A three-color, solid-state, volumetric display based on two-step, two-frequency upconversion in rare earth-doped heavy metal fluoride glass is described. The device uses infrared laser beams that intersect inside a transparent volume of active optical material to address red, green, and blue voxels by sequential two-step resonant absorption. Three-dimensional wire-frame images, surface areas, and solids are drawn by scanning the point of intersection of the lasers around inside of the material. The prototype device is driven with laser diodes, uses conventional focusing optics and mechanical scanners, and is bright enough to be seen in ambient room lighting conditions. QuickTime movie of the three-dimensional display.

https://science.sciencemag.org/content/sci/273/5279/1185.full.pdf

A Three-Color, Solid-State, Three-Dimensional Display

Fibre lasers in the mid-infrared regime are useful for a diverse range of fields, including chemical and biomedical sensing, military applications and materials processing. This Review summarizes the different rare-earth cations and host materials used in mid-infrared fibre laser technology, and discusses the future applications and challenges for the field.

Towards high-power mid-infrared emission from a fibre laser

The invention provides methods, compositions, and apparatus for performing sensitive detection of analytes, such as biological macromolecules and other analytes, by labeling a probe molecule with an up-converting label The up-converting label absorbs radiation from an illumination source and emits radiation at one or more higher frequencies, providing enhanced signal-to-noise ratio and the essential elimination of background sample autofluorescence The methods, compositions, and apparatus are suitable for the sensitive detection of multiple analytes and for various clinical and environmental sampling techniques

Up-converting reporters for biological and other assays using laser excitation techniques

Ytterbium-doped silica fibers exhibit very broad absorption and emission bands, from /spl sim/800 nm to /spl sim/1064 nm for absorption and /spl sim/970 nm to /spl sim/1200 nm for emission. The simplicity of the level structure provides freedom from unwanted processes such as excited state absorption, multiphonon nonradiative decay, and concentration quenching. These fiber lasers therefore offer a very efficient and convenient means of wavelength conversion from a wide variety of pump lasers, including AlGaAs and InGaAs diodes and Nd:YAG lasers. Efficient operation with narrow linewidth at any wavelength in the emission range can be conveniently achieved using fiber gratings. A wide range of application for these sources can be anticipated. In this paper, the capabilities of this versatile source are reviewed. Analytical procedures and numerical data are presented to enable design choices to be made for the wide range of operating conditions. >

/pdf/ytterbium-doped-silica-fiber-lasers-versatile-sources-for-qjavzdlo6k.pdf

Ytterbium-doped silica fiber lasers: versatile sources for the 1-1.2 /spl mu/m region

We review the recent progress of information theory in optical communications, and describe the current experimental results and associated advances in various individual technologies which increase the information capacity. We confirm the widely held belief that the reported capacities are approaching the fundamental limits imposed by signal-to-noise ratio and the distributed non-linearity of conventional optical fibres, resulting in the reduction in the growth rate of communication capacity. We also discuss the techniques which are promising to increase and/or approach the information capacity limit.

/pdf/approaching-the-non-linear-shannon-limit-1c8ubzq84k.pdf

Approaching the Non-Linear Shannon Limit

Continuous-wave, room temperature laser oscillation at 491 nm, 520 nm, 605 nm and 635 nm in a Pr3+-doped fluoro-zirconate fibre pumped simultaneously at 1.01 µm and 0.835µm is reported. An output power of 185mW has been measured for the 635 nm transition. The thresholds obtained suggest that laser diode-pumped operation of all four transitions should be possible in an optimised fibre.

/pdf/cw-room-temperature-upconversion-lasing-at-blue-green-and-2586ih5o10.pdf

CW room temperature upconversion lasing at blue, green and red wavelengths in infrared-pumped Pr3+-doped fluoride fibre

The OH fundamental peak absorption at 2.87 μm has been reduced in fluoride fibres to less than 20 dB/km. By measuring the difference spectra between low and high peaks, the OH-peak shape has been measured over two orders of magnitude, and the results indicate that the optimum low-loss window occurs at 2.55 μm in these materials.

OH-absorption in fluoride glass infra-red fibres

Gain of 10.5 dB has been achieved at a wavelength of 1.3 μm, by using a 17 m length of single mode fluorozirconate fibre doped with 560 ppmw Pr3+, and pumped at 1.007 μm. The gain increased almost linearly with launched pump power, with a slope efficiency of 0.019 dB/m W.

Amplification at 1.3 μm in a Pr3+-doped single-mode fluorozirconate fibre

Gain values of 4 to 5 dB were observed between 1310 and 1370 nm in a Nd-doped bimoded ZBLAMP fibre pumped at the diode laser compatible wavelength of 795 nm. The magnitude of the gain was shown to be limited by saturation due to amplified spontaneous emission from 1050 nm radiation. The excited state absorption spectrum was mapped.

Amplification in the 1300 nm telecommunications window in a Nd-doped fluoride fibre

A major cause of loss in fluoride fibres has been extrinsic scatter from bubbles trapped in preforms during casting. A new reduced pressure casting (RPC) technique has been developed to eliminate bubbles, and the minimum fibre loss has been reduced to 0.65 ± 0.25 dB/km at 2.59 μm, measured over a 110 m length of fibre.

S.F. Carter

Papers

CW room temperature upconversion lasing at blue, green and red wavelengths in infrared-pumped Pr3+-doped fluoride fibre

OH-absorption in fluoride glass infra-red fibres

Amplification at 1.3 μm in a Pr3+-doped single-mode fluorozirconate fibre

Amplification in the 1300 nm telecommunications window in a Nd-doped fluoride fibre

Low loss fluoride fibre by reduced pressure casting