In recent years, semiconductor nanocrystals quantum dots (QDs) have been extensively studied because of their unique optical and electronic properties compared to their bulk counterparts. This ability to tune the bandgap of the QDs through the control of the particle size can provide near-infrared emission covering the important wavelength region for the fiber optic communication. We have doped the optical fiber core by quantum dots (QDs) to integrate the emission characteristics of quantum dots with propagation characteristics of optical fiber. In particular, narrow bandgap materials such as PbS and PbSe have attracted much attention. Due to the large bulk exciton Bohr radii of PbS (18 nm), quantum confinement effect can be achieved over the wide range of the particle size. Application specific QDs can be incorporated into the optical fiber core. It was reported that PbS nanoparticles could provide the emission over the whole transmission window (1200–1700 nm) of silica fibers, and therefore could be promising for all-wave optical amplifiers. We have carried out numerical investigation such amplifier characteristics and have shown incremental gain values. Simulation results show that it is possible to design an optical amplifier with flattened gain characteristics over S, C, and L bands with low noise figure, moderate optical signal to noise ratio and minimum gain of 10 dB.

Quantum dots; excitons; nanoparticles; quantum confinement; amplified stimulated emission

[1] W. Huang, Y.-Z. Chi, X. Wang, S.-F. Zhou, L. Wang, E. Wu, H.-P. Zeng, and J. R. Qiu, “Tunable infrared luminescence and optical amplification in PbS-doped glasses,” Chin. Phys. Lett., vol. 25, pp. 2518–2520, 2008.
[2] H. Jong and L.Chao, “Pbs quantum-dots in glassmatrix for universal fiber optic amplifier”, J. Mater. Sci: Mater. Electron., vol. 18, pp. S135–S139, 2007.
[3] G. P. Agrawal, “Fiber-Optic Communication Systems,” 3 ed. John Wiley & Sons, Inc., New York, 2002.
[4] http://en.wikipedia.org/wiki/Quantum_dot
[5] D. Bimberg, M. Grundmann, and N. N. Ledentsov, “Quantum dot heterostructures,” John Wiley, Chichester, 1999.
[6] S. M. Reimann and M. Manninen, “Electronic structure of quantum dots”, Rev. Mod. Phys., vol. 74, pp. 1283-1342, 2002.
[7] X. Michalet, F. F. Pinaud, L. A. Bentolila, J. M. Tsay, S. Doose, J. J. Li, G. Sundaresan, A. M. Wu, S. S. Gambhir, and S. Weiss, “Quantum dots for live cells, in vivo imaging and diagnostics,” Science, vol. 307, pp. 538-544 (2005).
[8] Y. Masumoto and T. Takagahara, “Semiconductor Quantum Dots,” Springer Verlag, Berlin, Heidelberg, New York, 2002.
[9] A. E. Zhukov, A. R. Kovsh, N. A. Maleev, S. S. Mikhrin, V. M. Ustinov, A. F. Tsatsul'nikov, M. V. Maximov, B. V. Volovik, D. A. Bedarev, Yu. M. Shernyakov, P. S. Kop'ev, Zh. I. Alferov, N. N. Ledentsov, and D. Bimberg, “Long wavelength lasing from multiply stacked InAs/InGaAs quantum dots on GaAs substrates,” Appl. Phys. Lett., vol. 75, pp. 1926-1934, 1999.
[10] C. R. Giles and D. Emmanuel, “Modeling erbium-doped fiber amplifiers,” J. Lightw. Technol., vol. 9, no. 2, pp. 271–283, 1991.
[11] T. Wang, F. Pang, K. Wang, R. Zhang and G. Liu, “Evanescent wave coupled semiconductor quantum dots fiber amplifier based on reverse Micelle method,” Proceedings of the 7th IEEE, International Conference on Nanotechnology, Hong Kong, pp. 819–822, Aug. 2–5, 2007.
[12] Y. Wang, A. Suna, W. Mahler, R. Kasowski, “PbS in polymers. From molecules to bulk solids,” J. Chem. Phys., vol. 87, pp. 7315-7322, 1987.
[13] L. E. Brus, “Electron-Electron and Electron-Hole Interaction in Small Semiconductor Crystallites: The Size Dependence of The Lowest Excited Electronic State,” J. Chem. Phys., vol. 80, pp. 4403-4418, 1984.
[14] M. V. R. Krishna, and R. A. Friesner, “Quantum Confinement Effects inSemiconductor Clusters,” J. Chem. Phys., vol. 95, pp. 8309-8321, 1991.
[15] F. W. Wise, “Lead salt quantum dots: The limit of strong quantum confinement,” Acc. Chem. Res., vol. 33, no. 11, pp. 773–780, 2000.
[16] K. Nakagawa, S. Nishi, K. Aida, and E. Y oneda, "Trunk and distribution network application of Erbium-doped fiber amplifier," J. Lightwave Technol.,vol.9, pp. 198-221, 1991.
[17] C. Jiang, “Ultrabroadband Gain Characteristics of a Quantum-Dot-Doped Fiber Amplifier,” IEEE J. Sel. Top. Quantum Electron., Vol. 15(1), pp. 140–144, 2009.
[18] L. Chao, H. Jong, Z. Xianghua, and A. Jean-Luc, “Photoluminescence of PbS quantum dots embedded in glasses,” J. Non-Cryst. Solids, vol. 354, pp. 618–623, 2008.
[19] F. C. BECKER, N. A. OLSSON, J. R. SIMPSON, “Erbium-Doped Fiber Amplifiers Fundamentals and Technology,” Optics and Photonics, New York, 1997.
[20] C. R. Giles and D. Emmanuel, “Modeling erbium-doped fiber amplifiers,” J. Lightw. Technol., vol. 9, no. 2, pp. 271–283, 1991.
[21] K. Thyagarajan, Jagneet Kaur, “A novel design of an intrinsically gain flattened erbium doped fiber,” Optics Communications, vol. 183. pp. 407–413, 2000.
[22] Cheng Cheng, “A Multiquantum-Dot-Doped Fiber Amplifier with Characteristics of Broadband, Flat Gain, and Low Noise,” J. of Lightw . Technol., vol. 26, no. 11, pp. 1404-1410, 2008.