Fiber-optic waveguides for transverse optical coupling

• Main Authors: ROBERT B. LEE, PETER C. SERCEL, GUIDO H. HUNZIKER
• Format: Patent
• Language: English
• Published: 04.03.2002
• Edition: 7
• Subjects: CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICAL LOGIC ELEMENTS; OPTICS; PERFORMING OPERATIONS; PHYSICS; SOLDERING OR UNSOLDERING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; TRANSPORTING; WELDING; WORKING BY LASER BEAM

A fiber-optic waveguide comprises a transverse-optical-coupling fiber segment (312) and first and second longitudinally adjacent fiber segments. The cladding layers of the adjacent segments surround the cores and encompass an optical mode propagating through the waveguide. The cladding layer of the coupling segment is asymmetrically disposed about the core, thereby yielding a coupling surface (308) and enabling the propagating optical mode to extend beyond the coupling surface. The fiber-optic waveguide may be incorporated into an optical power control device by tangentially engaging the coupling surface with a circumferential-mode optical resonator, thereby enabling control of optical power transmitted through the waveguide via modulation of circumferential-mode resonator properties and/or coupling thereto. The fiber-optic waveguide may be fabricated by circumferentially asymmetric removal of cladding material form the coupling segment. The cladding material may be removed by providing a mask, such a carbon outer fiber coatting, polymer jacket, photoresist or metal, and etching the cladding layer material ("side-etching"), for example by HF, to form the asymmetric cladding profile, auch as a saddle-like shape.