Tunable Visible Laser Research Articles

Tunable visible solid-state lasers based on intracavity frequency doubling of Cr:forsterite in KTP

Broadband tunability in the yellow-red region is obtained by use of intracavity type II second-harmonic generation of gain-switched Cr:forsterite lasers in KTiOPO(4) . An operating wavelength range of 67 nm, from 587 to 654 nm, is obtained. Second-harmonic energy of almost 1 mJ is achieved at a peak wavelength of 620 nm. A measured factor-of-34 enhancement in acceptance angle is obtained with broadband harmonic generation. Frequency doubling is optimized with respect to the Cr:forsterite pump and laser parameters.

Tunable visible solid-state lasers based on second-harmonic generation of LiF:F_2^- in potassium titanyl phosphate

A new broadly tunable visible solid-state laser is reported. Wavelengths between 550 and 610 nm are generated by intracavity frequency doubling of tuned and free-running room-temperature pulsed LiF:F(2)(-) lasers in potassium titanyl phosphate. Second-harmonic energy of 1.3 mJ has been achieved, corresponding to a fundamental-to-second-harmonic conversion efficiency of 20%. Operation is optimized with respect to LiF:F(2)(-) laser parameters.

Tunable visible laser based on a sapphire crystal with colour centres

An investigation was made of the optical stability of the active medium in the form of Al2O3 containing colour centres and subjected to two-channel laser pumping. This laser medium retained its high stability under the action of pumping in the 305 and 460 nm bands because of a dynamic balance between forward and reverse charge-transfer processes in the colour centres under two-stage ionisation conditions. An optical system was proposed and a stable tunable (in the green—orange range at 520–630 nm) laser was demonstrated.

High-intensity laser beam attenuation based on two-step absorption mechanism

Due to rapid progress in the development of high-power tunable visible lasers, it is expected that eye protection from tunable lasers in the open field will be needed in the near future. A nonlinear method is proposed that will transmit low-intensity light, but absorb light at high intensities. This high-intensity attenuator is based on the use of a liquid or solid made up of molecules having the property of undergoing two-photon photodissociation through most of the visible part of the spectrum. This material must also have the additional property that one of the products of the photodissociation is a one-photon absorber throughout the same wavelength region. It is suggested that the laser beam intensity can be attenuated by a large factor through these two-step absorption mechanisms, and that if the one-photon absorbing product is quenched by collisions with some component of the liquid in a time that is small compared with the laser pulse length, very large attenuation can be achieved from the built-up concentration of one-photon absorbers. Thus, the early part of a laser pulse is attenuated by two-photon absorption only, but the later parts of the pulse can be attenuated by factors as large as 105. Using a double-pass geometry, the leading edge of the pulse can be absorbed by linearly absorbing species formed on the first pass. The double-pass method, with an optical delay line, can even work well with picosecond pulses.

Proposed UV FEL user facility at BNL

The NSLS at Brookhaven National Laboratory is proposing the construction of an UV FEL operating in the wavelength range from visible to 1000 Å. Nanocoulomb electron pulses will be generated at a laser photocathode rf gun at a repetition rate of 10 kHz. The 6 ps pulses will be accelerated to 250 MeV in a superconducting linac. The FEL consists of an exponential growth section followed by a tapered section. The amplifier input is a harmonic of a tunable visible laser generated either by nonlinear optical material or the nonlinearity of the FEL itself. The FEL output in 10 −4 bandwidth is 1 mJ per pulse, resulting in an average power of 10 W. The availability of radiation with these characteristics would open up new opportunities in photochemistry, biology and nonlinear optics, as discussed in a recent workshop held at BNL.

Resonant two-photon dissociation of Ni 2+

Ni 2 + ions generated in a pulsed high-temperature plasma and cooled by supersonic expansion are photodissociated with tunable visible laser radiation. Resonant bound-bound absorption in the isolated ion is detected by the observation of Ni 2 + → Ni + + Ni sequential two-photon dissociation. Progressions of vibronic bands with partially resolved rotational structure belonging to several distinct electronic transitions in Ni 2 + have been observed in the interval between 16250 and 23500 cm −1. The appearance and preliminary analysis of this resonant two-photon dissociation (R2PD) spectrum will be discussed.

ChemInform Abstract: ELECTRONIC SPECTRA OF BUTADIENE AND ITS METHYL DERIVATIVES: A MULTIPHOTON IONIZATION STUDY

The multiphoton ionization (MPI) spectra of trans‐1,3‐butadiene and three of its methyl substituted derivatives have been recorded using a tunable visible dye laser. The effect of methyl substitution on the electronic structure of butadiene is investigated, resulting in a reassignment of the spectra of these molecules. Quantum defects are found to be independent of principal quantum number, indicating little mixing between Rydberg and core orbitals. The validity of retaining conventional s, p, d, and f descriptions of Rydberg orbitals in these quasilinear molecules is demonstrated. Two electronic states of butadiene, assigned to the 3d and 4s Rydberg states, are observed for the first time in optical spectroscopy. No evidence for an excited 1Ag valence state is found in the MPI spectra.

Electronic spectra of butadiene and its methyl derivatives: A multiphoton ionization study

The multiphoton ionization (MPI) spectra of trans-1,3-butadiene and three of its methyl substituted derivatives have been recorded using a tunable visible dye laser. The effect of methyl substitution on the electronic structure of butadiene is investigated, resulting in a reassignment of the spectra of these molecules. Quantum defects are found to be independent of principal quantum number, indicating little mixing between Rydberg and core orbitals. The validity of retaining conventional s, p, d, and f descriptions of Rydberg orbitals in these quasilinear molecules is demonstrated. Two electronic states of butadiene, assigned to the 3d and 4s Rydberg states, are observed for the first time in optical spectroscopy. No evidence for an excited 1Ag valence state is found in the MPI spectra.

Multiphoton ionization of metal atoms produced in the photodissociation of group VI hexacarbonyls

The photodissociation of M(CO) 6, M = Cr or W, and the multiphoton ionization spectra of the resulting atoms M(I) have been studied using a tunable visible dye laser M(I) fragments are produced throughout the range between 363 and 585 nm, and multiphoton absorption allows all of the states formed to be probed.

Tunable lasers and applications (Proc. Loen Conf., Norway, 1976)

A review is given of the Proceedings of the International Conference on Tunable Lasers and Applications which took place in Loen, Norway June 6?11, 1976 and were published by Springer Verlag, Berlin in 1976. The main results are reviewed under the following headings: I) tunable high-energy ultraviolet and visible lasers; II) tunable infrared lasers; III) isotope separation and laser chemistry; IV) nonlinear excitation of molecules by high-intensity infrared laser radiation; V) laser photokinetics; VI) atmospheric photochemistry and diagnostics; VII) photobiology; VIII) spectroscopic applications of tunable lasers. The following tendencies are identified in the design and application of tunable lasers: 1) development and studies of high-power tunable infrared lasers; 2) development of tunable ultraviolet excimer lasers; 3) intensification of studies of laser isotope separation by selective dissociation of molecules in a strong infrared field; 4) extensive work in laser spectroscopy; 5) application of laser methods to studies of biological objects.

Tuning into infrared

Tunable infrared lasers have proved more difficult to develop than tunable visible lasers such as dye lasers. Although various approaches have been successful in generating tunable infrared, they have involved considerable complexity and expense. Recent work however in the Electronics Department at Southampton University has shown that stimulated Raman scattering in alkali metal vapours can offer a simple method for converting the beam from a tunable dye laser into an intense, coherent beam of tunable infrared radiation.

Opto-acoustic spectroscopy with a visible CW dye laser

The first use of a tunable visible laser in conjunction with an opto-acoustic cell is described. By using a longitudinal resonance of the gas cell NO 2 can be detected around 10 p.p.b., the same order of detectivity as in the infrared. The use of the technique for studying photodissociation in the visible and u.v. is discussed.