Laser bandwidth

Experimentally, dvz is directly proportional to the laser bandwidth and is a constant dvx is determined by the slit width and is inversely proportional to the ion arrival time (i.e. a ID solid angle factor) and dvy/dt denotes the time-to-speed transformation in the ion TOF measurement, which can readily be derived from the equation of motion. It was found... 

In praetiee, one nses femtosecond lasers, which necessarily feature a broader spectrum the shorter the pulses are. This provides another benefit for multiphoton imaging ultrashort pulses (sub-20 femtoseconds [fs]) possess a laser bandwidth increased in such a way that several typical flurophores with different emission wavelengths can be excited at once. Usually, fluorescence signals in microscopy are recorded in a single... 

Influence of Laser Bandwidth and Effective Pulse Duration on Nonlinear Signal Intensity, Showing the Dramatic Effect of Dispersion on Ultrashort Pulses... 

Another technological breakthrough in optical hber technology, however, allows one to upgrade established 100 fs-class laser systems for broadband applications and even surpass the bandwidth of dedicated short-pulse Ti sapphire lasers. Key to this is the use of novel microstructured optical hbers, which are designed to exhibit extremely high optical nonlinearities. If nanojoule femtosecond laser pulses are launched into such a hber, the combination of different nonlinear optical processes leads to the creation of new frequency components. Therefore, the laser bandwidth can be increased dramatically by orders of magnitude. 

The laser atomic fluorescence excitation and emission spectra of sodium in an air-acetylene flame are shown below. In the excitation spectrum, the laser (bandwidth = 0.03 nm) was scanned through various wavelengths while the detector monochromator (bandwidth = 1.6 nm) was held fixed near 589 nm. In the emission spectrum, the laser was fixed at 589.0 nm, and the detector monochromator wavelength was varied. Explain why the emission spectrum gives one broad band, whereas the excitation spectrum gives two sharp lines. How can the excitation linewidths be much narrower than the detector monochromator bandwidth ... 

The instrument variables Rs, RB, and Rs + 2RB are used in instrument optimization for example, an improved matching of the laser bandwidth to the HO absorption could increase Rs, a reduction in illumination of walls near the detection zone by ambient light or scattered or diffracted laser light could decrease RB, and an increase in photon collection efficiency could increase (Rs + 2RB). The remaining quantities fav, MAT, SNR, and MDC may be traded off during data processing, but the choice of their values is restricted by the instrument variables. 

From a frequency domain point of view, a femtosecond pump-probe experiment, shown schematically in Fig. 1, is a sum of coherent two-photon transition amplitudes constrained by the pump and probe laser bandwidths. The measured signal is proportional to the population in the final state Tf) at the end of the two-pulse sequence. As these two-photon transitions are coherent, we must therefore add the transition amplitudes and then square in order to obtain the probability. As discussed below, the signal contains interferences between all degenerate two-photon transitions. When the time delay between the two laser fields is varied, the... 

During the course of laser resonance experiments it was noticed that the central wavelengths shift depending on the helium density. Thus, the resonance line shapes at various target gas conditions were measured precisely with a reduced laser bandwidth and an improved wavelength calibration [18]. Figure 5 shows resonance profiles taken for the 597.26 nm line at different pressures ranging from 530 mb to 8.0 bar at temperatures of 5.8-6.3 K. The results are summarized in Table 2. 

Fig. 11. (Upper) Splitting of pHe+ states due to magnetic interactions, and observable laser transitions between the F+ and F states according to Bakalov and Korobov [33]. (Lower) Observed hyperfine splitting of the unfavoured laser transition (n, L) = (38,34) —> (37, 35) [16]. The laser bandwidth is 1.2 GHz. The solid line is the result of a fit of two Voigt functions (a Gaussian fixed to the laser bandwidth convoluted with a Lorentzian to describe the intrinsic line width) to the spectrum. The intrinsic width of each lines was found to 0.4 0.1 GHz. From Widmann et al. [16]...

To calculate the vibrational echo observable for a fixed laser frequency, >i, P(3) must be integrated over the spectroscopic line, g(to), or the laser bandwidth, whichever is narrower, and then the modulus square of the result must be integrated over all time since the observable is the integrated intensity of the vibrational echo pulse,... 

Twenty configurations from a 35 ps ground state adiabatic trajectory, chosen to be on resonance with the laser bandwidth corresponding to the experiments, were selected as the starting points for non-adiabatic excited state trajectories. A corresponding set of trajectories was run in D2O, with a model identical in all respects to the work described previously except that the mass of the H atom was changed from 1 to 2 amu, and preliminary results of the behavior in D2O are included here. 

Finally, the actual laser bandwidth was varied by using a combination of intracavity filters and etalons. In all these experiments the vibrational and rotational temperatures were typically <20-40 K and <10 K, respectively, depending on the molecular-beam conditions. 

We have attempted to simulate the observed fluorescence spectrum using the determined vibrational populations and various rotational distributions. A calculated spectrum is convoluted with the measured laser bandwidth profile and compared with the experimental scans to determine the best rotational distribution. We... 

Figure 36. General level schematic pertaining to IVR and portraying the possibility of mixing between optically active states outside the laser bandwidth (A

Figure 41. Measured fluorescence decays of the 1750 cm-1 (h-type) band in the v,b = 1420cm"1 spectrum of jet-cooled anthracene as a function of carrier gas parameters. Decays were measured under identical conditions except for carrier gas. For each decay x = 6 mm, the monochromator resolution R = 3.2 A, and the laser bandwidth BW cs 2 cm"1.

---