Incident Power Dependence

At lower power values, there is relatively less spectral broadening, and it appears to be mostly symmetrical around the incident wavelength of 801 nm, 

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The demonstration of linear incident power dependence for upconversion process using both coherent and noncoherent light sources ... 

Another physical phenomenon connected also with the change of occupation number of ground state and consequently with an incident power dependent refraction index variation (cf. Heeger et al. (I986)) is photoinduced absorption observed in polyacetylenes (Orenstein and Baker (1982)), polydiacetylenes (Orenstein et al. (198 )) and polythiophenes (Moraes et al. (198 )). In this process (cf. Fig. 20) with the pump at (o energy corresponding to the first allowed one photon transition one varies refractive index in both visible (o) ) and infrared frequencies. 

The incident power dependence of frequency tripling efficiency is shown in Fig. 27. Actually due to the free harmonic wave absorption this efficiency will be slighly smaller. The large light intensity is realized by focusing a 40 nj laser pulse with 10 fs duration pulse on a surface of 100(pm). ... 

FIGURE 6.7 Squares the calculated amplitude of the electric field of the TH wave generated by a particle of diameter, D. is the wavelength of the incident radiation in the particle s material. Solid line with the sixth power dependence of the TH signal on the particles diameter. Solid line the fourth power dependence of the TH signal on the particles diameter. 

FIGURE 6.8 TH power generated from a 200-nm-diameter polystyrene particle trapped by a CW laser beam as a fnnction of the incident power of the trapping beam. Dashed line shows a third-power dependence on the incident power. 

For a high density optical recording medium, two important parameters which characterize its capability are the size of mark and the threshold energy density required for mark creation. The size of the mark was found to be dependent on both the incident power and the exposure time. The size of the marked areas is shown in Figure 6 for different levels of power and exposure... 

To account for the alternate ranges of effective incident power densities, the internal field E need only have a small nonlinear dependence upon the external field (E ) at specific values of internal electric field (E) that yield enhanced efflux. At all other values of E, the dependence of E av on Eq may be entirely linear. A plot of IElav versus Eq... 

Human subjects, whose heads were irradiated with rectangular pulse modulated microwave energy with peak incident power density on the order of 300 mW/cm, perceived an audible sound. The frequencies of these microwaves ranged from 200 to 3000 MHz, while the pulsewidths varied from 1 to 150 js (1,6,9,10,11). The sensation appeared as a barely audible click, buzz or chirp depending on such factors as pulsewidth and repetition frequency of the incident radiation, and usually was perceived as originating from within or near the head. When earplugs were used to attenuate ambient noise, the subject would indicate an apparent increase in the level of microwave-induced sound. The sensation occurred instantaneously and was independent of the subject s orientation in the microwave field. 

Fig. 37. Potential dependences of current in dark and under illumination for polycrystalline diamond electrode in 0.1 M KH2PO4 solution. Light quantum energy (a) 6.4 eV (b) 5 eV. Incident power density 80 mW cm 2 [163]. Reproduced by permission of The Electrochemical Society, Inc.

Figure 2.8 Energy stored per unit volume is dependent upon incident power flow and...

The figure of merit for a millimeter diode operated as a detector is the video resistance Ry, which in turn depends on Rg, which has a significant power dependence for high incident powers through its dependence on 1. The current responsivity /3 is only weakly dependent on the incident power, and we will take it be 1 /i,A//xW for this analysis. For an incident power of 1 mW, Eq. (74) implies /5 = 1 mA, and we may use Eq. (76) to show Rg = 25 fl. For an incident power of a few microwatts or lower, Eq. (76) shows that Rg is essentially independent of input power and equal to 5000 fi. Hence, high incident powers reduce the video resistance. 

A complication to the frequency dependency of aj arose when photon counting detectors were introduced into Raman instrumentation. Virtually all modern spectrometers count photons rather than measure watts, and the two differ by a factor of hv. Since the incident and scattered photons differ in energy, the ratio of scattered to incident power differs from the ratio of scattered to incident photon flux. The consequences of this difference are quantitatively fairly minor, but conceptually important. Derivations based on photons/second and photon counting are more consistent with a quantum mechanical treatment where a cross section is effectively a statement of probability, whereas the classical treatment is based on induced dipoles. If Eq. (2.9) is rewritten for photon counting systems, Eq. (2.11) results ... 

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