Leland Stanford Junior University

Lucent Technologies Inc.

Hyang Kyun Kim

Gordon S Kino

Michel J F Digonnet

Vinayak Dangui

Shanhui Fan

Jonghwa Shin

Christopher Richard Doerr

Michel J Digonnet

Michel Jf Digonnet

Michel JF Digonnet

An optical fiber includes a cladding with a material having a first refractive index and a pattern of regions formed therein. Each of the regions has a second refractive index lower than the first refractive index. The optical fiber further includes a core region and a core ring having an inner perimeter, an outer perimeter, and a thickness between the inner perimeter and the outer perimeter. The thickness is sized to reduce the number of ring surface modes supported by the core ring.

Optical fiber

An optical sensor includes an optical coupler. The optical sensor further includes a photonic bandgap fiber having a hollow core and an inner cladding generally surrounding the core. The photonic bandgap fiber is in optical communication with the optical coupler. Light signals counterpropagate through the photonic bandgap fiber and return to the optical coupler. The photonic bandgap fiber has a phase thermal constant S less than 8 parts-per-million per degree Celsius.

Optical sensor utilizing hollow-core photonic bandgap fiber with low phase thermal constant

An optical sensor includes a directional coupler comprising at least a first port, a second port, and a third port. The first port is in optical communication with the second port and with the third port such that a first optical signal received by the first port is split into a second optical signal that propagates to the second port and a third optical signal that propagates to the third port. The optical sensor further includes a photonic bandgap fiber having a hollow core and an inner cladding generally surrounding the core. The photonic bandgap fiber is in optical communication with the second port and with the third port. The second optical signal and the third optical signal counterpropagate through the photonic bandgap fiber and return to the third port and the second port, respectively. The photonic bandgap fiber has a phase thermal constant S less than 8 parts-per-million per degree Celsius.

An optical fiber includes a cladding with a material having a first refractive index and a pattern of regions formed therein. Each of the regions has a second refractive index lower than the first refractive index. The optical fiber further includes a core region and a core ring surrounding the core region and having an inner perimeter, an outer perimeter, and a thickness between the inner perimeter and the outer perimeter. The thickness is sized to reduce the number of ring surface modes supported by the core ring.

Optical fiber with a core ring

A photonic-bandgap fiber includes a photonic crystal lattice with a material having a first refractive index and a pattern of regions formed therein. Each of the regions has a second refractive index lower than the first refractive index. The photonic-bandgap fiber further includes a core and a core ring surrounding the core and having an inner perimeter, an outer perimeter, and a thickness between the inner perimeter and the outer perimeter. The thickness is sized to reduce the number of ring surface modes supported by the core ring.

Photonic-bandgap fiber with a core ring

A photonic-bandgap fiber includes a photonic crystal lattice with a first material having a first refractive index and a pattern of a second material formed therein. The second material has a second refractive index lower than the first refractive index. The photonic crystal lattice has a plurality of first regions that support intensity lobes of the highest frequency bulk mode and has a plurality of second regions that do not support intensity lobes of the highest frequency bulk mode. The photonic-bandgap fiber further includes a central core formed in the photonic crystal lattice. The photonic-bandgap fiber further includes a core ring having an outer perimeter. The core ring surrounds the central core, wherein the outer perimeter of the core ring passes only through the second regions of the photonic crystal lattice.

Coupling of core modes to surface modes in an air-core photonic-bandgap fiber (PBF) can cause large propagation losses. Computer simulations analyze the relationship between the geometry and the presence of surface modes in PBFs having a triangular hole pattern and identify ranges of core characteristic dimensions (e.g., radii) for which the fiber supports no surface modes (i.e., only core modes are present) over the entire wavelength range of the bandgap. In particular, for a hole spacing &#x39b; and a hole radius &#x3c1;=0.47&#x39b;, the core supports a single mode and supports no surface modes for core radii between about 0.68&#x39b; and about 1.05&#x39b;. The existence of surface modes can be predicted simply and expediently by studying either the bulk modes alone or the geometry of the fiber without requiring a full analysis of the defect modes.

Method for configuring air-core photonic-bandgap fibers free of surface modes

The curvature, tilt, and attenuation of the passband of an optical signal is dynamically controlled by an integrated compensator that is advantageously electrically operated. The compensator arrangement can be replicated, and used to independently and dynamically control the passbands of multiple optical signals having different wavelengths, for example in a multiplexing and/or demultiplexing arrangement. Each compensator includes a &ldquo;50/50&rdquo; splitter arranged to divide an optical signal into first and second copies. One copy is applied to a first variable optical attenuator (VOA) via a tunable phase shifter, while the other copy is applied to a second VOA directly. The outputs of the first and second VOA's are then combined, for example in a planar waveguide grating. In the output on the other side of the grating, the two copies interfere. When the copy phase shift is zero, the net passband is Gaussian; when the copy phase shift magnitude is &pgr;/2, the net passband is flat; and when the copy phase shift magnitude is between &pgr;/2 and &pgr;, the net passband has a dip in the middle. Thus, the tunable phase shifter controls the passband curvature, and the VOA's control the passband tilt and attenuation level.

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Sunnyvale, CA, United States of America

Hyang Kyun Kim