Generally, NDT reflects the quality of regenerative signal: this website higher NDT, higher quality. Regardless of the absorption

A, higher NDT demands lower saturation fluence F S . From the adjustments of this NDT analytic expression represented in dotted lines in Figure 1 with experimental curves, we extract F S values of 9, 70, and 726 μJ cm-2 for M-SWCNT, MQW, and B-SWCNT, respectively. These results indicate that M-SWCNT-based photonics devices are expected to consume eight times less than MQW-based and 80 times less than B-SWCNT-based devices. The greater B-SWCNT F S value, in comparison with M-SWCNT, is associated with the higher number of nonradiative excitonic relaxation pathways in B-SWCNTs, especially due to charge tunnel transfer from semiconducting to metallic tubes selleck kinase inhibitor within a bundle [6]. Hence, shorter exciton lifetime in B-SWCNT than in M-SWCNT leads to greater incident energy to saturate B-SWCNT absorption

than M-SWCNT absorption. Figure 1 NDT for M-SWCNT, B-SWCNT, and MQW as a function of incident pump fluence at 1550-nm excitation wavelength. Finally, M-SWCNT are promising nonlinear materials for efficient, ultrafast, low-cost future passive photonics devices in optical networking with lower power consumption than conventional MQW semiconductors. A further progress to lower power consumption again should be loaded by the alignment of SWCNT in order to favor light-matter

interactions. This technological step is in progress. Toward active photonics devices: SWCNT photoluminescence experiments Among the key requirements for light sources in optical networking, emission stabilities with temperature and incident power are of great importance. Also, light emission from SWCNT requires debundling of SWCNT [12], as huge numbers of excitonic nonradiative recombination pathways are available within bundles, selleck compound thanks to tube-tube contacts, leading to photoluminescence (PL) quenching. Therefore, only M-SWCNT sample studies are suitable for active photonics applications. The preparation of M-SWCNT samples is mentioned above. Light emission of M-SWCNT is characterized by PL spectroscopy experiments, using continuous-wave RANTES excitation laser and InGaAs detector, covering 800- to 1,700-nm wavelength window. Figure 2 shows M-SWCNT photoluminescence spectra at room temperature and 659-nm excitation wavelength, under different incident power levels (from 0.7 to 20.0 mW). We observe different light-emission peaks, which are attributed to different SWCNT chiralities. The particular behavior of light-emission M-SWCNT highlighted by these PL spectra is that no obvious emission wavelength shift is observed, whereas incident excitation power changes. Furthermore, PL intensities exhibit a linear dependence (see the inset of Figure 2) on incident power, over the excitation range examined.