Optical pumping solid state

Photons Photoluminescence Fluorescent lamps, phototherapy lamps, light source, highlighting paints and inks, image intensifier, PLLCD, PDF and other display devices, optically pumped solid-state lasers, up conversion lasers, luminescent solar concentrators, diagnosis... 

Rare earths have found their widest application in optically-pumped solid-state lasers. Of the different transition metal ion groups which fluoresce in solids and which are thereby candidates for stimulated emission, the rare earths predominate. Ions used for crystalline lasers are listed in fig. 35.1 together with the number of crystal hosts which have been employed for each ion through 1975. Of the approximately 200 crystalline lasers reported, all are based upon rare earths except for a few iron group ions and one actinide ion. 

Trivalent lanthanide ions are used extensively for optically-pumped solid-state lasers because they possess suitable absorption bands and numerous fluorescence lines of high quantum efficiency in the visible and near-infrared. Figure 35.11 summarizes the energy levels, transitions, and approximate wavelengths of trivalent lanthanide ion lasers. In cases where the transitions are to Stark levels of the ground /-state manifold, operation at low temperatures is usually required. The number of different crystalline hosts in which each ion has lased is indicated in fig. 35.1. For several ions, stimulated emission has been observed between more than one pair of / states. A frequency-selective element (e.g., prism, grating, filter) is usually added to the resonator cavity to accomplish this. 

Optically pumped solid-state Ruby, Nd + YAG, Nd + glass, Cr + BeAl204 (alexandrite), Ti + Al203 (sapphire) ... 

The fast kinetics of the photoluminescence emission, picosecond and femtosecond relaxation, in ladder-type polyparaphenylenes is notable [142,143,186], since such measurements reveal stimulated emission and therefore promising aspects for LPPPs as a suitable material for optically pumped solid-state homopolymer lasers as well as for the realization of electrically pumped solid-state polymer lasers [144]. To illustrate the situation we depict the photoluminescence intensity as a function of the excitation power (excitation wavelength A = 295 nm) for... 

Fig. 5.5 Experimental setup. The diode laser is frequency scanned by one waveform generator, while the other controls the modulation. The light couples from a tapered fiber into and back out of microsphere WGMs, and the throughput is detected. A polarizing beamsplitter (PBS) separates throughput of the two polarizations. A diode pumped solid state laser can be used as an external heat source for the microsphere, and the vacuum chamber allows control over the ambient pressure. Reprinted from Ref. 5 with permission. 2008 International Society for Optical Engineering...

Raman Spectra. A Raman spectrum of the x XePtFg prepared in aHF, was recorded with a Halo Probe VPT System spectrometer (Kaiser Optical System, Inc., Ann Arbor, MI) using the 532 nm radiation of a Diode-Pumped, Solid-State (DPSS) Laser as exciting wavelength. It consisted of three lines at 657 cm (vs), 591 cm (s) and 480 cm (w). 

Summary Optical parametric oscillators are coherent devices similar to lasers. There are, however, important differences. While lasers can be pumped by incoherent sources, OPOs require coherent pump sources. Often diode laser-pumped solid state lasers are used. While in lasers coherent amplification can last until the inversion in the active medium has fallen below threshold, in OPO s the time dependence of the coherent output is directly coupled to that of the pump laser. Since the pump photon is split into signal and idler photon with u> = u>i, the energy of the output equals that of the input i.e. there is no energy, i.e. heat deposited in the active crystal. The spectral tuning range is by far wider than for tunable lasers. Most OPOs operate in the near infrared but can be tuned from the visible region to the far infrared. 

M. Ebrahimzadeh, G.P.A. Malcolm, and A.I. Eerguson, Continuous-Wave Mode-Locked Optical Parametric Oscillator Synchronously Pumped by a Diode-Laser-Pumped Solid-State Laser , Opt. Lett. 17, 183 (1992). 

Figure 5.28 Upper experimental setup [40], Lenses LI and L2 are used to expand a plane wave, and D is a diaphragm. Lenses L3 and L4 are the transformation lenses, A is an analyzer, and DPSS a diode-pumped solid-state laser. The DDLC sample is placed in the transform plane. Sc is the command surface that changes the orientation of the photosensitive dye absorbed on it Sg is the reference surface with rubbed and fixed LC alignment. Lower the object (a grating mask with 25 mm spacing) is a periodic step function that produces numerous diffracted orders after Fourier transformation LI, lens. Reproduced from T.-H. Lin and A. Fuh, Polarization controllable spatial filter based on azo-dye-doped liquid-crystal film. Optics Letters 30, 1390 (2005), Optical Society of America...

These limitations have recently been eliminated using solid-state sources of femtosecond pulses. Most of the femtosecond dye laser teclmology that was in wide use in the late 1980s [11] has been rendered obsolete by tliree teclmical developments the self-mode-locked Ti-sapphire oscillator [23, 24, 25, 26 and 27], the chirped-pulse, solid-state amplifier (CPA) [28, 29, 30 and 31], and the non-collinearly pumped optical parametric amplifier (OPA) [32, 33 and 34]- Moreover, although a number of investigators still construct home-built systems with narrowly chosen capabilities, it is now possible to obtain versatile, nearly state-of-the-art apparatus of the type described below Ifom commercial sources. Just as home-built NMR spectrometers capable of multidimensional or solid-state spectroscopies were still being home built in the late 1970s and now are almost exclusively based on commercially prepared apparatus, it is reasonable to expect that ultrafast spectroscopy in the next decade will be conducted almost exclusively with apparatus ifom conmiercial sources based around entirely solid-state systems. 

Por IR-Raman experiments, a mid-IR pump pulse from an OPA and a visible Raman probe pulse are used. The Raman probe is generated either by frequency doubling a solid-state laser which pumps the OPA [16], or by a two-colour OPA [39]. Transient anti-Stokes emission is detected with a monocliromator and photomultiplier [39], or a spectrograph and optical multichannel analyser [40]. 

The term solid-state laser refers to lasers that use solids as their active medium. However, two kinds of materials are required a host crystal and an impurity dopant. The dopant is selected for its ability to form a population inversion. The Nd YAG laser, for example, uses a small number of neodymium ions as a dopant in the solid YAG (yttrium-aluminum-gar-net) crystal. Solid-state lasers are pumped with an outside source such as a flash lamp, arc lamp, or another laser. This energy is then absorbed by the dopant, raising the atoms to an excited state. Solid-state lasers are sought after because the active medium is relatively easy to handle and store. Also, because the wavelength they produce is within the transmission range of glass, they can be used with fiber optics. 

Four different types of tasks are performed by automation. Two involve the sequencing of valves and pumps Involved 1n the setup and completion of the designed experiment through the operation of the test and hydraulic fluid systems. The other tasks involve the control of the temperature bath and data collection. To perform these tasks, a1r-actuated solenoids and optically coupled sol Id-state relays are used. These devices are controlled by an electrical circuit consisting of the device connected 1n series with a power supply and a channel on the actuator card In the HP 3497. The power supply 1s either 24 VDC for use with the solenoids or 5 VDC for the solid-state relays. The actuator output channel acts as a simple on/off switch which allows power to be supplied to the solenoid or relay when closed. The logic of the circuit 1s controlled by application programs running on the local HP 1000. 

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