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WO2003034115A2 - Hybridation laser - Google Patents

Hybridation laser Download PDF

Info

Publication number
WO2003034115A2
WO2003034115A2 PCT/GB2002/004692 GB0204692W WO03034115A2 WO 2003034115 A2 WO2003034115 A2 WO 2003034115A2 GB 0204692 W GB0204692 W GB 0204692W WO 03034115 A2 WO03034115 A2 WO 03034115A2
Authority
WO
WIPO (PCT)
Prior art keywords
waveguide
laser
alignment feature
layer
facet
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.)
Ceased
Application number
PCT/GB2002/004692
Other languages
English (en)
Other versions
WO2003034115A3 (fr
Inventor
John Hughes
Nicholas Parsons
Stephen Wood
Ian Flint
Paul Jerram
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.)
Lumentum Technology UK Ltd
Original Assignee
Bookham Technology PLC
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 Bookham Technology PLC filed Critical Bookham Technology PLC
Priority to AU2002334184A priority Critical patent/AU2002334184A1/en
Publication of WO2003034115A2 publication Critical patent/WO2003034115A2/fr
Publication of WO2003034115A3 publication Critical patent/WO2003034115A3/fr
Anticipated expiration legal-status Critical
Ceased 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
    • G02B6/42—Coupling light guides with opto-electronic 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
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
    • G02B6/4228—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements
    • G02B6/423—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements using guiding surfaces for the alignment
    • 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
    • G02B6/30—Optical coupling means for use between fibre and thin-film device
    • 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
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
    • G02B6/4228—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements
    • G02B6/4232—Passive alignment, i.e. without a detection of the degree of coupling or the position of the elements using the surface tension of fluid solder to align the elements, e.g. solder bump techniques

Definitions

  • This invention relates to semiconductor lasers, and in particular to the hybridisation of semiconductor lasers onto a wafer which supports a waveguide structure.
  • WO01/06285 a single mask is used to create the core glass and the alignment features. This is advantageous as it reduces the possibility of alignment errors.
  • the process disclosed requires the -alignment features, to be created in the top layer of the buffer glass. This approach is disadvantageous as it requires alignment features to be formed on top of a layer of etch stop. Etch stop . is not intended to have layers grown on it and the resultant ' features are not as well defined or as of high quality as would be preferred.
  • the chemicals used for the removal can attack and smooth the alignment features.
  • WO01/06285 provides for tolerances along the optical axis by providing bumps on the laser which butt against slightly tapered rails on the waveguide . As the angle of the taper is low, tolerance in the etching of the waveguide or the growth of the alignment features on the laser will be magnified by the taper angle.
  • the process relies on precision cleaving of the laser facet and precision alignment of the gold bumps on the laser which contribute to alignment errors.
  • the invention aims to overcome the disadvantages with the prior art arrangements and techniques outlined above.
  • the invention creates alignment features for the two critical axes in the core layer which are produced in the ' same operation as the waveguide. More specifically, there is provided a method of fabricating, a waveguide having a core layer deposited on a buffer layer arranged on a substrate, comprising forming a masking layer defining the waveguide and at least one component alignment feature, for aligning a component with the waveguide, on the core layer.
  • the invention also provides a waveguide comprising a substrate, a buffer layer arranged. on the substrate and a core layer deposited on the buffer layer, the core layer comprising waveguide features and at least one alignment feature for aligning a component with the waveguide.
  • Embodiments of the invention have the advantage that by forming the alignment features from the same masking layer and etch as the waveguide, the alignment features can be near perfectly aligned in two axes.
  • near perfect alignment in a third axis may be achieved by forming a further masking layer over protected alignment features, the mask overlapping the waveguide and defining a mechanical stop, and etching. This etch defines the waveguide facet which is therefore aligned with the mechanical stop.
  • the original alignment features can then be revealed by removing the protection.
  • the waveguide is a silica waveguide
  • the core layer is doped glass
  • the buffer is also glass.
  • a wide variety of components may be attached to a- waveguide embodying the invention.
  • the invention also provides a method of attaching a semiconductor laser to a waveguide, comprising fabricating the waveguide by the method according to the invention as defined above, forming an alignment feature on the laser and attaching the laser to the waveguide such that the alignment feature on the laser abuts the at least one alignment feature on the waveguide.
  • the invention also provides a semiconductor laser hybrid comprising a semiconductor laser attached to a waveguide according to the invention as defined above, the laser comprising an alignment feature abutting the at least one alignment feature ' on the waveguide.
  • the laser may include a mode expander or the waveguide end may include a lens.
  • the laser may be attached using solder bumps .
  • Figure 1 is a schematic view of a waveguide on a substrate
  • Figure 2 is a flow chart showing steps in the process of embodying the invention
  • Figure 3 shows schematically a waveguide section and alignment features
  • Figure 4 shows a plan of the components of Figure 3 with a pattern defined on the top of the cladding glass; and Figure 5 shows side and end views of a laser showing an attachment feature and a facet.
  • the following description describes the fabrication of a structure in a waveguide and the assembly of a laser onto the waveguide.
  • the structure of the waveguide is shown in
  • the waveguide 10 shown in Figure 1 is typically grown onto a silicon substrate 12.
  • the waveguide comprises a buffer or under clad layer 14, a core glass layer 16 and cladding or over clad 18.
  • the buffer layer 14 has a thickness of approximately 15 microns, the core layer 16 , a thickness of approximately 5 microns and the cladding 18, a thickness of approximately 15 microns.
  • the buffer, the core layer and the cladding are all typically made of silica glass.
  • the core layer is doped, typically with germanium (Ge) to increase its refractive index with respect to the buffer and cladding layers 14, 18 by between approximately 0.3 to 1.3%.
  • the buffer is first deposited on the silicon substrate (100 Fig. 2) .
  • the core glass is then deposited over the whole of the buffer glass (102 Fig. 2) usually by plasma enhanced
  • the waveguide structure is formed in the core layer by defining the structure in a layer of etch stop, such as polysilicon, which is deposited on the core glass (104 Fig. 2) .
  • etch stop such as polysilicon
  • the core glass is then dry etched away leaving the required waveguide features which were covered by etch stop. (106 Fig. 2) .
  • the alignment features in the waveguide are created in the core glass for two critical axes.
  • the alignment features are created in the same layer as the waveguide features and are produced in the same etch mask that defines the waveguide features.
  • the alignment features are nearly perfectly aligned with the waveguide.
  • Figure 3 shows a section of the waveguide 10 which includes a sacrificial end 20 which will be formed into a facet to couple to the laser.
  • a pair of alignment features 30 are provided which are used to align the semiconductor laser when it is mounted.
  • the alignment features 30 include a number of triangular projections 40 extending from one of the alignment features towards an opposite face of the other of the pair. These triangular projections abut a recessed edge of the laser and are intended to minimise the contact area with the laser to reduce stiction effects and remove the possibility of yield losses due to process problems. Other shaped projections could be used.
  • the polysilicon etch stop would be removed at . this stage.
  • the polysilicon above the alignment feature is protected (108 Fig. 2) and then the polysilicon removed from the rest of the structure (110 Fig.. 2 ) .
  • a cladding layer 18 (Fig. 1) is then grown onto the core ⁇ glass (112 Fig. 2) .
  • a pattern is defined on the top of the cladding glass which is aligned to the waveguide and the alignment features. This is shown at step 114 in Figure 2. .
  • the alignment of this pattern, which is shown by the dashed line 50 in Figure 4 is not critical except that it must overlap the waveguide in area and must overlie the alignment features.
  • the pattern is used to define a second etch stop mask which is used to protect all the area outside the pattern area. (Step 116 Fig. 2). That is, all the area outside the
  • a pair of mechanical stops 60 are defined which fix the gap between the laser and the waveguide. It will be appreciated that the exact position of the waveguide facet
  • (90) will be formed by the second etch as the polysilicon on the waveguide is removed before the second etch.
  • the mechanical stops are defined in the same mask as defines the facet they will be perfectly aligned.
  • the process described produces mechanical features that provide for perfect alignment with the waveguide facet in all three axes. These features may be used to align and attach a laser or a number of other different components to the wafer such as fibre optic guides, filters, isolators and photodiodes. These are only examples and this list is not exclusive.
  • the method described produces very accurate alignment to all three axes of the waveguide facet as the facet and alignment features are self aligned. This is achieved in two stages using two masks. The first producing alignment in two axes and the second providing alignment in the third.
  • a feature 70 is created in the laser 65 at a position that is very well defined with respect to the laser stripe 72.
  • This feature is preferably created using the same mask that is used to create the laser stripe, ensuring that the feature is aligned to the facet with a very high precision.
  • the laser alignment feature may be created using a combination of dry and wet etch processes and must be sufficiently far away from the laser stripe 72 so as not to interfere with laser operation.
  • the height of the laser alignment feature 70 can either be defined with a selective etch stop layer in the laser, or sufficient accuracy may be achieved by dry etching without a stop layer. It will be appreciated that the alignment is both a surface 74 and edge alignment 76.
  • the laser includes a mode expander to better match the laser mode shape to the waveguide. If an expanded mode laser is not used, there will be significant losses unless the waveguide is lensed.
  • the laser is attached to the waveguide using solder bumps 76 under the laser stripe in area 74 of Figure 3 between the pair of alignment features 30. The solder bumps 76 pull the laser down onto the top of the reference surface and conduct heat away from the laser into the silicon substrate. The very high thermal conductivity of silicon makes it a preferred substrate material when the process described is used to mount a laser.
  • the laser is mounted, flipped so that the active layer is down onto the waveguide and soldered into position. During soldering the laser is pushed against the mechanical stops 60 and the shaped projections 40. Alternatively, the solder bumps could be offset slightly causing them to pull the laser up to the stops. It will be appreciated that the embodiment described has the advantage of providing a very high precision alignment of the alignment features to the waveguide facet. Alignment along two axes is provided by creating the alignment features in the same masks as the waveguides and the facet. Alignment along the third axes is achieved by forming mechanical stop during the same process which creates the facet.
  • the laser output can be aligned with such precision to the waveguide structure that the laser may be positioned and attached entirely passively, that is without any feedback.
  • the process enables many lasers to be fabricated onto a single silicon wafer thus providing a low cost, high volume, assembly technique.
  • the waveguide has been described as a silica waveguide, but other waveguides may be used, for example silicon or polymer waveguides.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Optical Integrated Circuits (AREA)

Abstract

L'invention concerne la formation d'un guide d'onde au moyen d'un seul masque, de manière à définir les caractéristiques du guide d'onde et d'alignement sur la couche centrale. L'arrêt de la gravure s'effectue sur les caractéristiques d'alignement, lorsque la couche de revêtement est ajoutée et un second masque constituant un arrêt mécanique est défini et une facette du guide d'onde est alignée à l'arrêt. La zone du masque est gravée vers le bas sur le substrat, indépendamment des caractéristiques d'alignement protégées. Le laser et d'autres composants peuvent être attachés. Les lasers peuvent être fixés par des perles de soudure et présenter leur propre caractéristique d'alignement, indépendamment de la facette du laser.
PCT/GB2002/004692 2001-10-17 2002-10-17 Hybridation laser Ceased WO2003034115A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002334184A AU2002334184A1 (en) 2001-10-17 2002-10-17 Coupling a semiconducter laser to an optical waveguide

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0124916A GB2381082A (en) 2001-10-17 2001-10-17 Optical waveguide with alignment feature in core layer
GB0124916.8 2001-10-17

Publications (2)

Publication Number Publication Date
WO2003034115A2 true WO2003034115A2 (fr) 2003-04-24
WO2003034115A3 WO2003034115A3 (fr) 2003-10-16

Family

ID=9924017

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2002/004692 Ceased WO2003034115A2 (fr) 2001-10-17 2002-10-17 Hybridation laser

Country Status (3)

Country Link
AU (1) AU2002334184A1 (fr)
GB (1) GB2381082A (fr)
WO (1) WO2003034115A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019509635A (ja) * 2016-02-19 2019-04-04 メイコム テクノロジー ソリューションズ ホールディングス インコーポレイテッド フォトニック集積回路におけるレーザアライメントのための技術

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Publication number Priority date Publication date Assignee Title
GB1547794A (en) * 1975-10-30 1979-06-27 Rca Corp Optical waveguide coupler employing deformed shape fibre-optic core coupling portion
CA1255382A (fr) * 1984-08-10 1989-06-06 Masao Kawachi Circuit integre optique hybride a guides d'alignement
JP3133474B2 (ja) * 1992-03-18 2001-02-05 古河電気工業株式会社 ガイド溝付き光導波路の製作方法
FR2694841B1 (fr) * 1992-08-14 1994-09-09 Commissariat Energie Atomique Procédé d'hybridation et de positionnement d'un composant opto-électronique et application de ce procédé au positionnement de ce composant par rapport à un guide optique intégré.
JPH0772347A (ja) * 1993-06-17 1995-03-17 Furukawa Electric Co Ltd:The ガイド溝付き光導波路の製作方法
JP3117107B2 (ja) * 1993-08-03 2000-12-11 シャープ株式会社 光集積回路素子の組立構造
WO1996002861A1 (fr) * 1994-07-18 1996-02-01 Sheem Sang K Moyens d'interconnexion a verrouillage face contre face, pour fibres optiques et pour autres composants optiques, et procedes de fabrication correspondants
US5721797A (en) * 1996-05-28 1998-02-24 Lucent Technologies Inc. Apparatus and method for mounting a laser to a substrate and aligning the laser with an optical conduit
FR2760101B1 (fr) * 1997-02-24 1999-04-16 Alsthom Cge Alcatel Procede d'assemblage d'un dispositif opto-hybride
HK1049705A1 (zh) * 1999-07-16 2003-05-23 Hybrid Micro Technologies Aps 硅板上有源与无源光学部件的混合集成

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019509635A (ja) * 2016-02-19 2019-04-04 メイコム テクノロジー ソリューションズ ホールディングス インコーポレイテッド フォトニック集積回路におけるレーザアライメントのための技術
JP7155007B2 (ja) 2016-02-19 2022-10-18 メイコム テクノロジー ソリューションズ ホールディングス インコーポレイテッド フォトニック集積回路におけるレーザアライメントのための技術
JP2022189842A (ja) * 2016-02-19 2022-12-22 メイコム テクノロジー ソリューションズ ホールディングス インコーポレイテッド フォトニック集積回路におけるレーザアライメントのための技術
US11658459B2 (en) 2016-02-19 2023-05-23 Macom Technology Solutions Holdings, Inc. Techniques for laser alignment in photonic integrated circuits
JP7615098B2 (ja) 2016-02-19 2025-01-16 メイコム テクノロジー ソリューションズ ホールディングス インコーポレイテッド フォトニック集積回路におけるレーザアライメントのための技術

Also Published As

Publication number Publication date
GB0124916D0 (en) 2001-12-05
AU2002334184A1 (en) 2003-04-28
WO2003034115A3 (fr) 2003-10-16
GB2381082A (en) 2003-04-23
GB2381082A8 (en) 2003-06-05

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