Infrared Laser Light Research Articles

Driven Morse oscillator: The quantum problem simplified

The driven Morse oscillator in quantum formulation is a good model for the analysis of molecular dissociation by infrared laser light. A method is presented to transform the time-dependent Schrödinger equation of the system, by a Green’s function procedure, into a first-order Fredholm integral equation, more amenable to numerical solution.

Nonlinear phenomena induced by infrared laser light

Different nonlinear phenomena arised at IR laser-solid interaction at existence of positive feedback between the “thermal’ and “chemical” degrees of freedom of the system through the change of absorption characteristics of the target are discussed. It is shown experimentally that varying the control parameters ( P m , where P = power of the light, m= mass of the target) different spatio-temporal structures such as, periodical-, stochastic- and autooscillations of thermal field on the irradiated surface due to CW and pulsed IR lasers could be registered (which could be described by s.c. order parameters). The observed events of self-organization types are explained in frames of theory of instabilities connected with temperature dependence of surface tension of melted material and temperature gradient caused Rayleigh like convections.

Harmonic and sum-frequency generation of pulsed laser radiation in BBO, LBO, and KD*P

The optical properties of the nonlinear crystals lithium borate (LBO), barium borate (BBO) and deuterated potassium phosphate (KD*P) are compared for second and third harmonic generation of Nd:YAG laser radiation. In an experimental investigation the conversion efficiency has been measured as a function of the energy density of 8 ns long laser pulses, generated by a commercial Nd:YAG oscillator-amplifier system. In LBO and BBO the second harmonic generation saturates at an energy density of about 1.5 J cm−2 at efficiencies of 55–60%. In KD*P comparable efficiencies (40–55%) require energy densities of 2–2.6 J cm−2. Similar results are obtained for frequency tripling. In LBO and BBO saturated efficiencies of 20–25% are measured at an energy density of about 1.5 J cm−2. In KD*P efficiencies of 20% are obtained at energy densities exceeding 2 J cm−2. Besides for doubling and tripling of Nd:YAG laser radiation the phase-matching is calculated for frequency conversion of tunable laser light. The results demonstrate that in LBO and BBO phase-matched sum-frequency mixing of UV and infrared laser light generates tunable radiation at wavelengths as short as the transmission cut-off at 160 nm and 190 nm, respectively.

Pulsed laser-induced SEU in integrated circuits: a practical method for hardness assurance testing

A pulsed picosecond laser was used to measure the threshold for single event upset (SEU) and single event latchup (SEL) for a detailed study of a CMOS SRAM and a bipolar flip-flop. Comparing the ion and laser upset data for two such vastly different technologies gives a good measure of how versatile the technique is. The technique provided both consistent and repeatable results that agreed with published ion upset data for both types of circuits. However, measurements of the absolute threshold linear energy transfer (LET) using infrared laser light do not agree with those of the ions, being about 50% too high for the SRAMs, and about 20% too high for the bipolar flip-flops. The consistency of the results, together with the advantages of using a laser system, suggests that the pulsed laser can be used for SEU/SEL hardness assurance of integrated circuits. >

Collision dynamics of OH(X 2Πi,v=12)

Collisional removal rate constants for the OH radical in v=12 of the ground electronic state are measured for the colliders CO2, O2, N2, H2, He, and Ar. OH molecules, generated in v=8 by the reaction of hydrogen atoms with ozone, are excited to v=12 by direct overtone excitation with pulsed infrared laser light. The temporal evolution of the v=12 radicals is probed as a function of collider gas pressure by a time-delayed pulsed ultraviolet probe laser. The probe laser is used to excite the molecules via the B 2Σ+–X 2Πi(0,12) electronic transition, and the resulting B 2Σ+–A 2Σ+ fluorescence is detected. We measure rate constants for CO2:(5.6±1.5)×10−11; O2:(1.6±0.2)×10−11; He:(3.6±0.6)×10−12; H2:(3.0±0.8)×10−12; Ar:(2.6±0.5)×10−12; N2:(2.5±0.7)×10−12 (all in units of cm3 s−1). These rate constants are over fifty times faster in all cases than the vibrational relaxation rate constants for the lower levels (v=1 and v=2) of the ground state.

Laser double-resonance study of OH ( X2Π i, v = 12)

The spectroscopy of OH ( X 2Π i , v = 12) is examined using a two-laser double-resonance method. OH molecules generated in v = 8 by the reaction of hydrogen atoms with ozone are excited by pulsed tunable infrared laser light via direct overtone excitation to v = 12. The absorption is monitored either by a depletion in B 2Σ +- X 2Π i laser-induced fluorescence (LIF) signals on the (0, 8) band or by an observation of LIF signals on the B- X (0, 12) band. Line positions for X- X (12, 8) and B- X (0, 12) are reported. The relevance of these measurements to spacecraft glow and ab initio theoretical calculations is discussed.

Deposition of nickel microstructures by CO2 laser-assisted decomposition of nickel tetracarbonyl

Nickel microstructures were produced from decomposition of Ni(CO)4 on quartz plates locally heated with a focused cw CO2 laser beam operating at 10.59 μm. The profile and deposition rate of Ni dots were determined as functions of irradiation time, reactant pressure, laser power, and laser-induced surface temperature. The kinetic data were found to be in good agreement with those of the visible laser-induced chemical vapor deposition (CVD) of Ni dots and CVD of Ni films in furnace-type CVD reactors. The decomposition of Ni(CO)4 molecules irradiated with the infrared laser light occurred via a purely thermal process.

Investigations of the preparation process for efficient second-harmonic generation in optical fibers

Experiments were carried out to elucidate aspects of the preparation process, which enables glass fibers to efficiently frequency-double infrared laser light. A picture is described which is consistent with most of the observations.

Resonance-enhanced multiphoton ionization of vibrationally excited state-selected NH 3. Spectroscopy and collisional state transfer

Infrared laser light prepares X̃-state NH 3 in selected JK levels of the ν 3+ν 4 combination vibration. Ultraviolet laser light perfo 2+1 REMPI on those states. This is used to detect those states and thereby carry out state-to-state collision experiments, and to find previously unobserved vibrational levels (i.e. ν 4 and ν 3+ν 4) of the B̃ Rydberg state.

Evaluation of an infrared laser-Doppler blood flowmeter.

Several laser-Doppler blood flowmeters are now commercially available; however, only one utilizes an infrared laser diode (Laserflo, TSI, St. Paul, MN). Because of this and other unique features such as its microprocessor-based signal analyzer, we evaluated this device's ability to measure tissue perfusion. Initially, we determined whether laser illumination directly affected the microvasculature. Intravital microscopic observations in the hamster cremaster muscle indicated that neither He-Ne nor infrared laser light affected the diameters of arterioles that were responsive to vasoactive agents. To test the flowmeter for linearity and repeatability, we used a rotating disk to simulate a light-scattering, flowing medium. The "flow" signal was highly correlated (r = 0.99) with the rotational velocity of the disk, was consistent among flow probes, and showed a high degree of reproducibility. The second model consisted of microsphere suspensions pumped through cuvettes. The laser-Doppler velocimeter (LDV) flow signal was linear with respect to pump output. With red blood cells in the perfusate, we examined the effects of blood oxygenation on the flowmeter's performance. The LDV flow signal was unaffected by changes in blood oxygenation. We evaluated linearity in vivo in isolated, perfused rat livers and in isolated canine gastric flaps. We observed linear relationships between total flow and laser-Doppler flow measured on the surface of the liver (r = 0.98) and in the gastric mucosa (r = 0.98), but the slopes of the relationships between total and local LDV flow showed considerable variability not noted in the in vitro studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Infra-red light modulator of ridge-type optical waveguide structure using effect of free-carrier absorption

An experimental study of optical modulation of 10.6 μm infra-red CO2 laser light using the effect of free-carrier absorption is performed. The modulator has a ridge-type optical waveguide structure having the electrodes for the carrier injection. In this modulating electrode, the tunnel MIS structure is used because it can effectively inject the minority carrier. It becomes clear that a fairly high degree of modulation up to 62% can be realised by such a structure.

Instability of polaritons driven by infrared laser light

In the present paper the nonlinear behavior of lattice vibrations driven by a coherent electromagnetic wave on the basis of Huang's equations is discussed. Under certain conditions formulated in the text these mixed electromagnetic lattice waves (polaritons) become unstable for some regions of the parameters of the incident laser light. Unstable motion of crystal lattices may be considered as a damage mechanism of the crystal structure.

Multiple‐Photon Infrared Laser Photophysics and Photochemistry. I

This paper begins our review paper on the multiple-photon excitation of molecules by intense infrared laser light. The whole review will be given in installments. In this first part we bring forward certain general concepts on spectroscopy, molecular physics and chemical kinetics essential for understanding the later material.

Photochemistry in the electronic ground state. Isotope separation by infrared multiphoton isomerization of complex molecules

Isotope selective isomerization of hexafluorocyclobutene to hexafluorobutadiene by multiphoton absorption of infrared laser light has been studied. All the three possible isotopomers were separated. The wavelength dependence of the reactions, saturation of absorption and the role of inert gas in retaining the selectivity are described.

Thermal field emission as a mechanism for infrared laser light detection in metal whisker diode

The non-linear current-voltage characteristic of thermally enhanced field emission is proposed to explain the operation of a metal-metal point contact diode used for laser harmonic frequency generation and frequency mixing in the infrared region. This mechanism can explain several experimental observations which appear inconsistent with the previous analysis based on a planar metal-oxide-metal tunneling geometry.

High-Resolution Atmospheric-Transmission Measurement Using a Laser Heterodyne Radiometer

Laser heterodyne technology is a highly sensitive laser spectroscopy technique which can be integrated. It has the potential to develop a compact ground or satellite based radiometer for Earth observation and astronomy. Based on the laser heterodyne technology, a set of high resolution laser heterodyne detection system was established together with a solar tracker. The spectral resolution of the system is about 0.006 cm(-1). Sunlight is superimposed with infrared laser light in a nonlinear detector. The signals pass through an electronics filter and a square-law detector, then the high-resolution heterodyne signal is extracted. In terms of the field measurement, Langley-Plot Calibration method was used to calibrate the system first, then total atmosphere transmittance of mid-infrared was measured. The calibration constant and corresponding to the atmospheric total optical thickness were presented. According to the comparison between the results of heterodyne measurement system and that of software MORTRAN5. 0 calculation, good agreement was obtained. It is shown that the system has high spectral resolution which can be applied to atmospheric transmittance measurement. Besides, the system also shows potential applications in atmospheric sciences, astronomy, laser propagation through the atmosphere and other areas.

OPTICAL PROBING OF MAGNETOSTATIC MODES IN YIG DELAY LINES

Diffraction of infrared laser light from magnetostatic modes in yttrium iron garnet has been used to study the mechanism by which electromagnetic energy, fed to a grounded wire antenna at one end of an axially magnetized crystal, is converted to exchange-spin-wave energy. The properties exhibited by the diffraction support the theory in detail.