Center launching condition

We developed a GI POF with an acrylic-polymer-based heterogeneous core, whose attenuation was 200 dB/km at 670 nm. The attenuation produces a radiation loss of around 50 dB/km because of the intrinsic scattering due to microscopic core heterogeneities. The core diameter and NA were 200 pm and 0.3, respectively. Figure 3.17 shows microscopic images of the input beams on the fiber near-end faces and the output beams on the PD for the GI POF under the center launching condition. As shown in Figure 3.17b, the output beam pattern of the GI POF... 

Figure 3.18 Noise floor spectra of optical links with 2-m Gi POF and 2-m giass MMFs under center launching condition. Near-end faces of all the fibers are polished flat.

Figure 3.20 Microscopic images of back-reflected beam patterns from (a) glass MMF with obliquely polished far-end face, (b) glass MMF with flat-polished far-end face, and (c) Gl POF with flat-polished far-end face under center launching conditions.

Figure 3.21 shows the reflected beam patterns from the fibers under an off-axis launching condition with an offset of 25 pm. For the Gl POF, the reflected beam has a speckled pattern similar to that for the center launching condition (Figure 3.20c), whereas the reflected pattern reflects the initially launched mode... 

Figure 6.5 Schematic diagrams of (a) underfilled launching condition where oniy iower-order modes propagating near the core center are selectiveiy excited, (b) Overfiiied iaunch-ing condition where all the modes are uniformly excited.

Because the initial vibrational state for absorption spectra often is v = 0, the vibrational nonstationary state typically produced initially is an only slightly distorted Gaussian wavepacket centered at R"g. Conservation of momentum requires that this approximately minimum-uncertainty wavepacket be launched at the turning point on the upper surface, R e = R"g, which lies vertically above R"g. [This is a consequence of the stationary phase condition, see Sections 5.1.1 and 7.6 and Tellinghuisen s (1984) discussion of the classical Franck-Condon... 

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