Linewidths reduction

Optical feedback can be used to achieve dramatic linewidth reduction. By placing a SL in an external cavity, the linewidth may be reduced by as much as the square of the increase in the photon lifetime (i.e., several orders of magnitude). The linewidth of the external cavity SL, related to that of a solitary device at the same pump level,, by the... 

S. Saito, 0. Nilsson and Y. Yamamoto, Frequency modulation noise and linewidth reduction in a semiconductor laser by means of negative frequency feedback technique, Appl. Phys. Lett. 46 3 (1985). 

Although electroless deposition seems to offer greater prospects for deposit thickness and composition uniformity than electrodeposition, the achievement of such uniformity is a challenge. An understanding of catalysis and deposition mechanisms, as in Section 3, is inadequate to describe the operation of a practical electroless solution. Solution factors, such as the presence of stabilizers, dissolved O2 gas, and partially-diffusion-controlled, metal ion reduction reactions, often can strongly influence deposit uniformity. In the field of microelectronics, backend-of-line (BEOL) linewidths are approaching 0.1 pm, which is much less than the diffusion layer thickness for a... 

Prior knowledge allows to include fixed relations between some of the four parameters (amplitude, phase, frequency position, peak width) describing a symmetrical well-shaped resonance. Signal ratios, chemical shift difierences, linewidth relations and zero-order phase relations can be included. The reduction of the number of unknown parameters leads to a reduced calculation time, better convergence behaviour and improved results. However, the assumptions made to include the prior knowledge must be validated for each experiment. Differences between the parameter values set by the prior knowledge and the actual parameters could lead to systematic errors. 

The single-mode laser naturally gives less output power than a multimode laser with the same active volume since its induced emission is concentrated into a smaller frequency range. This loss in intensity, however, is much less than one would expect from the ratio of linewidths or from the reduction in oscillating mode number 3i. 32,41) jbis is due to the fact, that not only atoms with the exact transition frequency can contribute to the induced emission, but also those inside the homogeneous linewidth which is determined by collision processes in the case of gas lasers or by crystal line broadening in solid lasers... 

FIGURE 5. Reduction in linewidth in the Li solid state NMR spectrum of the dimer of ( )-2-lithio-l-phenyl-1-(o-hthiophenyl)pent-l-ene (90% Li) by various techniques (a) static Li H spectmm, halfwidth 6.3 kHz (b) Li H CP/MAS spectmm, rotational frequency 3 kHz (c) central transition in the Li H CP/MAS spectmm, halfwidth 130 Hz (d) central transition in the Li H CP/MAS spectmm with additional Li decouphng. The two Li resonances are separated by 1.25 ppm hneshape analysis yields half-widths of 92 and 81 Hz, respectively ... 

The first and most obvious question is whether or not a narrower velocity distribution leads to narrower collisional resonances. In Fig. 14.14 we show the Na 26s + Na 26s — Na 26p + Na 25p resonances obtained under three different experimental conditions.20 In Fig. 14.14(a) the atoms are in a thermal 670 K beam. In Figs. 14.14(b) and (c) the beam is velocity selected using the approach shown in Fig. 14.13 to collision velocities of 7.5 X 103 and 3.8 X 103 cm/s, respectively. The dramatic reduction in the linewidths of the collisional resonances is evident. The calculated linewidths are 400, 28, and 10 MHz, and the widths of the collisional resonances shown in Figs. 14.14(a)-(c) are 350,40, and 23 MHz respectively. The widths decrease approximately as l/v3/2 until Fig. 14.14(c), at which point the inhomogeneities of the electric field mask the intrinsic linewidth of the collisional resonance. 

In all our linewidth studies the width of the central peak was measured—i.e., the linewidth obeying Equation lib. In Ref. 45 we reported 23Na linewidth studies on a lamellar mesophase containing egg-yolk lecithin. The effect of cholesterol on the linewidth was investigated, and we found that with increasing cholesterol content in the phospholipid bilayers a marked reduction in the linewidth was observed. In accordance with similar investigations for simple soap-alcohol-water lamellar mesophases (42, 43) this is interpreted as a partial release of... 

The reduction of exchange interactions from Cu(en) to Co(phen) compound in investigated series is evident from results of Table 2. The temperature dependence of the linewidth correlates well with this sequence. 

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