Abstract: Methods for cooling fluorescent material are provided. A first method includes providing a sample of the material having an elongated direction of light propagation, exhibiting fluorescence at a mean fluorescence wavelength and capable of emitting superradiant pulses with a formation delay time. The method then involves generating a pump pulsed laser beam having a wavelength longer than the mean fluorescence wavelength, a pump power at which superradiant pulses are emitted and a pulse duration shorter than the formation delay time. The pulses are directed onto the sample along the direction of light propagation to produce the superradiant pulses in an anti-Stokes process inducing a cooling of the sample. A second laser cooling method includes a combination of a traditional anti-Stokes cooling cycle and an upconversion cooling cycle, wherein the two cooling cycles act cooperatively to cool the sample.

Abstract: Fiber light amplifiers adapted for high power application are provided. In embodiments of the invention, the light signal to be amplified is coupled to a cladding mode of an active waveguide region which is cladding doped. The amplified light is coupled to an output fiber have waveguiding properties matching those of the active cladding of the active waveguide region. In other embodiments, two or more amplifying stages are provided coupled by a wavelength selective loss element which couples the Stokes wave co-propagating with the signal to be amplified out of the signal guiding mode prior to the onset of SRS.

Abstract: The invention relates to optical sensors and systems and methods employing the sensors for detecting one or more compounds of interest in a test medium. In one embodiment an optical sensor comprising a long period grating and a solid phase microextraction (SPME) film is exposed to a test medium such that one or more compounds of interest are selectively partitioned into the solid phase microextraction film. At least one optical property of the sensor exposed to the test medium is compared with at least one corresponding optical property of the sensor in absence of the test medium; wherein a difference in the optical property is indicative of one or more compounds of interest in the test medium. The methods and systems may employ long period grating sensors with or without SPME films, and fiber loop ring-down spectroscopy to measure optical properties of the sensor.

Abstract: The invention relates to optical sensors and systems and methods employing the sensors for detecting one or more compounds of interest in a test medium. In one embodiment an optical sensor comprising a long period grating and a solid phase microextraction (SPME) film is exposed to a test medium such that one or more compounds of interest are selectively partitioned into the solid phase microextraction film. At least one optical property of the sensor exposed to the test medium is compared with at least one corresponding optical property of the sensor in absence of the test medium; wherein a difference in the optical property is indicative of one or more compounds of interest in the test medium. The methods and systems may employ long period grating sensors with or without SPME films, and fiber loop ring-down spectroscopy to measure optical properties of the sensor.