39 W narrow spectral linewidth monolithic ytterbium-doped fiber MOPA system operating at 976 nm.

We report on a monolithic narrow spectral linewidth master oscillator power amplifier (MOPA) delivering up to 39 W around 976 nm with very high contrast. The amplifier is based on an ytterbium-doped large mode area (LMA) octagonal double clad (DC) active fiber with parameters optimized for long living three-level operation.

Polymer micronozzle array for multiple electrosprays produced by templated synthesis and etching of microstructured fibers.

Microstructured fibers (MSFs) having raised polymer nozzles in each channel are custom designed, fabricated, and tested for use as multiple electrospray (MES) emitters for mass spectrometry (MS). There is strong motivation to develop electrospray emitters that operate at practical flow rates but give the much greater ionization efficiency associated with lower (nano) flow rates. This can be accomplished by splitting the flow into many lower-volume electrosprays, an approach known as MES. To couple with most modern mass spectrometers, the MES emitter must have a small diameter to allow efficient ion collection into the MS. In this work, a MSF, defined as a fiber having many empty channels running along its length, was designed to have 9 channels, 9 µm each, >100 µm apart arranged in a radial pattern, all in a fiber having a compatible diameter with both front-end LC equipment and typical MS inlets. This design seeks to promote independent electrospray from each channel while maintaining electric field homogeneity. While the MSFs themselves do not support MES, the formation of polymer nozzles protruding from each channel at the tip face enables independent electrospray from each nozzle. Microscope imaging, electrospray current measurement, and ESI-MS detection of a model analyte all confirm the MES behavior of the 9-nozzle emitter, showing significant signal enhancement relative to a single-nozzle emitter at the same total flow rate. LC/MS data from a protein digest obtained at an independent laboratory demonstrates the applicability and robustness of the emitter for real scientific challenges using modern LC/MS equipment.

Description of the response of a fiber optic velocity sensor applied to capillary gas chromatography.

This paper explores the response of a novel fiber optics sensor allowing real-time determination of the migration rate of vapor zones in capillary gas chromatography. The sensitivity is related to the gradient of the vapor zone distribution in the capillary and it is highest when vapor zones show steep variations in concentration. The expected linearity between the height of the velocity peaks and the response of a thermal conductivity detector is demonstrated experimentally. The sensor can be used to infer an approximate value of the analyte diffusion coefficient from the time response. Finally, the time evolution of the envelope of the optical signal is explained with experimental evidences.

Vapor zone velocities measurement using a capillary optical fiber sensor with an application to gas chromatography.

A fiber optic sensor has been used for real-time measurement of the migration rates of all the compounds in a mixture separated by gas chromatography. The sensor makes use of a coated capillary optical fiber as the column. This new type of waveguide consists in a polarization-maintaining optical core positioned close to the capillary edge along the entire fiber length. The optical detection is performed through the coupling of the two polarization modes of the waveguide and this coupling is detected by a polarimetric interferometry technique. Through some signal processing, the resulting interferogram provides the migration rates of the various compounds of a gas mixture flowing in the capillary. One of the major benefits of this optical migration rate sensing is that the detection of each velocity peak appears as soon as the analyte enters the capillary fiber and the peaks are constantly measured during the whole separation process. Carrier gas acceleration occurring in the column is plainly demonstrated. This paper presents a proof-of-concept on a qualitative basis. The experiments were done at 29 degrees C because the current opto-fluidic set-up cannot withstand a higher temperature.

Intensity and polarization dependences of the supercontinuum generation in birefringent and highly nonlinear microstructured fibers.

We present experimental results highlighting the physica mechanism responsible for the initial spectral broadening of femtosecond Ti:Sapphire pulses in a highly birefringent microstructured fiber having a small effective area. By rotating the input polarization and varying the injected power while monitoring the resulting changes in the output spectrum, we are bringing clear evidences that the initial broadening mechanism leading to a broadband supercontinuum is indeed the fission of higher-order solitons into redshifted fundamental solitons along with blueshifted nonsolitonic radiation.

Microstructured fiber splicing.

We present experimental results on Microstructured Optical Fiber (MOF) splicing with a simple method relying on conventional electric-arc splicers. The results are presented in terms of fusion losses and tensile strength. An electric-arc splicing system is used to demonstrate its effectiveness in splicing MOFs together as well as splicing MOF with a single mode fiber.