Effects of different Raman pumping schemes on stimulated Brillouin scattering in a linear cavity

The effects of backward, forward, and bidirectional Raman pumping schemes on stimulated Brillouin scattering (SBS) is investigated in this study. By using a linear cavity, we utilize residual Brillouin pump (BP) and Raman pump (RP) power after each transmission through a 25 km single-mode fiber (SMF) used as a gain medium. The SBS threshold power is reduced in the forward, backward, and bidirectional Raman pumping schemes by 2.5, 1.75, and 2.75dB, respectively when the 1480nm RP power is fixed at 150mW and the BP wavelength is 1580 nm. Surprisingly, it is revealed that the SBS threshold reduction depends strongly and solely on Raman gain and it is independent of the Raman pumping schemes. In addition, the effect of Raman amplification on SBS is more effective at the SBS threshold, especially in the bidirectional and forward schemes

Biological control of Phytophthora drechsleri Tucker, the causal agent of pistachio gummosis, under greenhouse conditions by use of Actinomycetes

Actinomycetes enhance soil fertility and have antagonistic activity against wide range of plant root-pathogens. These microorganisms were isolated from agricultural soils of Kerman as pure cultures. Phytophthora drechsleri Tucker, causes gummosis and root rot of pistachio trees worldwide. From 130 Actinomycetes isolates, 12 inhibited growth of the pathogen of pistachio gummosis in culture plates and four of the most active isolates exhibited biological control of the pathogen under greenhouse conditions. When plants were grown in sterile soil mix and treated both with Actinomycetes and the pathogen, the number of healthy plants increased dramatically and the symptoms on diseased plants were less severe in comparison with seedlings treated with the pathogen alone. From the collected data it was well conclusive that in greenhouse tests, soil applications of Actinomycetes controlled causal agent of root rot of pistachio seedlings. Antifungal activity was of fungicidal type on the pathogen mycelia. From the stand point of biotechnological goals, the results indicate that the active isolates can be investigated for use as biofertilizers, biofungicides and use in future development of recombinant DNA in pistachio trees bearing elevated resistance to gummosis. Field trials of the active isolates are under investigatio

Multiple wavelength generation using a compacted hybrid Raman / Bi-EDF amplifier

A multiple wavelength laser source is generated by a Brillouin seed signal and a compacted hybrid Raman / bismuth-based erbium doped fiber amplifier (Bi-EDFA) in a linear cavity. The gain media of the Raman/Bi-EDFA is only a 2.15 m Bi-EDF pumped bi-directionally by two laser diodes (LDs). In comparison to all of the conventional multiple wavelength sources generated via using the same Bi-EDF and LDs, the proposed multiple wavelength source has much more number of lines due to using Raman and EDF amplification