Kigre (United States)

LIBS (Laser Induced Breakdown Spectroscopy) systems are capable of real-time chemical analysis with little or no sample preparation. A Q-switched laser is configured such that laser induced plasma is produced on targeted material. Chemical element line spectra are created, collected and analyzed by a fiber spectrometer. Line spectra emission data is instantly viewed on a head mounted display. "Eye-safe" Class I erbium glass lasers provide for insitu LIBS applications without the need for eye-protection goggles. This is due to the fact that Megawatt peak power Q-switched lasers operating in the narrow spectral window between 1.5um and 1.6um are approximately 8000 times more "eye-safe" than other laser devices operating in the UV, visible and near infrared. In this work we construct and demonstrate a LIBS system that includes a hand held eye-safe laser gun. The laser gun is fitted with a micro-integrating sphere in-situ target interface and is designed to facilitate chemical analysis in remote locations. The laser power supply, battery pack, computer controller and spectrophotometer components are packaged into a utility belt. A head mounted display is employed for "hands free" viewing of the emitted line spectra. The system demonstrates that instant qualitative and semi-quantitative chemical analyses may be performed in remote locations utilizing lightweight commercially available system components ergonomically fitted to the operator.

We present a new method based on thermal lens (TL) technique to determine the fluorescence quantum efficiency, $\ensuremath{\eta}$, and thermo-optical coefficients of fluorescent materials. These parameters can be obtained from the linear dependence of the TL signal with the experimental lifetimes of a set of samples with different luminescent ion concentrations. The method was applied in ${\mathrm{Nd}}^{3+}$-doped materials (Q-98 Phosphate, fluorozirconate, and fluoroindate). The obtained values are in agreement with those determined by other approaches based on TL methods and the ratio between experimental and radiative lifetime values (Judd-Ofelt theory). The method hereafter presented is very simple and does not require comparison with a reference sample or the use of multiple excitation wavelengths. In addition, the nature of concentration quenching taking into account the achieved $\ensuremath{\eta}$ and $\ensuremath{\tau}$ values and respective energy transfer microparameters, is discussed.

We established a new diode array pumped Er:Yb:Glass test setup for evaluation of the laser performance and q-switch characteristics of various saturable absorber materials at 1.54micrometers . Pumping distribution and maximum gain was analyzed. Passive q-switched laser operation was demonstrated with both U<SUP>2+</SUP>:CaF<SUB>2</SUB> and CO<SUP>2+</SUP>:MgAl<SUB>2</SUB>O<SUB>4</SUB>. TEMoo Q-switch pulses with energy of 0.5mJ and pulse width of 10ns was obtained.

High power, high brightness fiber lasers have numerous potential commercial and military applications. Fiber lasers with cladding pump designs represent a new generation of diode pumped configurations that are extremely efficient, have single mode output and may be operated with or without active cooling. Kigre has invented a new family of Er/Yb/Nd phosphate laser glass materials (designated QX) that promise to facilitate a quantum leap in fiber laser technology of this field. The new phosphate glass Rare-Earth doped fiber exhibit many advantages than Silica or Fluoride base fiber, see table.1. Instead of 30 to 50 meters of fused silica with a 50 mm bend radii; Kigre's phosphate glass fiber amplifiers may be designed to be less than 4 meters long .Laser performance and various design parameters, such as the fiber core diameter, NA, inner cladding shape and doping concentration are evaluated. Laser performances was demonstrated for an experimental QX/Er doubled clading fiber commissioned by MIT having 8 micron core, a 240 X 300 micron rectangle shaped inner cladding with 0.4 NA and 500 micron outer clading.. Kigre obtained approximately 2 dB/cm gain from 15cm long fiber under 940nm pumping The same fiber was evaluated by researcher at MIT. They used 975nm pump source. Maximum 270mW output was demonstrated by 30 cm long fiber with Fresnel reflection resonator mirrors. The slope efficiency of absorbed pump power s 47%.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

High power, high brightness fiber lasers have numerous potential commercial and military applications. These lasers offer unique flexibility as they may be coherently combined to provide a potential multi-kilowatt laser source and integrated delivery system. Fiber lasers with cladding pump designs represent a new generation of diode pumped configurations that are extremely efficient, have single mode output and may be operated with or without active cooling. They have a number of novel or unusual attributes, stemming from the fact that they represent the extreme case of a long gain length thin laser cavity. Reports indicate that over 100 watts of TEM00 CW output power are readily demonstrated from current cladding pumped fiber laser designs. [1,2]

A new Er 3+ doped phosphate glass exhibiting an excellent durability in both boiling water and NaNO 3 molten salt was developed. Ion-exchange process of this glass was investigated by treating glass samples in a variety of salt bathes with various exposure times. Planar waveguide with one mode at 1.54 micrometers and three modes at 632.8 nm was demonstrated. Spectral properties of Er 3+ in this glass were characterized by measuring absorption and emission spectra, and fluorescence lifetimes. Emission cross section of Er 3+ in this glass was calculated to be 0.76 X 10 -20 cm 2 using McCumber theory. Our preliminary experimental results indicate this new Er 3+ doped glass is an excellent material for ion-exchanged waveguide lasers and amplifiers.

New erbium doped glass base compositions and sensitizer ion concentrations have been investigated. Laser, spectral, and thermo-mechanical properties have been tested. This study has resulted in a new erbium doped phosphate laser glass that exhibits improved thermal shock resistance and superior laser performance.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new method which improves the laser drilling efficiency and allows for drilling at large laser-target standoff distances has been developed. A dual pulse laser was found to be capable of penetrating stainless steel targets with a thickness greater than 1/4” at standoff distances of 1 meter. The standoff distance is defined by the distance between the focusing lens and the target. The dual pulse laser produced two free-running laser pulses from a single Nd:glass or Nd:YAG laser head driven by integrated power supplies. The output consisted of the combination of a high energy, long duration pulse (pulse 1) with a high peak power laser pulse (pulse 2) fired at the end of pulse 1. Pulse 1 is used to produce a large molten pool of liquid which is expelled by the vapor recoil pressure generated by the interaction of the high intensity pulse 2 with the metal.A new method which improves the laser drilling efficiency and allows for drilling at large laser-target standoff distances has been developed. A dual pulse laser was found to be capable of penetrating stainless steel targets with a thickness greater than 1/4” at standoff distances of 1 meter. The standoff distance is defined by the distance between the focusing lens and the target. The dual pulse laser produced two free-running laser pulses from a single Nd:glass or Nd:YAG laser head driven by integrated power supplies. The output consisted of the combination of a high energy, long duration pulse (pulse 1) with a high peak power laser pulse (pulse 2) fired at the end of pulse 1. Pulse 1 is used to produce a large molten pool of liquid which is expelled by the vapor recoil pressure generated by the interaction of the high intensity pulse 2 with the metal.

Optical-absorption and emission spectra and fluorescence lifetimes were measured for Nd3+ in tellurite glasses containing various alkali and higher valence state cations and in a series of new phosphotellurite glasses. Judd-Ofelt intensity parameters were determined and used to calculate radiative lifetimes and stimulated emission cross sections for 4F3/2→4I11/2 and 4F3/2→4I13/2 transitions. Cross sections for several of the glasses are the largest obtained for any pure oxide glass. The dependence of the spectroscopic properties on composition and the application of tellurite glasses for lasers are discussed.