Description

Arm beam type flash raster optical modulator and array

Technical field:

The present invention relates to a kind of beam modulation device.More particularly, the present invention relates to a kind of arm beam type flash raster optical modulator, it has the reflecting surface that is essentially the plane, and this surface has selectively distortion, so that blazed diffraction grating to be provided.

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 then 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 a kind of typical low-light mechanical system, is used for the Primary Component of photoswitch, optical attenuator and high-definition television etc.The GLV device is by diffraction effect light beam to be played the effect of switch or decay, rather than adopts direct reflection or Polarization Modulation.To be that structure is a plurality of on silica-based be suspended in suprabasil parallel micro stripline things with this device, and these ribbons have electric coupling, and when a voltage was provided for it, movable ribbon was basad bending, thereby formed good diffraction grating.The light valve array of diffraction grating specifically comprises delegation's aligning parallel to each other, separates, elongated reflection part movably, each movably reflection part all can be parallel and the plane that separates in independently move with respect to the fixation reflex parts.Movably and fixing reflection part so dispose, make corresponding removable and the fixation reflex parts cause light incident thereon to take place to reflect under different states together or (with) diffraction.When side-play amount is the odd-multiple of λ/4, produce the phase differential of the odd-multiple of pi/2 via the incident beam of different ribbon reflection, therefore the one-level at diffraction image obtains largest light intensity; When side-play amount is the even-multiple of λ/2, produce the phase differential of the even-multiple of π via the incident beam of different ribbon reflection, therefore the zero level at diffraction image obtains largest light intensity, so just reaches the purpose of beam modulation.

The problem that above-mentioned GLV exists is as follows:

(1) if incident light wave is not accurately to be λ, so so-called black pixel will show certain light tone, and so-called bright pixel can't show light tone completely.Therefore compare relatively poor with notional result based on the getable contrast of demonstration of above-mentioned principle.

(2) in the time of must guaranteeing not apply voltage as far as possible, be that device is in OFF state, grizzly bar is in the same plane, reach the purpose that reflects incident light fully, otherwise,, also will form grating if grizzly bar is not in the same plane, will produce us and not wish the diffraction light that obtains, reduce device contrast of display degree; And when applying bias voltage, promptly device is in ON state, must guarantee that again the movable grizzly bar in the pixel all drops to sustained height, and these making precision and technologies to device have all proposed very high requirement.

(3) because there are a gap w in structure and process limitations between two grizzly bars _g, this gap will influence grating diffration efficient.

(4) for to obtain suitable skew and bigger effective diffraction area, the length of grizzly bar should be about 100 microns, and like this, this device can only be used for linear array, when being used to show, need can't form the face battle array structure as DMD by mechanical scanning.

Summary of the invention

Problems at the prior art existence, the object of the present invention is to provide a kind of arm beam type flash raster optical modulator and array, enlarge the useful area of device, realize the face battle array structure of modulator, improve the optical diffraction efficient of device, simplify the processing technology of device.

Goal of the invention of the present invention realizes by the following technical solutions:

The arm beam type flash raster optical modulator of the present invention's design has following structure, it has a substrate and an electric driver, be formed with insulation course and electrode layer in the substrate successively, above electrode layer, be suspended with a plurality of ribbons with reflecting surface, leave the gap between electrode layer and the ribbon, these ribbons by separately an end portion supports in substrate, form the beam type structure, ribbon is arranged in juxtaposition by the ranks position, formation face battle array, all ribbons are basic coplane when free state.Under electricity drives, the suspension end of all ribbons will be biased to support rim, form blazed grating.

When device was not applied to voltage, all ribbons all were positioned at primary importance, and device is in the OFF attitude, sees Fig. 3, and diffraction grating is with beam reflection, and most concentration of energy is at 0 grade.When by apply suitable bias voltage between electrode layer and ribbon, electrostatic force will make the ribbon of these suspensions be out of shape downwards, because it is the beam type structure, so all downward-sloping equal angular of all suspension ribbons, forming a blazing angle is θ _bBlazed grating, ribbon is positioned at the second place, device is in the ON attitude, see Fig. 4, this moment, device had the effect of diffraction to incident light, according to diffraction theory, most luminous energy will concentrate on the level inferior upward (being generally 1 grade) that design needs, and so just reach the modulating action to light.

The advantage that the present invention is compared with prior art had is as follows:

(1) owing to adopt the principle of blazed grating, ideally can make luminous energy all concentrate on 1 grade;

(2) owing to adopt cantilever beam structure, the technology of making is fairly simple;

(3) by electrode layer being applied suitable bias voltage, and the effect of support rim, all reflecting surfaces can be remained under the predetermined angle of inclination, can under predetermined receiving angle, obtain high diffraction efficiency so;

(4) under the condition that guarantees enough rigidity, can increase the area that glitters, relative useful area is bigger than grating light valve, forms the face battle array easily;

Description of drawings

Fig. 1 is the tomograph of the arm beam type flash raster optical modulator that proposes of the present invention;

Fig. 2 is the technological process that the present invention proposes;

Fig. 3 is a photomodulator shown in Figure 1 view in " OFF " attitude;

Fig. 4 is a photomodulator shown in Figure 1 view in " ON " attitude;

Fig. 5 is the diffraction efficiency distribution figure of two states;

Fig. 6 is the synoptic diagram that the arm beam type flash raster optical modulator that proposes of the present invention forms the face battle array.

Embodiment

Referring to Fig. 1,2, arm beam type flash raster optical modulator has following composition structure: a substrate 21 and an electric driver 200, be formed with lower electrode layer 22 and insulation course 23 in the substrate successively, above insulation course, be suspended with a plurality of ribbons with cantilever beam structure 25 with reflecting surface, leave the gap between insulation course 23 and the ribbon 25, these ribbons 25 in substrate, form the beam type structure by separately an end portion supports.Driving circuit 200 connects upper and lower electrode by circuit, and driving circuit 200 adopts this area existing mature technology, adopts driven more.According to different array requests, adopt parallel or driven in series mode.The electrode outlet line of driving circuit can obtain when making this structure simultaneously.When the driving circuit among Fig. 1 200 when applying suitable bias voltage, ribbon 25 keeps horizontal coplane; When 200 voltages that applied were particular bias voltage, ribbon formed blazed grating with deflection.Ribbon is arranged in juxtaposition by the ranks position, formation face battle array.

Said structure obtains by following technology:

1. be substrate 21 at silicon substrate, the aluminium of deposit layer of metal thereon is as lower electrode layer 22;

2. deposit one deck SiO ₂As electric insulation layer 23;

3. mask etch forms support rim 24;

4. deposit one deck sacrifice layer, sacrificial layer material is PSG, the mask etch sacrifice layer, and deposit layer of metal aluminium film forms top electrode, also as reflection layer;

5. mask etching forms cantilever beam structure 25;

6. releasing sacrificial layer obtains total.

The photomodulator of said structure is not when applying voltage, and its ribbon 25 is suspended from the end, keeps coplane.By the upper/lower electrode layer is applied suitable bias voltage, and the effect of support rim 24, make all reflecting surfaces can remain on predetermined tilt angle theta _bDown.(the OFF attitude, Fig. 3), the light of incident will all be reflected when all ribbons all are positioned at first plane.(the ON attitude, Fig. 4), when promptly having identical angle of inclination, diffraction grating will make light beam generation diffraction, the energy of the overwhelming majority is diffracted into the level that needs time go up (general 1 grade), as shown in Figure 5 when these ribbons are positioned at the second place.That is to say that when the time spent of doing that structure plays catoptron, used light all is reflected back, and diffraction does not take place, most energy all concentrates on 0 grade.When structure is in " ON " attitude, it will play the effect of diffraction grating, by each parameter value of design photomodulator, and can be so that energy all focuses on certain one-level of needing time.

The face battle array structure that this arm beam type flash raster optical modulator forms as shown in Figure 6.

Claims

1, arm beam type flash raster optical modulator, it has a substrate and an electric driver, be formed with lower electrode layer and insulation course in the substrate successively, it is characterized in that: above insulation course, be suspended with a plurality of ribbons with reflecting surface, leave the gap between insulation course and the ribbon, these ribbons by separately an end portion supports on insulation course, layer of metal aluminium film on the ribbon forms top electrode simultaneously, also as reflection layer, whole formation beam type structure, ribbon is arranged in juxtaposition by the ranks position, formation face battle array, all ribbons are basic coplane when free state, under electricity drives, the suspension end of all ribbons will be biased to support rim, form blazed grating.

2, arm beam type flash raster optical modulator according to claim 1 is characterized in that: substrate is provided with the support rim of a plurality of height unanimities, the suspension end of respectively corresponding each the beam type ribbon of these support rims.

3, a kind of arm beam type flash raster optical modulator array is characterized in that using a plurality of claims 1 or 2 described photomodulators to become array by rows, and each photomodulator can independently apply bias voltage, forms the different dot matrix of diffracting effect.

4, a kind of arm beam type flash raster optical modulator array, it is characterized in that using a plurality of claims 1 or 2 described photomodulators to be arranged in the face row by row and column, each photomodulator can independently apply bias voltage, can form the different dot matrix of diffracting effect on a face.