Recently, mode instability was observed in optical fiber lasers at high powers, severely limiting power scaling for single-mode outputs. Some progress has been made towards understanding the underlying physics. A thorough of effect is critical continued this very important technology area. Mode fibers is, fact, a manifestation stimulated thermal Rayleigh scattering. In work, quasi-closed-form solution nonlinear coupling coefficient found scattering fibers. The results help to significantly...

We propose and demonstrate a novel approach in optical fiber design which the waveguide is formed by ring of large air holes surrounding solid silica core. With an appropriate choice geometrical configuration, robust single-transverse-mode propagation with record effective area 1417 microm2, verified various methods, was demonstrated. A breakthrough made toward development practical ultra-high-power lasers as we observed negligible loss at bending diameters small 15 cm.

Leakage channel fibers, where few air holes form a core, can be precisely engineered to create large leakage loss for higher-order modes, while maintaining negligible transmission the fundamental mode. This unique property used designing optical fibers with effective area, which supports robust mode propagation. The in design also enable bend resistant. principles of and operation regime are outlined, demonstrating potential this approach that propagate core diameter exceeding 100 μm....

An empirical TMI threshold formula is derived based on a recently developed model and used to analyze the power-scaling performance of ytterbium-doped silica glass YAG (Y3Al5O12) lutetia (Lu2O3) single-crystalline fiber amplifiers. Overall, lasers are found scale potentially higher average powers due their thermal conductivities compared glass. This work serves as useful extension earlier works shines significant new light optimal amplifier designs for maximum output power with considered.

Simultaneous laser operation of three single-frequency modes from an inhomogeneously broadened Er-doped twincore fiber loop is reported. Equal output power 390 μW, separation 0.5 nm, and linewidth <10 kHz were measured for each mode in a travelling wave cavity comprising single gain medium. In addition up to eight wavelength has been observed, demonstrating that EDFA's can provide channel equalization eight-channel multiamplifier optical network.

A comprehensive survey of photosensitivity in silica glasses and optical fiber is reviewed. Recent work on understanding the mechanisms contributing to germanium or aluminum doped discussed within framework photoelastic densification models.

We report the amplification of 10-100-pJ semiconductor diode pulses to an energy 158 microJ and peak powers >100 kW in a multistage fiber amplifier chain based on single-mode, large-mode-area erbium-doped design. To our knowledge these results represent highest single-mode pulse extracted from any doped-fiber system.

The device characteristics of Er/sup 3+/,Yb/sup 3+/ single frequency fiber lasers are reported. A 5-cm long 1550-nm distributed feedback laser with 4 mW output power is shown to have excellent specifications in terms optical linewidth, signal-to-noise ratio (SNR), relative intensity noise, side-mode suppression and polarization purity. For higher applications, a 1.5 cm grating-based 60 net efficiency 12% demonstrated.

Boron- and germanium-doped highly photosensitive cladding is used in a novel design to achieve Er/Yb-doped fibers, permitting short, strong gratings (length ≈1 cm, reflectivity >99%) be written without hydrogenation. The high absorption at 980 nm Er/Yb fibers permits efficient pump over short device length, which ideal for achieving single-frequency fiber lasers. Both Bragg-grating reflector distributed-feedback lasers with slope efficiencies of 25% respect launched power have been realized...

Leakage channel fibers (LCFs) have demonstrated their ability to significantly extend the effective mode area of a fundamental while maintaining robust single-mode operation. These are designed strong built-in filtering that effectively suppresses propagation all higher order modes keeping fundamental-mode loss minimum, and, therefore, extending regime Recently, all-glass LCFs been as significant improvement over designs with air holes. can not only be manufactured much improved consistence...

Single-mode operation in a large-mode-area fiber laser is highly desired for power scaling. We have, the first time, demonstrated 50μm-core-diameter Yb-doped all-solid photonic bandgap with mode area over 4 times that of previous demonstration. 75W output has been generated diffraction-limited beam and an efficiency 70% relative to launched pump power. have also experimentally confirmed robust single-mode regime exists near high frequency edge bandgap. These fibers only guide light within...

We demonstrate that the strong 4-level Yb emission in a fiber laser can be almost completely suppressed an all-solid double-clad photonic bandgap fiber, resulting highly efficient high-power monolithic lasers operating at 3-level system. have achieved single-mode continuous wave output power of ~151W ~978nm with efficiency 63% respect to launched pump practical configuration for first time. The demonstrated this work are setting new records diffraction-limited ~978nm.

There has been very little progress in the power scaling of Er/Yb fiber lasers over a decade, reflecting difficulties involved. Here we report, to best our knowledge, new record 302 W single-mode from an master oscillator amplifier (MOPA) with optical efficiency 56%, near quantum limit. This is made possible by development Nufern and off-resonant pumping fiber. We also show that further no longer limited ytterbium parasitic lasing but fuse

Transverse mode instability is a key limit to power scaling of high-power fiber lasers. Accurate modeling efforts have, however, been hampered by lack experimental data verify model. Recently, there have some good studies, making it possible validate In this work, we developed model integrating 3D amplifier and stimulated thermal Rayleigh scattering. Since are only interested in the regime where fundamental dominates, our divides core into many cylindrical shells. This limits situations...

Fabrication process of efficient Yb/sup 3+/,Er/sup 3+/ codoped phosphosilicate fibers by modified chemical vapor deposition (MCVD) combined with the solution doping technique is studied in detail. We show that can be adapted to incorporate low viscosity phosphate glass and some important issues fabrication are discussed. These include sensitive presintering pass. also report on a loss all-glass double clad 3+/:Er/sup fiber. explain how we evaluate discuss effect ytterbium erbium...

We demonstrate that appropriately designed doped multimode fibers provide robust single-mode output when used within a fiber laser cavity. Using novel large-mode-area fiber, we what believe to be record (M(2) <1.2) pulse energies of >0.5 mJ from Q -switched and even higher (as high as 0.85 mJ) with slightly compromised spatial-mode quality (M(2)<2.0) . This approach offers significant scope for extending the range powers are achievable fiber-laser-amplifier systems.

A novel, temperature-independent strain sensor is demonstrated using a chirped fibre grating in tapered optical fibre. The effective bandwidth of the uniquely dependent on and essentially temperature-independent. interrogation simply involves monitoring back-reflected intensity from grating. resolution 0.1% over measurement range 4066 µɛ has been experimentally achieved.

For the first time production of Bragg fibre gratings written by single excimer laser pulses as is being drawn demonstrated. Reflectivities approaching 100% have been obtained, demonstrating feasibility online mass production.

We have demonstrated a novel add/drop filter for use in wavelength-division-multiplexing (WDM) optical fiber systems based on Bragg grating assisted mismatched coupler. The device is potentially easy to fabricate and stable, because it not interferometric, unlike all similar devices so far, and, therefore, does need fine tuning of the interferometers during fabrication maintain balance its lifetime.

Phosphorus co-doping is known to reduce clustering levels of rare earth ions in silica hosts. In this paper, ytterbium-doped fibers with approximately 8.9 wt% Yb(2)O(3), up 4700 dB/m peak core absorption at 976 nm, and low photo-darkening are demonstrated using high phosphorus co-doping. Measured gain as 7 dB/cm the fiber.

All glass leakage channel fibers have been demonstrated to be a potential practical solution for power scaling in fiber lasers beyond the nonlinear limits conventional large mode area fibers. The all nature with absence of any air holes is especially useful allowing used and fabricated much like Previously, double clad active low index polymer as pump guide drawbacks being less reliable at high powers not able change outer diameter independent dimension. In this work, we demonstrate, first...

Using an all-fiber laser system consisting of a femtosecond Er/Yb fiber oscillator as the pump and ultra-highly nonlinear for Stokes generation, we demonstrate multimodal (TPF+SHG+CARS) optical microscopy both tissue samples live cells.Multimodal imaging was successfully performed with pixel dwell times short 4 μs at low powers (< 40 mW total).

We present detailed studies of the coherence properties an ultrabroadband supercontinuum, enabled by a comprehensive approach involving continuous-wave laser sources to independently probe both amplitude and phase noise quadratures across entire spectrum. The continuum coherently spans more than 1.5 octaves, supporting Hz-level comparison ultrastable lasers at 698 nm 1.54 $\ensuremath{\mu}$m. complete numerical simulation accumulated comb in limit many pulses, contrast single-pulse level,...