EP1196805A1 - Guide d'ondes plan integre et son procede de fabrication - Google Patents

Guide d'ondes plan integre et son procede de fabrication

Info

Publication number
EP1196805A1
EP1196805A1 EP00929323A EP00929323A EP1196805A1 EP 1196805 A1 EP1196805 A1 EP 1196805A1 EP 00929323 A EP00929323 A EP 00929323A EP 00929323 A EP00929323 A EP 00929323A EP 1196805 A1 EP1196805 A1 EP 1196805A1
Authority
EP
European Patent Office
Prior art keywords
substrate
applying
optical waveguide
flap
front side
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00929323A
Other languages
German (de)
English (en)
Inventor
Kent Erik Mattsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NKT Research Center AS
Original Assignee
NKT Research Center AS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NKT Research Center AS filed Critical NKT Research Center AS
Publication of EP1196805A1 publication Critical patent/EP1196805A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/27—Optical coupling means with polarisation selective and adjusting means
    • G02B6/2706—Optical coupling means with polarisation selective and adjusting means as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/105—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type having optical polarisation effects
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/12004—Combinations of two or more optical elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/126—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind using polarisation effects
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/27—Optical coupling means with polarisation selective and adjusting means
    • G02B6/2753—Optical coupling means with polarisation selective and adjusting means characterised by their function or use, i.e. of the complete device
    • G02B6/2766—Manipulating the plane of polarisation from one input polarisation to another output polarisation, e.g. polarisation rotators, linear to circular polarisation converters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
    • G02B6/29395—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device configurable, e.g. tunable or reconfigurable
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12035—Materials
    • G02B2006/12038—Glass (SiO2 based materials)
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12133—Functions
    • G02B2006/12142—Modulator
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12133—Functions
    • G02B2006/12157—Isolator
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B2006/12166—Manufacturing methods
    • G02B2006/12176—Etching
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/35—Optical coupling means having switching means
    • G02B6/3594—Characterised by additional functional means, e.g. means for variably attenuating or branching or means for switching differently polarized beams

Definitions

  • the invention relates to an integrated planar waveguide for transmitting electromagnetic radiation, wherein the light is propagated in the longitudinal direction of the planar optical waveguide, and comprising a section for changing polarization state.
  • the invention moreover relates to a method of manufacturing an integrated planar waveguide for transmitting electromagnetic radiation and comprising a section for changing polarization state.
  • Optical planar waveguides for changing the polarization state of light are well-known. These are produced e.g. by affecting the material of which the waveguide is made by electrical or magnetic fields. This is possible only for crystalline materials. Other methods use acoustic or thermal signals which act through the photoelastic effect. Here, crystalline as well as amorphous materials may be used.
  • the anisotropic effects that can be achieved in the above-mentioned elements by using external signals are modest, and relatively long extents are therefore required to achieve effective interaction between the external field and the light in the guide.
  • 10 mm - 20 mm waveguides are required.
  • the object of the invention is to make it possible to achieve a controlled interaction between the light and a strongly anisotropically designed waveguide, allowing a complete change in the polarization state to be achieved.
  • the object of the invention is achieved in that the section for changing polarization state is independently rotatable about the direction of light propagation rela- tively to the waveguide in general. It should be mentioned in this connection that typically at least two 50 - 100 ⁇ m long sections are required to achieve the complete change in the polarization state.
  • the rotatable waveguide may be formed such that at least two different directions of polarization exhibit different longitudinal coefficients of propagation. This may e.g. be done by forming the waveguide with a rectangular cross-section, there being a difference between the longitudinal coefficients of propagation of the TE and TM wave types. A great difference in the longitudinal coefficients of propagation may also be achieved by introducing thin layers of material with a high index of refraction on one or two opposite sides of a waveguide of rectangular or square cross-section. Another possibility is to place a thin high index layer in the centre of waveguide core. In these cases, the thin layers give rise to internal stress in the structure. This stress occurs because of the difference in thermal coefficients of expansion of the thin layers and the surrounding glass.
  • the rotatable waveguide may be formed such as to allow transmission of only one direc- tion of polarization.
  • This may e.g. be embodied by applying a metal layer or other absorbing material to one of the cross-sectional sides of the waveguide.
  • the absorbing layer may e.g. be applied to the rotatable section by a lift-off technique.
  • the actuator mechanism consists of at least one flap with a sheet on whose upper side the section for changing polarization state is mounted.
  • the flap is formed as an electrode which is provided with an insulating film on its underside, and which, together with a gold electrode on a glass substrate, causes the flap to move.
  • the flap is formed in a silicon substrate.
  • this will exhibit electrical conductivity r i may hereby be used directly as an electrode.
  • the waveguide contains several sections which may be rotated individually. This may e.g. be for a single compensator, where at least two sections are arranged in series along an axis which is parallel with the direction of light propagation.
  • PMD polarization mode dispersion
  • WDM wavelength division multiplexing signal
  • At least two sections are rotated 45° relatively to each other about a common axis defined by the direction of light propagation.
  • the invention also relates to a method.
  • This method is defined in claim 10 and is characterized by comprising the steps of:
  • the actual rota- tion of the waveguide section is achieved by twisting the waveguide cross-section in the transition between sheet and substrate.
  • Such a structure will require a relatively long transitional member between substrate and sheet to allow significant rotation of the member without causing ruptures in it.
  • claim 11 provides an expedient method of manufacturing a rotary bearing for the structure. This rotary bearing is manufactured by replacing item a) in the method defined in claim 10 by a method comprising the steps of:
  • the sacrificial layer is formed in amorphous or polycrystalline silicon or in silicon nitride.
  • the requirement to be met by the sacrificial layer is that it must be capable of resisting the etch of glass core and cladding, while being removable without the glass core and cladding being etched.
  • fig. 1 schematically shows the basic principle of the in- vention
  • fig. 2 shows the structure of a component with a planar optical waveguide with controllable rotation
  • fig. 3 is a cross-sectional view of the component of fig. 2 in a first working position
  • fig. 4 shows the component of fig. 3 in a second working position
  • figs 5a) - 5f) show the method of manufacturing a rotary bearing.
  • la, lb designate planar waveguides which have a common axis along which the light propagates.
  • a section 2 is interposed between the two planar waveguides, intended for changing the polarization state, which may e.g. be the direction of polarization of a wave (not shown) from the left-hand side of the figure in the pla- nar waveguide la to the planar waveguide lb shown at the right-hand side of the figure, or vice versa.
  • the section 2 is separated from the planar waveguides la, lb and can thus rotate about its axis, without the planar waveguides being affected by physical forces.
  • the method of manufacturing rotary bearings for such a structure will be explained more fully in connection with fig. 5.
  • two transitional members will be provided between the section 2 and the planar waveguides la and lb. These transitional members, designated 5a and 5b in fig. 2, are subjected to a twisting which does not give rise to any significant double refraction and is thus without importance to the optical function of the component. These transitional members, however, are of importance in connection with the size of the component.
  • the section 2 may be designed with a polarizing or double-refracting effect.
  • the section has a core which is surrounded by a cladding.
  • the principle of waveguide effect may be total internal reflection or reflection against a photonic crystal structure.
  • the size of the core may be dimensioned for both single mode and multimode wave propagation.
  • the section 2 is shown as a double-refracting section 3 with a core which has a rectangular cross-section and is incorporated in a rotating mechanism, as will be explained more fully below, cf. also figs. 3 and 4, where, however, the section 3 is shown with a core of square cross-section.
  • an optical waveguide of glass is formed with a core 11 and a cladding 10.
  • a mask is applied to the opposite side of the silicon substrate 7, and then a sheet 4 is provided by etching.
  • a further mask covering the sheet is applied, following which a flap 6 is provided in extension of the sheet 4 by etching.
  • a further mask is applied to the front side of the silicon substrate, and etching is carried out, following which the entire sheet 4 and parts of the flap 6 are released from the silicon substrate, as shown at 12 and 13 in fig. 3.
  • An insulating film is applied to the underside of the flap, which may be done e.g. by a thermal oxidation of the silicon substrate.
  • An electrode part preferably of gold 9, is deposited on a glass substrate 8.
  • the silicon substrate 7 and the glass substrate 8 are joined at the locations shown by the reference numerals 14, 15 and 16 in fig. 3.
  • a lower glass cladding 20 and a first glass core 21 are applied to the front side of the substrate.
  • a mask is applied to the front side of the substrate, and a part of the core is formed by an etch 22.
  • a sacrificial layer is applied to the front side of the substrate 23, and a second mask is applied to the front side of the substrate, and a part of the sacrificial layer is removed by an etch.
  • a second glass core is applied to the front side, and a third mask is applied to the front side, fol- lowing which the last part of the core is formed by an etch 24.
  • the glass core is heat treated to achieve a rounded profile for the rotary member, following which another sacrificial layer is applied to the front side 25.
  • a fourth mask is applied to the front side, and excess sacrifice layer is removed by an etch.
  • An upper glass cladding is applied to the front side of the substrate 26.
  • the rotary bearing is released during the same etch as releases the sheet 4 and the flap, as outlined in fig. 5f) .
  • sheet and flap are released by a glass etch, which is then followed by an etch of the sacrificial layer.
  • the rotary bearing consists of a short piece of glass core 24 which is embedded in the glass claddings 20 and 26.
  • a polarization controller if combined with a plurality of the same sections in series along an axis which is parallel with the direction of light propagation, makes it possible to provide a polarization controller .
  • two separate half- wave and quarter-wave sections are combined to an integrated system, in which the individual optical axes may be rotated ⁇ 45° independently of each other.
  • the rotation of ⁇ 45° is achieved by attaching an actuator mechanism to each side of a waveguide section.
  • Another embodiment with a smaller rotation of the optical axes may be achieved by increasing the nu ber of sections, which must alternately exhibit a positive and a negative phase delay and be rotated to the right and to the left, respectively, relatively to the direction of light propagation.
  • a variable analyzer may be manufactured by arranging a polarizer as the rotatable wave guiding section. Rotation of the polarizer produces a variable analyzer.
  • An optical insulator may be manufactured by arranging a quarter-wave section between two polarizers, the axes of these having been rotated 45° mutually.
  • the optical insulator is manufactured by applying to the first waveguide section a metal layer which attenuates the propagation of the TM wave type, so that just the TE wave type is transmitted through the first section.
  • the TE wave is the linear polarization state which oscillates in the plane of the substrate.
  • the second section is formed so as to give rise to a phase delay of ⁇ /2, and such that the optical axis is rotated 45° relatively to the plane of the substrate. After the second section, the light will be linearly polarized with a direction rotated 45° relatively to the output of the first section.
  • the axis of the polarizer in the third section has likewise been rotated 45° relatively to the axis of the first section, thereby allowing unobstructed passage of the light through it in the guiding direction.
  • Passage of section 3 means that the light is linearly polarized with a rotation of 45° relatively to the plane of the substrate. This light is rotated another 45° by passage through section 2, following which it is linearly polarized in a direction rotated 90° relatively to the plane of the substrate. This corresponds to a pure TM wave. This polarization state is attenuated by passage of the first section, whereby no light passes through section 1 in the blocking direction.
  • An optical modulator may be provided by combining a polarization controller, as described above, with a polar- izer. By switching between e.g. the TE wave type and the TM wave type, only the TE wave type will be transmitted through a polarizer with an axis in the TE direction.
  • a polarization-sensitive directional coupler may be used in another embodiment.
  • a further example of a modulator is two polarizers which are rotated independently to the right and to the left, respectively. Passage of light is allowed when their axes are parallel, while the light is extinguished when their axes are perpendicular to each other.
  • This modulator may also be used as a variable optical attenuator.
  • the waveguide core is interrupted at the two bearings between the waveguide sections, it will be necessary to add a material which adapts the indices of refraction between the sections such that no reflections occur at these transitions.
  • This material might e.g. be an oil with an index of refraction which corresponds to the index of the glass cladding.
  • Another possibility of sup- pressing reflections at the rotary bearing is to terminate it with an angled face toward the waveguide or to form the bearing with a tip toward the waveguide.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Optical Integrated Circuits (AREA)

Abstract

L'invention concerne un guide d'onde otique intégré, ainsi que son procédé de fabrication, dans lequel une section permettant de modifier l'état de polarisation est formée en tant qu'unité rotative indépendante. La rotation s'effectue par le positionnement de la section indépendante sur un mécanisme d'actionnement, constitué d'un volet pourvu d'une feuille (4) sur le côté supérieur de laquelle est fixée ladite section. Le guide d'ondes intégré est constitué d'un substrat de silicium (7), ce qui permet au volet d'être librement mobile. Le côté inférieur du volet (6) forme une électrode coopérant avec une électrode en or formée sur un substrat en verre (8), ces électrodes constituant le parties mobiles du mécanisme d'actionnement. Lorsqu'on applique une tension entre ces électrodes, le guide d'ondes intégré va tourner autour de l'axe défini par la direction de propagation de la lumière. Dans un mode de réalisation, le guide d'ondes intégré possède plusieurs sections. L'invention porte sur un régulateur de polarisation, permettant de réguler les états de polarisations souhaités dans un guide d'ondes optique, tel qu'une fibre optique. L'invention concerne également un compensateur intégré s'utilisant pour une compensation de premier ordre de la dispersion de polarisation de mode (PMD) dans un système de multiplexage par répartition en longueur d'onde (WDM).
EP00929323A 1999-05-27 2000-05-25 Guide d'ondes plan integre et son procede de fabrication Withdrawn EP1196805A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DK990679 1999-05-27
DKPA199900679 1999-05-27
PCT/DK2000/000280 WO2000073838A1 (fr) 1999-05-27 2000-05-25 Guide d'ondes plan integre et son procede de fabrication

Publications (1)

Publication Number Publication Date
EP1196805A1 true EP1196805A1 (fr) 2002-04-17

Family

ID=8096305

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00929323A Withdrawn EP1196805A1 (fr) 1999-05-27 2000-05-25 Guide d'ondes plan integre et son procede de fabrication

Country Status (4)

Country Link
EP (1) EP1196805A1 (fr)
AU (1) AU4745100A (fr)
CA (1) CA2375096A1 (fr)
WO (1) WO2000073838A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6879743B2 (en) * 2001-12-19 2005-04-12 Intel Corporation Crystal-core fiber mode converter for low-loss polarization-insensitive planar lightwave circuits
FI129419B (en) 2019-05-07 2022-02-15 Teknologian Tutkimuskeskus Vtt Oy Polarization selector
EP4083670A1 (fr) * 2021-04-30 2022-11-02 Nokia Solutions and Networks Oy Circuits de guides d'ondes optiques ayant des noyaux de guides d'ondes inclinés latéralement

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2443512A1 (de) * 1974-09-11 1976-03-25 Siemens Ag Hybrider wellenleiterkoppler und verfahren zu dessen herstellung
KR100241660B1 (ko) * 1997-05-22 2000-03-02 서원석 광섬유 편광 조절장치

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0073838A1 *

Also Published As

Publication number Publication date
WO2000073838A1 (fr) 2000-12-07
AU4745100A (en) 2000-12-18
CA2375096A1 (fr) 2000-12-07

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