Resonant optical power control device assemblies

• US 20020037132A1
• Filed: 02/16/2001
• Published: 03/28/2002
• Est. Priority Date: 02/17/2000
• Status: Active Grant

• Current Assignee: Hoya Corporation USA (Hoya Corporation)
• Original Assignee: Xponent Photonics, Inc. (Hoya Corporation)
• Inventors: Vernooy, David W., Vahala, Kerry J., Sercel, Peter C., Painter, Oskar J., Hunziker, Guido, Lee, Robert B.
• Granted Patent: US 6,891,996 B2
• Time in Patent Office: Days
• US Class Current: 385/30
• CPC Class Codes: B23K 2101/35 Surface treated articles
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/30 Organic material
• CPC Class Codes: B23K 2103/42 Plastics B23K2103/16 takes precedence
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 2103/52 Ceramics
• CPC Class Codes: B23K 26/0823 Devices involving rotation of the workpiece
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: G02B 6/02052 comprising optical elements other than gratings, e.g. filters comprising gratings G02B6/02057
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: G02B 6/2852 using tapping light guides arranged sidewardly, e.g. in a non-parallel relationship with respect to the bus light guides (light extraction or launching through cladding, with or without surface discontinuities, bent structures)
• CPC Class Codes: G02B 6/29323 Coupling to or out of the diffractive element through the lateral surface of the light guide evanescent grating couplers G02B6/29332
• CPC Class Codes: G02B 6/29338 Loop resonators
• CPC Class Codes: G02B 6/2934 Fibre ring resonators, e.g. fibre coils
• CPC Class Codes: G02B 6/29343 Cascade of loop resonators
• CPC Class Codes: G02F 1/0118 by controlling the evanescent coupling of light from a fibre into an active, e.g. electro-optic, overlay
• CPC Class Codes: G02F 1/225 in an optical waveguide structure
• CPC Class Codes: G02F 2203/15 involving resonance effects, e.g. resonantly enhanced interaction

Abstract

The present invention applies to resonant optical power control device assemblies and methods relating thereto, and includes an alignment device preferably including one or more waveguide-alignment grooves, resonator alignment grooves, and alignment groves for a second optical element including a modulator. One embodiment includes a transmission optical waveguide, a circumferential-mode optical resonator; and a second optical element, optionally including one or more of an optical modulator or a second transmission optical waveguide, and optionally including a modulator optical control element. In this embodiment, the alignment grooves reliably establish and stably maintain evanescent optical coupling between the optical elements positioned in such grooves. A method for assembling a resonant optical power control devices is also disclosed. The method includes: fabricating an alignment substrate having various alignment grooves; positioning and securing the various optical elements in their corresponding alignment grooves so that the resonator and the transmission optical waveguide are optically coupled (through close proximity and/or direct contact between them), and similarly optically coupling the resonator and any second optical element. Alignment grooves in the substrate and/or in one or more of the optical elements are fabricated at proper depths and positions and preferably with mating grooves and/or flanges to enable the optical coupling without extensive active alignment procedures. A modulator can alternatively be provided as an integral component of the resonator, directly on the resonator, or as a separate assembly positioned on and secured with respect to the alignment substrate. The modulator enables control of the resonator, which in turn controls the optical power transmitted through the transsmision optical waveguide and/or the second optical element. Structures may also be provided for suppressing undesired optical modes and/or resonances associated with resonators and/or alignment structures on the optical fiber.

Claims

1. A resonant optical modulator assembly, comprising:

a. an alignment housing, the housing including a waveguide-alignment groove and a resonator alignment groove;

b. a transmission optical waveguide, the waveguide being positioned within the waveguide alignment groove and secured to the alignment housing, the transmission optical waveguide being arranged for transmitting therethrough an optical signal carried by a waveguide optical mode, the transmission optical waveguide also having an evanescent optical coupling segment;

c. a resonator, the resonator positioned within the resonator alignment groove and secured to the alignment device, the resonator being arranged for supporting a resonator optical mode, the resonator being positioned so that the resonator evanescently optically couples with the transmission optical waveguide coupling segment;

d. an optical modulator, the optical modulator positioned on and secured to the alignment housing, the optical modulator being evanescently optically coupled with the resonator;

e. a modulator controller, the modulator controller being operatively coupled to the optical modulator for modulating, in response to an applied control signal, at least one of;

i) a level of optical power transfer through the evanescent optical coupling between the resonator and the optical modulator;

ii) a level of optical loss of the optical modulator; and

iii) a resonant frequency of the optical modulator

thereby enabling controlled modulation of a coupling condition between the transmission optical waveguide and the resonator; and

,

f. the waveguide-alignment groove and the resonator-alignment groove being arranged so as to reproducibly establish and stably maintain evanescent optical coupling between the transmission optical waveguide and the resonator and wherein the alignment housing reproducibly establishes and stably maintains evanescent optical coupling between the resonator and the optical modulator.

2. The resonant optical modulator assembly of claim 1 wherein the resonator includes a plurality of fiber-ring resonator segments, at least two of which resonator segments are evanescently optically coupled together.

3. The resonant optical modulator assembly of claim 1 wherein the waveguide alignment groove has an enlarged central portion, thereby enabling heating and pulling of an optical fiber positioned within the waveguide-alignment groove to form a fiber optic taper segment while substantially reducing contact between the alignment housing and the fiber-optic-taper segment.

4. The resonant optical modulator assembly of claim 1 wherein the transmission optical waveguide comprises a transmission fiber optic waveguide, the evanescent optical coupling segment of the transmission fiber optic waveguide comprises a fiber-optic-taper segment, and the fiber-optic-taper segment is partially wrapped around a portion of an outer circumference of at least one of the fiber-ring resonators.

5. The resonant optical modulator assembly of claim 4 further including a wrapping adjuster, the wrapping adjuster being arranged so as to modify the spatial extent of the wrapped portion of the outer circumference of the fiber-ring resonator by the transmission fiber optic waveguide evanescent optical coupling segment, thereby enabling adjustment of the level of evanescent optical coupling between the transmission fiber optic waveguide and the fiber-ring resonator.

6. The resonant optical modulator assembly of claim 5, wherein the alignment housing is further arranged for engaging the fiber-optic-taper segment and holding the fiber-optic-taper segment in a partially wrapped engagement around the fiber-ring resonator, the taper segment support members being positioned on the alignment housing with the resonator alignment groove therebetween.

7. A method for assembling a resonant optical modulator comprising the steps of:

a. positioning a fiber optic waveguide within a waveguide alignment groove in an alignment housing and securing the waveguide to the alignment groove;

b. positioning a resonator within a resonator alignment groove in on alignment housing and securing the resonator to the alignment groove;

c. positioning and securing an optical modulator on the alignment housing, the optical modulator being operatively coupled to the resonator; and

d. operatively coupling a modulator controller to the optical modulator.

8. A resonant optical filter assembly for an optical WDM system, comprising:

a. an alignment housing including a first waveguide-alignment groove, a second waveguide-alignment groove, and a resonator-alignment groove;

b. a first transmission optical waveguide, the first waveguide being positioned within the first waveguide-alignment groove and secured to the alignment housing, and arranged for transmitting therethrough a plurality of optical signals, each carried by a respective waveguide optical mode corresponding to an optical channel of the WDM system, the first transmission optical waveguide having an evanescent optical coupling segment with an evanescent portion of each waveguide optical mode extending transversely beyond a surface of the evanescent optical coupling segment;

c. a second transmission optical waveguide, the second waveguide being positioned within the second waveguide-alignment groove and secured to the alignment housing, and arranged for transmitting therethrough a plurality of optical signals, each carried by a respective waveguide optical mode corresponding to an optical channel of the WDM system, the second transmission optical waveguide having an evanescent optical coupling segment with an evanescent portion of the waveguide optical mode extending transversely beyond a surface of the evanescent optical coupling segment; and

,

d. a resonator, the resonator being positioned within the resonator-alignment groove and secured to the alignment housing, and arranged for supporting a resonant optical mode, the resonator being positioned so as to be evanescently optically coupled to the first transmission optical waveguide coupling segment and the second transmission optical waveguide coupling segment.

9. The resonant optical filter assembly of claim 8, wherein the resonant optical filter assembly is an optical WDM slicer/interleaver.

10. The resonant optical filter assembly of claim 8, wherein the resonant optical filter is an optical channel add/drop filter.

11. The resonant optical filter assembly of claim 8, wherein the first and second waveguides are fiber optic waveguides and the evanescent optical coupling segments includes fiber-optic-taper segments, and wherein at least one of the first and second waveguide-alignment grooves has an enlarged central portion, thereby enabling heating and pulling of an optical fiber positioned within the centrally-enlarged waveguide-alignment groove to form the fiber-optic-taper segment of the respective waveguide while substantially reducing contact between the alignment housing and the respective fiber-optic-taper segment.

12. A method for assembling a resonant optical filter assembly comprising the steps of:

a. positioning a first waveguide within a first waveguide-alignment groove on an alignment housing and securing the first waveguide to the alignment housing;

b. positioning a second waveguide within a second waveguide-alignment groove on an alignment housing and securing the second waveguide to the alignment housing; and

,

c. positioning the resonator within a resonator-alignment groove on an alignment housing and securing the resonator to the alignment housing.