Laser Terms -Nd:YAG A solid-state laser of the synthetic material Neodymium:Yttrium-Aluminum Garnet, producing a pulse at 1064 nm. -Nd:YLF A solid-state laser composed of Neodymium: Yttrium Lithium Fluoride. This lasing medium produces a pulse at 1054 nm. It is often doubled to 527 nm (IR to green) -Ti:Sapphire A solid-state laser composed of a titanium: Sapphire crystal, with tunable wavelengths between 750 nm and 850 nm. Well suited for pulsed or continuous-wave operation. -Mode-locking Superimposing light waves so they all have maximum peaks at a given point in space time. Optical parametric amplification (OPA) Terms Signal converted from pump 800 nm beam, output tunable from 1150 nm to 1600 nm Idler converted from pump 800 nm beam, output is tunable from 1600 nm to 2630 nm. Sum frequency generation (SFG) An input of two frequencies has an output with a frequency of their sum Difference frequency generation (DFG) An input of two frequencies has an output with a frequency of their difference Second harmonic generation (SHG) An input of a given frequency has an output of twice that frequency Fourth harmonic generation (FHG) An input of a given frequency has an output of four times that frequency Pulse compression A technique used to achieve higher peak power by narrowing the pulse width and therefore increasing the frequency bandwidth of the output of a laser. Group velocity dispersion (GVD) Timewise spreading of a pulse due to different frequencies of light traveling at different velocities through a medium. Spectroscopy terms Monochromator An instrument used to amplify and isolate a specific narrow region of the spectrum for analysis. Delay line A device used to delay transmission of a signal by making the path of one beam longer in relation to another. Absorption spectroscopy Study of the energies / wavelengths of radiation absorbed by molecules. Diffuse reflectance spectroscopy Study of ratio of diffusely reflected flux compared with incident flux. The diffusely reflected photons will give information about the structure of the molecule. Infrared spectroscopy Substance will absorb light in the infrared region corresponding to a change in the vibrational energy of the bonds. These peaks will identify what bonds are present in a molecule. Raman spectroscopy From the Raman effect, which states that when radiation passes through a medium, any light that passes through with a wavelength different from the wavelength of incidence is attributable to a change in the quantized vibrational energy of the medium Stimulated Raman spectroscopy Raman spectroscopy where the sample is provided with two sources of excitation: the primary pump and a beam of light at the wavelength of the inelastically scattered photons |