In this paper, we report an advance in increasing core size of effective single-mode chirally-coupled-core (CCC) Ge-doped and Yb-doped double-clad fibers into 55µm to 60µm range, and experimentally demonstrate their robust single-mode performance. Theoretical and numerical description of CCC fibers structures with multiple side cores and polygon-shaped central core is consistent with experimental results. Detailed experimental characterization of 55µm-core CCC fibers based on spatially and spectrally resolved broadband measurements (S2 technique) shows that modal performance of these large core fibers well exceeds that of standard 20μm core step-index large mode area fibers.

Single-mode chirally-coupled-core fibers with larger than 50µm diameter cores

Over the past two decades, fiber laser technologies have matured to such an extent that they have captured a large portion of the commercial laser marketplace. Yet, there still is a seemingly unquenchable thirst for ever greater optical power to levels where certain deleterious light-matter interactions that limit continued power scaling become significant. In the past decade or so, the industry has focused mainly on waveguide engineering to overcome many of these hurdles. However, there is an emerging body of work emphasizing the enabling role of the material. In an effort to underpin these developments, this paper reviews the relevance of the material in high power fiber laser technologies. As the durable material-of-choice for the application, the discussion will mainly be limited to silicate host glasses. The discussion presented herein follows an outward path, starting with the trivalent rare earth ions and their spectroscopic properties. The ion then is placed into a host, whose impact on the spectroscopy is reviewed. Finally, adverse interactions between the laser lightwave and the host are discussed, and novel composition glass fiber design and fabrication methodologies are presented. With deference to the symbiosis required between material and waveguide engineering in active fiber development, this review will emphasize the former. Specifically, where appropriate, materials-based paths to the enhancement of laser performance will be underscored.

/pdf/materials-for-optical-fiber-lasers-a-review-2n45z3gaeq.pdf

Materials for optical fiber lasers: A review

An optoelectronics chip-to-chip interconnects system is provided, including at least one packaged chip to be connected on the printed-circuit-board with at least one other packaged chip, optical-electrical (O-E) conversion mean, waveguide-board, and (PCB). Single to multiple chips interconnects can be interconnected provided using the technique disclosed in this invention. The packaged chip includes semiconductor die and its package based on the ball-grid array or chip-scale-package. The O-E board includes the optoelectronics components and multiple electrical contacts on both sides of the O-E substrate. The waveguide board includes the electrical conductor transferring the signal from O-E board to PCB and the flex optical waveguide easily stackable onto the PCB to guide optical signal from one chip-to-other chip. Alternatively, the electrode can be directly connected to the PCB instead of including in the waveguide board. The chip-to-chip interconnections system is pin-free and compatible with the PCB. The main advantages of this invention are to use the packaged chip for interconnection and the conventional PCB technology can be used for low speed electrical signal connection. Also, the part of the heat from the packaged chip can be transmitted to the PCB through the conductors, so that complex cooling system can be avoided.

Stackable optoelectronics chip-to-chip interconnects and method of manufacturing

A microneedle applicator is provided which has two roughly concentric portions which may be, for example, a solid disk and an annulus surrounding it. On the skin-facing side of the inner portion of the applicator a microneedle array is located. The outer portion of the applicator is placed against the skin, contacting it at a zone. The microneedle array is then pressed towards the skin.

Applicators for microneedles

We propose a novel all-solid rod-type fiber structure that presents a cylindrical symmetry and low refractive-index contrasts. Effectively single-mode propagation for the fundamental mode is ensured thanks to resonant couplings between Higher Order Modes (HOMs) and cladding modes. Numerical simulations demonstrate the possibility of achieving a fundamental mode effective area as large as 5000µm2 at a wavelength of 1.06µm in fibers ensuring a high leakage loss ratio (>100) between the HOMs and the fundamental mode while keeping the fundamental mode leakage losses at a level lower than 0.2dB/m. Further scaling to an effective area of 12,200µm2 at 1.06µm in an effectively singlemode fiber is also presented by exploiting the power delocalization of several HOMs on top of the high-leakage loss filtering.

Mode area scaling with multi-trench rod-type fibers.

An effectively single-mode all-solid photonic bandgap fiber with large effective area and low bending loss for compact high-power all-fiber lasers is fully investigated. The pitch dependencies of effective area, bending loss, and effectively single-mode operation are discussed numerically and experimentally. The calculation results indicate that an effectively single-mode all-solid photonic bandgap fiber with an effective area of more than 500 μm2 and a bending loss of less than 0.1 dB/m at a bending radius of 10 cm can be realized by choosing optimum fiber parameters. In a fabricated effectively single-mode all-solid photonic bandgap fiber with 48.0 μm core, the effective area of 712 μm2, the effectively single-mode operation, and the bending loss of less than 0.1 dB/m at a bending radius of 10 cm are achieved simultaneously at 1064 nm.

Effectively single-mode all-solid photonic bandgap fiber with large effective area and low bending loss for compact high-power all-fiber lasers

Fiber fuse phenomenon in hole-assisted fibers (HAFs) was investigated. Fiber fuse propagation can be stopped as designing suitable position of air holes in HAF.

/pdf/fiber-fuse-phenomenon-in-hole-assisted-fibers-13jwhdcmp3.pdf

Fiber fuse phenomenon in hole-assisted fibers

Photodarkening phenomenon in ytterbium (Yb)-doped silica glasses was experimentally investigated by measurements
such as electron spin resonance (ESR), X-ray absorption fine-structure (XAFS), and optical transmittance. A
predominant increase of Al-oxygen hole center (OHC) was observed for Al-Yb co-doped silica glasses both by the
incidence of pump light and by gamma-ray irradiation. It was also recognized that the optical transmission loss similarly
increased in both cases. These results indicate that the formation of Al-OHC is the prime cause of the excess loss
induced by photodarkening. XAFS measurement indicated that the second-nearest-neighbor atoms around Yb may be
related to the mechanism of photodarkening phenomenon.

Gamma-radiation-induced photodarkening in ytterbium-doped silica glasses

A dispersion compensating optical fiber for NZ-DSFs, includes: an uncovered dispersion compensating optical fiber; a double-layered resin coating disposed around the uncovered dispersion compensating optical fiber; and an outer coating layer having a thickness of 3 to 7 μm, containing silicone in an amount of 1 to 5% by weight, and disposed around the double-layered resin coating. The outer diameter of the uncovered dispersion compensating optical fiber is in a range from 90 to 125 μm, an outer diameter of the dispersion compensating optical fiber is in a range from 180 to 250 μm, and the amount of silicone contained in the outer coating layer is determined such that an adhesive property of the outer coating layer is 1 gf/mm or less.

Dispersion compensating optical fiber, and dispersion compensating optical fiber module

PROBLEM TO BE SOLVED: To provide an instrument for carrying medicinal material which is inserted through the skin without pain and fixed to the skin surface of a human body with good stability, and a manufacturing method of the same. SOLUTION: This instrument for carrying a medicinal material includes: a number of fine substantially conical projecting parts 12 provided in an alignment state; and a plate-like base 11 bearing the projecting parts, wherein the projecting parts and the plate-like base are formed of different kinds of raw materials. This manufacturing method for the instrument for carrying a medicinal material includes: a process (A) of forming a plate-like base formed of polymer raw material on one side of obverse and reverse principal surfaces of a base plate formed of inorganic raw material; a process (B) of forming a resist pattern in each of the projecting part forming positions on the other side of the base plate corresponding to the projecting parts provided in the alignment state; and a process (C) of obtaining a medicinal material carrying instrument bearing a number of substantially conical projecting parts made of inorganic raw material on the plate-like base formed of polymer raw material. COPYRIGHT: (C)2007,JPO&INPIT

Munehisa Fujimaki

Papers

Effectively single-mode all-solid photonic bandgap fiber with large effective area and low bending loss for compact high-power all-fiber lasers

Fiber fuse phenomenon in hole-assisted fibers

Gamma-radiation-induced photodarkening in ytterbium-doped silica glasses

Dispersion compensating optical fiber, and dispersion compensating optical fiber module

Instrument for carrying medicinal material and manufacturing method of the same