EP-4735937-A1 - INTEGRATED OPTICAL CIRCUIT SWITCH DEVICES AND METHODS OF FABRICATING SAME

Abstract

The present disclosure is directed to optical switch networks having optical switches that controllably reroute light between bus optical waveguides. An optical switch comprises a shunt optical waveguide disposed in a gap vertically between the first bus optical waveguide formed in a first waveguide layer and a second bus optical waveguide formed in a second waveguide layer and configured to moveably optically couple the first and second bus optical waveguides upon activation. The first waveguide layer and the optical switch are formed on a first substrate and the second waveguide layer is formed on a second substrate bonded to the first substrate, or mechanically supported by a plurality of anchors extending between the first and second substrates. The optical switch network includes sensors for identifying a failed optical switch and recovery optical waveguides and optical switches that provide recovery optical paths to bypass the failed optical switch.

Inventors

• SEOK, TAE JOON
• ZHANG, Xiaosheng
• WU, Ming Chiang A.
• KANEDA, NORIAKI
• KWON, KYUNGMOK

Assignees

• Neye Systems, Inc.

Dates

Publication Date

20260506

Application Date

20240628

Claims (20)

1. 1. An integrated optical circuit comprising: a first waveguide layer formed on a substrate, the first waveguide layer having formed therein a first bus optical waveguide; a second waveguide layer having formed therein a second bus optical waveguide; an optical switch comprising a shunt optical waveguide disposed in a gap vertically between the first and second bus optical waveguides and configured to moveably optically couple the first bus optical waveguide and the second bus optical waveguide upon activation to redirect light between the first and second bus optical waveguides; and a plurality of vertical vias serving as mechanical anchors and electrical connections between the first and second waveguide layers to fixedly suspend the second waveguide layer above the first waveguide layer, the plurality of vertical vias formed of a material that is etch- selective to a sacrificial material removed from the gap during fabrication.
2. 2. The integrated optical circuit of Claim 1, wherein the shunt optical waveguide is configured to be optically isolated from the first and second bus optical waveguides when the optical switch is in an OFF state, and to optically couple the first and second bus optical waveguides when the optical switch is in an ON state.
3. 3. The integrated optical circuit of Claim 1, wherein a thickness of the second waveguide layer is less than 800 microns.
4. 4. The integrated optical circuit of Claim 1, wherein the optical switch further comprises at least one microelectromechanical systems (MEMS) actuator configured to activate the shunt optical waveguide to optically couple a first end region thereof to the first bus optical waveguide and a second end region thereof to the second bus optical waveguide.
5. 5. The integrated optical circuit of Claim 1, further comprising an inter-layer optical coupler configured to optically couple an end of the first bus optical waveguide to an optical port formed on the second waveguide layer, or to optically couple an end of the second bus optical waveguide to an optical port formed on the first waveguide layer.
6. 6. The integrated optical circuit of Claim 5, wherein the optical port comprises a fiber- to-wavcguidc optical coupler.
7. 7. The integrated optical circuit of Claim 1, further comprising a first optical alignment structure in the first waveguide layer or on the substrate, and a second optical alignment structure in the second waveguide layer, the first optical alignment structure configured to be optically coupled to the second optical alignment structure to form a loop back waveguide structure.
8. 8. The integrated optical circuit of Claim 1, wherein one or more of the plurality of vertical vias comprises a conductive via.
9. 9. The integrated optical circuit of Claim 8, wherein the one or more of the plurality of vertical via comprises a dielectric region.
10. 10. A method of fabricating an integrated optical circuit device, the method comprising: fabricating a first wafer comprising: lithographically patterning to form a first bus optical waveguide extending within a first waveguide layer on a front side of a first substrate, and forming on the first substrate an optical switch structure comprising a shunt optical waveguide at least partly fixedly buried in a sacrificial material; fabricating a second wafer comprising lithographically patterning to form a second bus optical waveguide extending within a second waveguide layer on a front side of a second substrate; bonding the front side of the second wafer to the front side the first wafer; removing the second substrate; forming a plurality of vertical vias through the second waveguide layer and further through the sacrificial material, the plurality of vertical vias serving as mechanical anchors and electrical connections between the first and second waveguide layers; and selectively removing the sacrificial material to release the shunt optical waveguide to configure the shunt optical waveguide to moveably optically couple the first bus optical waveguide and the second bus optical waveguide, upon activation, to redirect light between the first and second bus optical waveguides.
11. 11. The method of Claim 10, wherein forming the optical switch structure comprises forming a microclcctromcchanical systems (MEMS) structure.
12. 12. The method of Claim 11, wherein selectively removing the sacrificial material comprises removing the sacrificial material from the MEMS structure to release a MEMS actuator configured to activate the shunt optical waveguide.
13. 13. The method of Claim 12, wherein the sacrificial material comprises a material that is etch-selective against materials of the MEMS actuator and the shunt optical waveguide.
14. 14. The method of Claim 10, wherein bonding the second wafer to the first wafer comprises optically aligning the shunt optical waveguide to the second bus optical waveguide such that after removing the sacrificial material the shunt optical waveguide moveably optically couples the first bus optical waveguide and the second bus optical waveguide upon activation.
15. 15. The method of Claim 10, wherein bonding the second wafer to the first wafer comprises optically coupling a pair of optically isolated waveguides formed on the first wafer and a loop back waveguide section formed on the second wafer.
16. 16. The method of Claim 10, wherein forming the plurality of vertical vias comprises forming a conductive line vertically extending from the first wafer to the second wafer.
17. 17. An integrated optical circuit device comprising: a first waveguide layer formed on a first substrate, first waveguide layer having formed therein a first bus optical waveguide; a second waveguide layer formed on a second substrate, the second waveguide layer having formed therein a second bus optical waveguide; an optical switch comprising a shunt optical waveguide disposed in a vertical gap between the first and second bus optical waveguide layers and configured to moveably optically couple the first bus optical waveguide and the second bus optical waveguide upon activation to redirect light between the first and second bus optical waveguides; and a plurality of mechanical stoppers vertically extending between the first and second substrates, wherein each mechanical stopper has a first mechanical stopper portion formed on the first substrate and a second mechanical stopper portion formed on the second substrate, wherein the second substrate is bonded to the first substrate using the plurality of mechanical stoppers such that the first bus optical waveguide is vertically separated from the second bus optical waveguide by a distance defined by the mechanical stopper.
18. 18. The integrated optical circuit device of Claim 17, wherein the plurality of mechanical stoppers are configured to establish a predefined vertical spacing between the first and second bus optical waveguides.
19. 19. The integrated optical circuit device of Claim 17, wherein the first mechanical stopper portion is bonded to the second mechanical stopper portion.
20. 20. The integrated optical circuit device of Claim 17, further comprising a first optical alignment structure in the first waveguide layer or on the first substrate and a second optical alignment structure in the second waveguide layer or on the second substrate, the first optical alignment structure configured to be optically coupled to the second optical alignment structure forming a loop back waveguide structure.

Description

INTEGRATED OPTICAL CIRCUIT SWITCH DEVICES AND METHODS OF FABRICATING SAME INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS [0001] This application claims benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63/511427, entitled “MICRO-ELECTROMECHANICAL SYSTEM OPTICAL CIRCUIT SWITCH FABRICATED ON TWO WAFERS,” filed on June 30, 2023, and U.S. Provisional Patent Application No. 63/562179, entitled “INTEGRATED OPTICAL CIRCUIT SWITCH DEVICES AND METHODS OF FABRICATING SAME,” filed on March 6, 2024, both of which are incorporated herein by reference in their entirety. BACKGROUND Field [0002] The present disclosure generally relates to optical switches used for routing optical signals in photonic systems and circuits, and more particularly to integrated optical circuit switches comprising electromechanically actuated optical switches. Description of the Related Art [0003] Performing data processing and data transport tasks in an optical domain can significantly increase data transmission and processing rates compared to electronic systems. One of the important tasks in most computing or communication systems is controlling signal paths within a network of signal channels. A switching circuit can include reconfigurable interconnections that controllably transfer signals between different channels. Optical switching circuits that provide reconfigurable optical interconnections between a plurality of optical waveguides are important building blocks in most optical processing and communication systems and their performance advantages can have a significant impact on these systems. SUMMARY [0004] In some aspects, the techniques described herein relate to an integrated optical circuit (IOC) including: a first waveguide layer having formed therein a first bus optical waveguide; a second waveguide layer having formed therein a second bus optical waveguide; an optical switch including a shunt waveguide disposed in a gap vertically between the first and second bus optical waveguide layers and configured to moveably couple the first bus optical waveguide and the second bus optical waveguide upon activation; and a pair of optical alignment structures formed in the first and second waveguide layers, wherein the optical alignment structures are optically aligned within a predetermined tolerance to correspondingly align the first and second waveguide layers and the optical switch within a predetermined tolerance such that when activated, the shunt waveguide optically couples first and second bus optical waveguides to redirect light therebetween. [0005] In some aspects, the techniques described herein relate to a method of aligning two wafers including integrated photonic devices, the method including: providing a first wafer, the first wafer including: a first waveguide layer having formed therein a first bus optical waveguide, an optical switch structure including a shunt waveguide configured to moveably optically couple the first bus optical waveguide to a second bus optical waveguide upon activation to redirect light between the first and second bus optical waveguides, and a first one of a pair of optical alignment structures including a first waveguiding structure; providing a second wafer, the second wafer including: a second waveguide layer having formed therein the second bus optical waveguide, and a second one of the pair of optical alignment structures including a second waveguiding structure; providing optical input power to the first waveguiding structure of the first one of the pair of optical alignment structures; positioning the second wafer with respect to the first wafer such that the second waveguiding structure is positioned above the first waveguiding structure; measuring an output optical power output by the second waveguiding structure as a result of optical coupling between the first and second waveguiding structures; aligning the first wafer with respect to the second wafer based on the measured output optical power; and wherein the measured output optical power directly correlates to an optical coupling strength between the first and second optical waveguides, when the optical switch structure is activated. [0006] In some aspects, the techniques described herein relate to an integrated optical circuit (IOC) including: a first waveguide layer having formed therein a first bus optical waveguide; a second waveguide layer having formed therein a second bus optical waveguide; an optical switch including a shunt waveguide disposed in a gap vertically between the first and second bus optical waveguide layers and configured to moveably couple the first bus optical waveguide and the second bus optical waveguide upon activation; and a pair of physical alignment structures formed on the first and second waveguide layers, wherein the physical alignment structures are physically coupled to align the first and second waveguide layers and the optical switch within a predetermined toler