# US 10,481,355 B2 · Optical assembly > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,481,355 B2 - Document ID: US10481355B2 - Status: Granted - Kind: B2 - Application number: 15/958,883 - Filed: 2018-04-20 - Published: 2019-10-24 - Granted: 2019-11-19 - Earliest claimed: 2018-04-20 - Assignees: Sicoya GmbH - Applicants: Sicoya GmbH - Inventors: Thorsten Kettler; Moritz Grehn; Christoph Theiss; Stefan Meister - Web page: https://patentgrep.com/patent/US10481355B2 ## CPC - G02B 6/4206: {Optical features (G02B6/4207, G02B6/421 take precedence)} - G02B 6/124: Geodesic lenses or integrated gratings - G02B 6/4207: {with optical elements reducing the sensitivity to optical feedback (anti-reflection devices specially adapted for lasers, see H01S3/0064)} - G02B 6/4214: {the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device (G02B6/4246 takes precedence)} - G02B 6/43: Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections - H01S 5/02: Structural details or components not essential to laser action - H01S 5/02255: using beam deflecting elements - H04B 10/503: {Laser transmitters} - H04B 10/801: {using optical interconnects, e.g. light coupled isolators, circuit board interconnections} - H10W 90/00: Package configurations - G02B 6/32: having lens focusing means {positioned between opposed fibre ends (with lens being an integral part of the single fibre end G02B6/262)} - H01S 5/005: {Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping (H01S5/026, H01S5/18388 take precedence)} - H01S 5/0071: {for beam steering, e.g. using a mirror outside the cavity to change the beam direction} - H01S 5/02216: Butterfly-type, i.e. with electrode pins extending horizontally from the housings - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL - H04B: TRANSMISSION - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract An embodiment of the invention relates to an optical assembly comprising an optical emitter configured to generate a beam of optical radiation, a cap unit holding the optical emitter, a photonic chip comprising a coupler, and an intermediate chip arranged between the cap unit and the photonic chip, wherein the cap unit comprises a recess having a bottom section and a sidewall, wherein the optical emitter is mounted on the bottom section of the recess, wherein a section of the sidewall forms a mirror section angled with respect to the bottom section and configured to reflect said beam of optical radiation towards the coupler, and wherein the intermediate chip comprises a lens formed at a lens section of the intermediate chip's surface that faces the cap unit, said lens being configured to focus the reflected optical beam towards the coupler. ## Claims ### Claim 1 Optical assembly comprising an optical emitter configured to generate a beam of optical radiation, a cap unit holding the optical emitter, a photonic chip comprising a coupler, and an intermediate chip arranged between the cap unit and the photonic chip, wherein the cap unit comprises a recess having a bottom section and a sidewall, wherein the optical emitter is mounted on the bottom section of the recess, wherein a section of the sidewall forms a mirror section angled with respect to the bottom section and configured to reflect said beam of optical radiation towards the coupler, and wherein the intermediate chip comprises a lens formed at a lens section of the intermediate chip's surface that faces the cap unit, said lens being configured to focus the reflected optical beam towards the coupler. ### Claim 2 (depends on 1) Optical assembly of claim 1 wherein the lens comprises a first axis and a second axis that is perpendicular to the first axis, and wherein the radius of the curvature of the lens along the first axis differs from the radius of the curvature along the second axis. ### Claim 3 (depends on 2) Optical assembly of claim 2 wherein the emission direction of the optical emitter corresponds to the direction of the first axis, and the radius of the curvature along the first axis is between 2% and 15% larger than the radius along the second axis. ### Claim 4 (depends on 1) Optical assembly of claim 1 further comprising an interposer chip that is arranged between the intermediate chip and the photonic chip, wherein the interposer chip has a front surface that faces the intermediate chip and a backside surface that faces the photonic chip, and wherein the backside surface comprises a hole that is located in the beam path between the lens and the coupler. ### Claim 5 (depends on 4) Optical assembly of claim 4 wherein the hole is a through-hole that extends from the front surface to the backside surface of the interposer chip. ### Claim 6 (depends on 4) Optical assembly of claim 4 wherein a rotator is arranged within said hole. ### Claim 7 (depends on 4) Optical assembly of claim 4 wherein a rotator and a λ/2-waveplate—with respect to the wavelength of the optical radiation—are arranged within said hole. ### Claim 8 (depends on 4) Optical assembly of claim 4 wherein a polarizer, a rotator and a λ/2-waveplate—with respect to the wavelength of the optical radiation—are arranged within said hole. ### Claim 9 (depends on 4) Optical assembly of claim 4 wherein the interposer chip and the intermediate chip are bonded together by a buried oxide layer and wherein the hole extends from the backside surface of the interposer chip through the interposer chip and through the buried oxide layer to the intermediate chip. ### Claim 10 (depends on 9) Optical assembly of claim 9 wherein the interposer chip, the intermediate chip and the buried oxide layer are formed by an SOI-chip. ### Claim 11 (depends on 1) Optical assembly of claim 1 wherein the cap unit comprises an SOI-chip having a silicon top layer, a buried oxide layer, and a bottom layer, wherein the recess extends from the outer surface of the silicon top layer to the buried oxide layer or through the buried oxide layer to the bottom layer, and wherein the bottom of the recess is formed by a section of the buried oxide layer or a section of the bottom layer. ### Claim 12 (depends on 1) Optical assembly of claim 1 wherein the cap unit comprises a semiconductor substrate having a front side in which the recess is formed, and wherein said surface of the intermediate chip, in which said lens is formed, comprises at least one bonding section on which the front side of the cap unit is bonded. ### Claim 13 (depends on 12) Optical assembly of claim 12 wherein the semiconductor substrate is a (110)-oriented substrate with the front side being formed by a (110) surface and wherein the mirror section is a (111) surface. ### Claim 14 (depends on 1) Optical assembly of claim 1 wherein a first electrical contact of the optical emitter is connected to a conductive layer of the cap unit, the conductive layer of the cap unit extending from the bottom section of the recess to a first bonding section of the cap unit, the first bonding section of the cap unit being located outside the recess and bonded to a first bonding section of the intermediate chip, and wherein a second electrical contact of the optical emitter is directly bonded on a second bonding section of the intermediate chip. ### Claim 15 (depends on 14) Optical assembly of claim 14 wherein the conductive layer of the cap unit is thicker in the contact area where the optical emitter is located than outside this contact area. ### Claim 16 (depends on 14) Optical assembly of claim 14 wherein the conductive layer of the cap unit consists of two or more sublayers in the contact area and/or a conductive pad is located between the optical emitter and the conductive layer. ### Claim 17 (depends on 14) Optical assembly of claim 14 wherein the conductive layer forms a reflection coating on the mirror section. ### Claim 18 (depends on 14) Optical assembly of claim 14 wherein the conductive layer forms an electrical connection section between the bottom section of the recess and the first bonding section of the cap unit. ### Claim 19 (depends on 1) Optical assembly of claim 1 wherein the intermediate chip comprises a first conductive layer, a second conductive layer and an isolation layer and wherein the isolation layer is arranged between the first and second conductive layer and insulates the first and second conductive layer from one another. ### Claim 20 (depends on 19) Optical assembly of claim 19 wherein the isolation layer of the intermediate chip forms an antireflection layer for the lens. ### Claim 21 (depends on 1) Optical assembly of claim 1 wherein a heat spreader is mounted on a backside of the cap unit, the backside being opposed to the front side where the recess is formed. ### Claim 22 Method of fabricating an optical assembly comprising the steps of fabricating a cap unit and mounting an optical emitter thereon, the optical emitter being configured to generate a beam of optical radiation, wherein said step of forming the cap unit comprises etching a recess having a bottom section and a sidewall, and mounting the optical emitter on the bottom section of the recess, forming a photonic chip comprising a coupler, forming an intermediate chip comprising a lens and arranging the intermediate chip between the cap unit and the photonic chip, wherein a section of the sidewall forms a mirror section that is angled with respect to the bottom section and configured to reflect said beam of optical radiation towards the coupler, and wherein the lens is formed at a lens section of the intermediate chip's surface that faces the cap unit, said lens being configured to focus the reflected optical beam towards the coupler. ### Claim 23 (depends on 22) Method of claim 22 wherein said step of fabricating the cap unit further comprises depositing a conductive layer, wherein the conductive layer extends from the bottom section of the recess to a first bonding section of the cap unit located outside of the recess and forms an electric connection section, and wherein the conductive layer further forms a reflection coating on the mirror section. ### Claim 24 (depends on 22) Method of claim 22 wherein the thickness of the conductive layer is made thicker in the contact area where the optical emitter is located than outside this contact area. ### Claim 25 (depends on 22) Method of claim 22 wherein said step of fabricating the cap unit further comprises depositing solder on the bottom section of the recess before mounting the optical emitter on the bottom section of the recess. ### Claim 26 (depends on 22) Method of claim 22 wherein said step of fabricating the cap unit further comprises providing a solder stop between the bottom section of the recess and the mirror section. ### Claim 27 (depends on 22) Method of claim 22 wherein said step of fabricating the cap unit further comprises providing a solder stop that completely surrounds the mirror section. ### Claim 28 (depends on 22) Method of claim 22 wherein the recess is deeper than the thickness of the optical emitter. ### Claim 29 (depends on 22) Method of claim 22 wherein the cap unit comprises an SOI-Chip having a (110)-silicon top layer, a buried oxide layer, and a bottom layer, wherein the recess is anisotropically etched from the outer surface of the silicon top layer to the buried oxide layer or through the buried oxide layer to the bottom layer, wherein the bottom of the recess is formed by a section of the buried oxide layer or a section of the bottom layer, and wherein the mirror section is provided by a (111)-surface of the etched recess. ### Claim 30 (depends on 22) Method of claim 22 wherein forming the intermediate chip comprises etching the lens at one side of the intermediate chip. ### Claim 31 (depends on 22) Method of claim 22 wherein forming the intermediate chip comprises depositing an antireflection coating on the other side of the intermediate chip. ### Claim 32 (depends on 30) Method of claim 30 wherein forming the intermediate chip comprises depositing an antireflection coating on the lens. ### Claim 33 (depends on 22) Method of claim 22 wherein said step of fabricating the intermediate chip comprises depositing a first conductive layer, an isolation layer and a second conductive layer wherein the isolation layer is arranged between the first and second conductive layer and insulates the first and second conductive layer from one another. ### Claim 34 (depends on 33) Method of claim 33 wherein the isolation layer of the intermediate chip forms an antireflection layer on the lens. ### Claim 35 (depends on 22) Method of claim 22 wherein the sidewall of the recess or at least the mirror section are etched using KOH or TMAH. ### Claim 36 (depends on 22) Method of claim 22 further comprising the step of fabricating an interposer chip and arranging the interposer chip between the intermediate chip and the photonic chip. ### Claim 37 (depends on 36) Method of claim 36 further comprising the steps of etching a hole in the backside surface of the interposer chip and positioning the hole in the beam path between the lens and the coupler. ### Claim 38 (depends on 37) Method of claim 37 wherein said step of etching the hole comprises etching a through-hole extending from the front surface to the backside surface of the interposer chip. ### Claim 39 (depends on 22) Method of claim 22 wherein said step of etching the recess includes etching alignment marks that facilitate mounting the silicon cap in a predefined position onto the intermediate chip. ### Claim 40 (depends on 37) Optical assembly of claim 37 wherein the interposer chip comprises SOI material having a silicon substrate, a buried oxide layer and a top silicon layer and wherein said step of etching the hole comprises etching a blind hole extending from the backside surface to the buried oxide layer. ### Claim 41 (depends on 22) Method of claim 22 further comprising the steps of etching a hole in an interposer chip, and bonding the interposer chip and the intermediate chip. ### Claim 42 (depends on 41) Method of claim 41 wherein the lens is formed in the intermediate chip after bonding the interposer chip and intermediate chip. ### Claim 43 (depends on 22) Method of claim 22 further comprising the steps of bonding an interposer chip and the intermediate chip via an intermediate oxide layer and forming a sandwich, etching a through-hole in the interposer chip using the intermediate oxide layer as an etch-stop-layer, and removing the etch-stop-layer in the hole and forming a pot-hole, the bottom of which is formed by the intermediate chip.