Related papers: Threshold non-linear absorption in Zeeman transiti…
The guided modes of sub-wavelength diameter air-clad optical fibers exhibit a pronounced evanescent field. The absorption of particles on the fiber surface is therefore readily detected via the fiber transmission. We show that the resulting…
The APM multicolor survey for bright z > 4 objects, covering 2500 deg^2 of sky to m(R)~19, resulted in the discovery of thirty-one quasars with z > 4. High signal-to-noise optical spectrophotometry at 5A resolution has been obtained for the…
Understanding the cosmic re-ionization is one of the key goals of the modern observational cosmology. High redshift QSO spectra can be used as background light sources to measure absorption by intervening neutral hydrogen. We investigate…
Using an Electrically Focus Tunable Lens (EFTL), an integrating sphere and a tunable femtosecond-pulse laser (Mai Tai HP), we were able to measure the degenerate two-photon absorption coefficient (in transmission) of CdS and ZnSe in a long…
Transient absorption is a very powerful observable in attosecond experiments on atoms, molecules and solids and is frequently used in experiments employing phase-locked few-cycle infrared and XUV laser pulses derived from high harmonic…
This paper discusses the first observation of stimulated magnetic resonance transitions between the hyperfine levels of trapped ground state atomic antihydrogen, confirming its presence in the ALPHA apparatus. Our observations show that…
Nonlinear photoemission from a silver single crystal is investigated by femtosecond laser pulses in a perturbative regime. A clear observation of above-threshold photoemission in solids is reported for the first time. The ratio between the…
We report on the improved measurement of the hyperfine structure of $4f^{12}(^3 H_6)5d_{5/2}6s^2$ $(J=9/2)$ excited state in Tm-169 which is involved in the second-stage laser cooling of Tm. To measure the absolute value of the hyperfine…
We demonstrate a technique for directly measuring the quadratic Zeeman shift using stimulated Raman transitions.The quadratic Zeeman shift has been measured yielding [delta][nju] = 1296.8 +/-3.3 Hz/G^{2} for magnetically insensitive…
Weak transitions in the (2,0) overtone band of the HD molecule at $\lambda = 1.38 \, \mu$m were measured in saturated absorption using the technique of noise-immune cavity-enhanced optical heterodyne molecular spectroscopy. Narrow…
Optical transitions of highly charged ions can be very sensitive to hypothetical beyond-the-Standard-Model phenomena. Those near the $5s-4f$ level crossing, where the $5s$ and $4f$ are degenerate are especially promising. We present…
We present a detailed study of the absolute Doppler-broadened absorption of a probe beam scanned across the potassium D lines in a thermal vapour. Spectra using a weak probe were measured on the 4S $\rightarrow$ 4P transition and compared…
We report new HST and ground-based observations of a damped Lyman-alpha absorption system toward the QSO 0850+4400. The redshift of the absorption system is z = 0.163770 and the neutral hydrogen column density of the absorption system is…
It is demonstrated that velocity selective optical pumping/saturation resonances of reduced absorption in a Rb vapor nanocell with thickness \textit{L=} $\lambda $, 2$\lambda $, and 3$\lambda $ (resonant wavelength $\lambda $ = 780 nm)…
A femtosecond mode-locked laser is used for the first time as a broadband infrared source for high resolution Fourier transform absorption spectroscopy. Demontration is made with a Cr^4+:YAG laser. The entire nu_1+nu_3 vibration-rotation…
A simple theoretical model describing the positive sign of subnatural-width absorption resonances in the recent experiment of Akulshin and co-workers (Phys. Rev. A, {\bf 57}, 2996 (1998)) is proposed. An analytical expression for the linear…
Ultrafast degenerate pump-probe experiments performed on a free standing film of double walled carbon nanotubes near the first metallic transition energy of outer tube show ultrafast ($97 fs$) photobleaching followed by a photo-induced…
Nonlinear frequency conversion provides an elegant method to detect photons in a spectral range which differs from the pump wavelength, making it highly attractive for photons with inherently low energy. Aside from the intensity of the…
When a noble gas atom approaches a solid surface, it is adsorbed via the Van der Waals force, which is called physisorption. In this thesis, several experimental results concerning physisorbed atoms at surfaces are presented. First, photon…
This study introduces a graphene-assisted terahertz metamaterial absorber operating at a resonance frequency of 8.436 THz. The unit cell incorporates a graphene-based split-ring resonator (SRR) configuration with additional auxiliary splits…