Np Photonics, Inc.

Christine Spiegelberg

Shibin Jiang

Jihong Geng

Yongdan Hu

Yushi Kaneda

Tao Luo

Ping Li

Sean Staines

Chih-Jen Chi

Ronald Pollock

Ik Joon Song

A distributed fiber sensor based on spontaneous Brillouin scattering uses a single-frequency fiber laser as a source and a cw Brillouin fiber ring laser as an OLO to optically shift the frequency of the OLO to set the Brillouin/OLO beat frequency within the bandwidth of a conventional heterodyne receiver. The distributed fiber sensor is capable of real-time measurement of both temperature and strain.

Distributed fiber sensor based on spontaneous brilluoin scattering

An all-fiber Q-switched laser includes a gain fiber spliced between narrowband and broadband fiber gratings that define a polarization-dependent resonant cavity. The narrowband grating is, for example, formed in a PM fiber to create a polarization-dependent reflection band. A modulator applies stress to the fiber chain to induce birefringence and switch the cavity Q-factor to alternately store energy in the gain fiber and then release the energy in a laser pulse.

All-fiber Q-switched laser

A compact single frequency, single-mode 2 &#x3bc;m fiber laser with narrow linewidth, &#x3c;100 kHz and preferably &#x3c;100 kHz, is formed with a low phonon energy glass doped with triply ionized rare-earth thulium and/or holmium oxide and fiber gratings formed in sections of passive silica fiber and fused thereto. Formation of the gratings in passive silica fiber both facilitates splicing to other optical components and reduces noise thus improving linewidth. An increased doping concentration of 0.5 to 15 wt. % for thulium, holmium or mixtures thereof produces adequate gain, hence output power levels for fiber lengths less than 5 cm and preferably less than 3 cm to enable single-frequency operation.

Single-frequency narrow linewidth 2 &#x3bc;m fiber laser

A short laser cavity (up to 30 cm in length) comprising a free-space tunable MEMS Fabry-Perot filter, a collimating lens and a section of erbium-doped phosphate gain fiber (2-25 cm) is formed between a pair of broadband reflectors. The cavity is optically pumped to excite the erbium ions and provide gain, which establishes an initial longitudinal mode structure that spans the C-band with a mode spacing of at least 0.3 GHz and a roundtrip unsaturated gain of at least 8 dB over the tuning range. A controller tunes the MEMS filter, which has a filter function whose spectral width is at most ten and preferably less than four times the longitudinal mode spacing, to align its transmission maxima to one of a plurality of discrete output wavelengths that span the C-band. A thermal control element adjusts the longitudinal mode structure to align a single mode with the transmission maxima of the filter. Because the spectral width of the filter function is narrow, laser emission will be limited to a single longitudinal mode.

Erbium-doped phosphate-glass tunable single-mode fiber laser using a tunable fabry-perot filter

A narrow-linewidth high-power single-frequency laser is realized by pumping a laser cavity with a pair of polarized single-mode pump lasers that are driven below their respective 'micro-kink' regions and combined with a polarized beam combiner. The pump lasers emit at the same wavelength and include a length of polarization-maintaining (PM) fiber to maintain the polarization of the respective pumps. The laser cavity is selected from microchip, fiber and waveguide devices and is provided with optical feedback. This laser is capable of producing a stable high-power single-mode signal with a very narrow linewidth, e.g. less than 10 kHz and preferably less than 3 kHz.

High-power narrow-linewidth single-frequency laser

A compact low-cost continuous single-mode fiber laser delivers output powers in excess of 50 mW over the C-band (1530 nm-1565 nm). The phosphate glass fiber supports the high doping concentrations of erbium and ytterbium (Er:Yb) without self-pulsation that are required to provide sufficient gain per centimeter needed to achieve high power in the ultra short cavity lengths necessary to support single-mode lasers. The use of fiber drawing technology provides a lower cost solution than either combined solution doping/MCVD fiber fabrication or waveguide fabrication. The ability to multi-mode clad pump the fiber further reduces cost, which is critical to the successful deployment of fiber lasers in the burgeoning metro markets.

Rare-earth doped phosphate-glass single-mode fiber lasers

A long-long coupled-cavity glass laser includes a pair of active waveguide cavities that are coherently coupled using a passive waveguide cavity. The active and passive waveguide cavities are of sufficient length so that multiple supermodes and multiple peaks in the coupling coefficient are created over the width of the gain spectra. The supermodes are gain flattened so that the one supermode that coincides with a peak in the coupling coefficient will oscillate. Tunability is achieved by changing the optical path length of either the passive or active waveguide cavities to match a different supermode to a different coupling coefficient peak.

Growing community of inventors

Tucson, AZ, United States of America

Christine Spiegelberg