TWI247928B - Tunable liquid crystal integrated optic device - Google Patents

Abstract

The present invention relates to a tunable liquid crystal integrated optic device, which can be used in filter, coupler and optic add-drop multiplexer, which comprises a liquid crystal layer serving as an active covering layer, first and second waveguide elements containing optic grating and distributed in a ridge like fashion through the liquid crystal layer, an isolation layer that cooperates with a substrate to interposed the liquid crystal layer from upper and lower sides thereof, and two electrode layers connected to a power source to induce a potential, whereby by applying an external potential to control the axial direction of the liquid crystal, the equivalent refractivity of the waveguides can be tuned in accordance with the variation of the electrical field to realize simple structure, easy manufacturing, low costs, and integratability.

Description

1247928 • V. INSTRUCTION DESCRIPTION (1) "" [Technical Field] The present invention relates to a tunable liquid crystal integrated optical component that can be applied to filters, couplers, and optical complement/multiplex multiplexers, especially A liquid crystal layer is used as an active coating, and a first waveguide element and a second waveguide element having a grating extending in a ridge shape are arranged on the liquid crystal layer, and a second waveguide element is arranged to match the substrate, and the liquid crystal layer is sandwiched up and down. An isolation layer, and two electrode layers for connecting a power source to generate a voltage, and controlling the axial direction of the liquid crystal by an applied voltage, so that the equivalent refractive index of the waveguide changes with a modulation electric field, thereby achieving a simplified structure and being easy to manufacture. Those who reduce costs and can be integrated. [Prior Art] Optical Add-Drop Multiplexers (0ADM) are indispensable components in the Dense Wavelength Division Multiplexe (MDM) and can be used in the network. On the node, multiple wavelengths of uplink and downlink via the node are processed to simplify the architecture of the network device. With the continuous increase in the number of Internet users in the future, there will be higher demand for bandwidth and routing speed, and the introduction of various network application services will also drive the network toward a higher scheduling flexibility. In addition to the increase in transmission speed and distance, the new generation network must also be transparent to various signals and provide dynamic configuration of bandwidth. Based on this concept, the next-generation network needs to combine MM system and adjustable component technology to provide a flexible, reliable and stable network. In order to increase the number of wavelengths in each fiber of the DWDM system, the design of the germanium tends to be complicated, and it is more required to accommodate more wavelength processing capabilities.

1247928 V. INSTRUCTIONS (2) The demand and practicality of this adjustable optical multiplexer (Tunable OADM) will be increasingly expanded. So far, many optical wavelength-compensation multiplex technologies have been published, such as Array Waveguide Grating (AWG) and optical switches (TO Switches), and the Marc-Zander interferometer. Bragg grating-assisted Mach-Zehnder Interferometer-based OADM (Reference: !\£『(1 jealous 311,1\人.81:^8861', elbow.八 Milbrodt, EJ Laskowski, CH Henry, GE Kohnke, '丨Integrated-optical Mach-Zehnder odd-drop filter fabricated by a using UV-induced grating exposure, "Appl· Opt·,ν〇1·36,pp· 7838-7845, 1 997·), Acoustic-Optic Tunable Filter (OADM), and Fiber Bragg OADM based on Bragg fiber grating (References: A·S·Kewitsch, G·Α·Rakuljic, PA ffillems, and A. Yariv, "All-fiber zero-insertion-loss add-drop filter for wavelength-division multiplexing,丨丨Opt· Lett. ,

Vol· 23, No. 2, pp·1 06-1 08, Jan·1 998·). The tunable OADM is available on the market today (references: Ρ· Tang, 0· Eknoyan, and Η·F· Taylor, 丨丨Rapidly tunable optical add-drop multiplexer (OADM) Using a static-strain-induced grating in

1247928 V. Description of invention (3)

LiNb03, f丨 J· Lightwave Technol·, Vol· 21, No· 1

Jan·2003·) is mostly implemented with item components, and requires the addition of an electronic circuit (Circulator). The overall structure is complicated, which may cause the module or system to be bulky and expensive. The fiber-optic multiplexer (fiber grating 0ADM) modulates the grating period by elastic expansion or temperature change, which has a long adjustment time and a slow modulation speed; the sound and light adjustable chopper gas-light compensation multiplexer (A0TF) ) The polarization sensitivity is low, although the E0TF changes the sensitivity of the A0TF, but the wavelength bandwidth is larger, but it is the disadvantage that the a〇tf II E0TF is difficult to overcome. SUMMARY OF THE INVENTION The main object of the present invention is to provide a liquid crystal type adjustable integrated optical element with simplified structure, capacity, low cost, and integration, which is applied to a filter, a coupler, and a light compensation/capture The main body may include a substrate, and a layer as an active coating is disposed on the substrate, and a grating diode element and a second waveguide element are arranged in the liquid crystal layer to extend through the ridge. For matching with the substrate: an isolation layer that bridges the liquid crystal layer, and two for connecting a power source to produce a sandwich electrode layer, and controlling the liquid crystal crystal axis by an applied voltage to adjust the refractive index of the wave voltage Variation in electric field. Equivalent [Embodiment] Please refer to the first figure, the liquid crystal adjustable element of the present invention can be applied to filters, couplers, and optical complement/occupation x body light main systems. Including a ceremonial device, a substrate (10);

Page 8 1247928 • V. Description of the Invention (4) A liquid crystal layer (2 0 ) for modulation and as an active cladding; a waveguide element group (30) including a first waveguide element (32) and a first a second waveguide element (31) having a grating (320), and the first waveguide element (32) and the second waveguide element (31) extend in a ridge structure a liquid crystal layer (20); an isolation layer (40) 'for clamping the liquid crystal layer (20) with the substrate (1); and two electrode layers for connecting a power source to generate a voltage (5) 〇) (51), mainly disposed outside the liquid crystal layer (20) as an interlayer or the isolation layer (4 〇) and the substrate (10) outside as an interlayer. In the implementation of the invention, the second waveguide element (31) may also have a grating (310). In a preferred embodiment of the present invention, the two electrode layers (50) (51) for connecting a power source to generate a voltage, an electrode layer (5 〇) is disposed on the bottom surface of the substrate (10) and the other electrode layer (51) is disposed on the top surface of the isolation layer (4〇). In a preferred embodiment of the invention, a spacer (60) Cspaeei can be provided outside the barrier layer (4〇). In a preferred embodiment of the present invention, the substrate (10), the isolation layer (40), and the second waveguide element (32) (31) may be a semiconductor, an inorganic crystal, a quartz, a metal, a glass, or a dielectric. It is made of an electric or high molecular material (p〇lymerK such as PMMA). In a preferred embodiment of the invention, the electrode layer (50) (51) can be made of any material that can form an electrode, such as indium tin oxide transparent electrode (ITO) glass.

Page 9 1247928

V. DESCRIPTION OF THE INVENTION (5) In a preferred embodiment of the present invention, please refer to Appendix I, which is a design parameter of the component of the present invention, that is, the thickness of the substrate (1〇) is 15 // m, refractive index (Refractive index) is 1.49 'The thickness of the first waveguide element (31) is 4//m, and the width (W idth ) is 5 //m 'refractive" (refractive" nde X) 1.52, the first waveguide element (32) has a thickness of 4/zm, a width of 3 //in 'refractive index of 1.51, and an index modulation of 5. 5χ. 10-3; the thickness of the spacer layer (40) is 1 〇, and the refractive index is 1 · 3 〇 The theory of the present invention may be due to the shape, symmetry, and grating of the first and second waveguide elements. The position of the present invention is changed. In the practical operation, for the analysis of the grating coupler, the present invention adopts the more accurate mode coupled modal waveguide theory of D·Marcuse, and the structure designed in the embodiment, Only consider the consumables in a single transverse electric field transverse-electri Both the slanting and backward modalities of c(TE). The field distribution of the single mode waveguide and the grating waveguide is calculated as shown in the third figure. In the case of the second waveguide, the electric field of the grating waveguide is: cos^Aj-0,2)exp[-r,+ 5)], +5) '+^ + /3⁄4)-^2], +s + h2) <x<-(hl+s) cos(0l2)exp[7#2+s + h2)]f x<-(hl+s + h2) propagation in the first and second waveguide elements The light field can be decomposed into two forward and backward modes, wherein the second waveguide element has a periodic index grating (peri〇dic grating)

Page 10 1247928 V. INSTRUCTIONS (6) Consideration must be given to the coupled coupling; otherwise the first waveguide component is not. The equation of the coupler can be expressed as: = + sink 21 t (Ul) small 2 + 1 which (a '2AZ) 々 1 + into 21 [- do 2 + A) Z] forbear 2 Pu = / [12exp [z(ft -+ +,·[12®Φ[-,(Α +Α)ζ]^ι + ίΧΐ2®Φ(-(10)22〇^^ = -iKx, &φ {αβιζ)Αι - iK2l ©φ [ί{β2 + ft )ζ]Α2 - iKx ΧΒΧ - iK2X exp [- ι{β2 - ^ )z]^2 = -^i2€3φ[ι(Α + )52)z]4 -iK22 exp (ί2β2ζ Α2 - ϊΧ12 exp[- ί(βχ - β2)ζ]^ -/a: 22^2 is illustrated in a preferred embodiment of the present invention, as shown in the fifth figure, let L be the length of the waveguide, start The condition is 4(8)(1)=〇, and the modes on the 7th and 3L pieces (32)(31) are modal p and modal β respectively, and the combination coefficient is that it has a close relationship with the disturbance coefficient Δ. The coupling coefficient is ~(2)=f £ Δεν〆(3)' (JC) The method of the present invention still utilizes the equivalent refractive index, and the equivalent refractive index results obtained by the two-dimensional and three-beam propagation methods are only about 0122% different. "After the simulation, the two-dimensional beam propagation method is used. If you want to be more refined, you can multiply the length of the splitter obtained by the simulation by the calibration parameter of i.0012207. When the liquid crystal is subjected to an applied electric field, it is easily changed by the polarizability, and the coupler waveguide can be adjusted to achieve the selected wavelength. Η羊改1247928 V. Invention description (7) The fourth figure is a negative type Schematic diagram of the refractive index ellipsoid of a single optical axis crystal, S is the incident light direction, assuming that the liquid crystal is rotated by the applied electric field, the equivalent refractive index is ne{e) - τ - yjn / co ^ e + nj1 sin2e , For the refractive index of ordinary ray, Ile refers to the refractive index of extraordinary ray. Please refer to the fifth figure for a schematic diagram of the operation of the embodiment of the present invention. Table 1. When the modality enters the second waveguide element (31) (WG Π ) without grating, the penetration strength in length L is Τ1 = 2·6798*10-3, Τ2 = 9·2569*1 0 -5, and the reflection intensity is 1Π=5·1598*10-2, R2 = 9.4562*10-1. The component is completely unbiased, ie the refractive index of the liquid crystal is 1.485, and its spectrum is as shown in the sixth figure. County test 7 (10) can take the first strong wave length of the second wave in the first wave of the guide element (32) (WGI), that is, R2 = 0.9471. When the voltage is controlled When the refractive index of the liquid crystal is 1 485 1497, there is still good strength, and the operation frequency control is 32 5 ± 8 GHz. The wavelength of the multiplexer of the embodiment of the present invention can be adjusted between 1 549.15 and 1551. Therefore, the structure of the present invention is simplified, and it has the effect of being easy to carry out, inexpensive, and integrable. The above description is a preferred embodiment of the present invention, and the change in the concept of the present invention is not affected by the function of θ and the spirit not covered by the figure. Within, it is given to Chen Ming. The target circumference of I / 3 In summary, the invention has a simplified structure and is easy to manufacture.

1247928

Page 13 1247928 Brief Description of the Drawings ------ (1) Schematic Part: The first drawing is a sectional view of the structure of the present invention. The second drawing is a schematic sectional view of the structure of the embodiment of the present invention. The third figure is a schematic diagram of a modality of an embodiment of the present invention. The fourth figure is a schematic diagram of the refractive index ellipsoid of the present invention. The fifth figure is a schematic diagram of the operation and parameters of the embodiment of the present invention. The sixth figure is a design parameter value of the embodiment of the spectrum of the liquid crystal having the refractive index of the liquid crystal of 实施.485 according to the embodiment of the present invention. π. Table 1 is a waveguide of the substrate (30) of the invention (2) Component group (3 1 0 ) (320) grating (50) (51) electrode layer (20) liquid crystal layer (31) (32) waveguide _ (40) isolation layer (60) spacer

Claims (1)

♦(·································································································· And a light complementing/taking multiplexer comprising: a substrate; a liquid crystal layer for modulating the active cladding; a waveguide element group including the first waveguide component and a second waveguide component, The first waveguide element has a grating, and the first waveguide element and the second waveguide element extend in a ridge shape through the liquid crystal layer; an isolation layer is configured to cooperate with the substrate to sandwich the liquid crystal #· and 曰曰θ ' φ Two electrode layers for connecting a power source to generate a voltage, which are mainly disposed outside the liquid crystal layer as an interlayer or the isolation layer and the substrate as a loss layer. A tunable liquid crystal integrated optical element as described in claim 1, wherein the second waveguide element has a grating. The tunable liquid crystal integrated optical body 疋=, wherein the two electrode layers for connecting a power source to generate a voltage, ^. The electrode layer is disposed on the bottom surface of the substrate, and the other electrode layer is disposed on the side of the isolation layer. The adjustable liquid crystal integrated optical component described in claim 1 is provided with a spacer outside the isolation layer ( Spacer). </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; Page 15 1247928 t No. 93103136 Λ_η 曰 , VI. Patent scope ---- Element 7,.; Adjustable liquid crystal integrated optical as described in Item 1 of Shen Zhongwei. Further, the substrate may be an inorganic crystal. Element 8, two please: = In the adjustable liquid crystal integrated optical device according to Item 1, the substrate may be quartz. Element 9, m: The tunable liquid crystal integrated optical device of the above item 1, wherein the substrate is glass. Element 10·Λ申\Special use of the adjustable liquid crystal integrated optical body described in the first item can be made of polymer material (Polymer). The component, the basin is made of a tunable liquid crystal integrated optical body as described in Item 1 of the above-mentioned article. The second and second waveguide elements can be made of a semiconductor. The adjustable liquid crystal integrated optical gossip first and second waveguide elements can be made of metal. Yuanzhu, Ganzi ^ The adjustable liquid crystal integrated optical body described in the first item of the patent range 1 4 , 忒 first, The two waveguide elements may be made of an inorganic crystal. The tunable liquid crystal integrated optics described in the first item of the patent scope, in the eighth, the first and second waveguide elements may be made of a dielectric material. The first and second waveguide elements may be made of a polymer material, as described in the above-mentioned patent scope. The first and second waveguide elements may be made of a polymer material. The adjustable integrated optical element 'where the electrode layer is made of a material capable of forming an electrode. 1 7 · The adjustable integrated optical element 'in the electrode layer' as described in claim 16 Made of indium tin oxide transparent electrode (IT〇) glass 1247928 Case No. 9310313R • VI. Scope of Application for Patent 曰 Amendment 1 8 • As described in item 1 of the scope of application for patents, the isolation layer can be made of semiconductors and can be learned first. The adjustable integrated optical element, the 'isolation layer' can be made of inorganic crystal. = The tunable integrated optical element /, wherein the isolation layer is made of a dielectric material as described in claim 1. 1. In the tunable integrated optical element 22 of claim 1, the spacer layer may be made of a polymer material. The adjustable integrated optical element as described in claim 1 of the patent application scope has a thickness of 15 /zm and a refractive index (Refractive index 疋ι·49; the thickness of the first waveguide element is * The width is 3 "111', the refractive index is 1.51, the index modulation is 5·5χ 10-3; the thickness of the second waveguide element is 4 //m 'the width is 5 /zm, The refractive index is 1.52; the thickness of the spacer is 10 //m and the refractive index is 1.3. Page 17