A simple linear cavity erbium-doped fiber laser based on a Fabry-Perot filter which consists of a pair of fiber Bragg gratings is proposed for tunable and switchable single-longitudinal-mode dualwavelength operation. The single-longitudinal-mode is obtained by the saturable absorption of an unpumed erbium-doped fiber together with a narrow-band fiber Bragg grating. Under the high pump power (>166mW) condition, the stable dual-wavelength oscillation with uniform amplitude can be realized by carefully adjusting the polarization controller in the cavity. Wavelength selection and switching are achieved by tuning the narrow-band fiber Bragg grating in the system. The spacing of the dualwavelength can be selected at 0.20nm (~ 25.62GHz), 0.22nm (~ 28.19GHz) and 0.54nm (~ 69.19GHz). ©2009 Optical Society of AmericaOCIS codes: (000.0000) General; (000.2700) General science. References and links1. N. J. C. Libatique, and R. K. Jain, "Precisely and rapidly wavelength-switchable narrow-linewidth 1.5µm laser source for wavelength division multiplexing applications," IEEE Photon. Technol. Lett. 11(12), 1584-1586 (1999). 2. Z. Chen, S. Ma, and N. K. Dutta, "Stable dual wavelength mode-locked Erbium-doped fiber ring laser," in Frontiers in Optics, OSA Technical Digest, paper

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Unlike common metals, graphene can support transverse electric (TE) surface modes when the imaginary part of its conductivity is negative. We have theoretically investigated and numerically simulated plasmonic properties of graphene TE surface plasmons (SPs) in the terahertz regime. The influence of the external magnetic field, gate voltage and temperature as the tuning schemes of the SPs have been investigated. The results show that graphene TE modes can be realized by tuning the magnetic fields or gate voltage. If the permeability of the dielectrics on both sides of the graphene layer differs enough, the graphene TE modes can still be achieved. The work presented here has the potential for application to graphene-based plasmonic devices in photonics and optoelectronics, such as sensors, polarizers and modulators.

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