The Brillouin gain properties in a double-clad As2Se3 photonic crystal fiber（PCF）are simulated based on the finite-element method（FEM）.The results indicate that the Brillouin gain spectrum（BGS）of our proposed ch...The Brillouin gain properties in a double-clad As2Se3 photonic crystal fiber（PCF）are simulated based on the finite-element method（FEM）.The results indicate that the Brillouin gain spectrum（BGS）of our proposed chalcogenide PCF exhibits a multipeaked behavior and has a high Brillouin gain coefficient.We also find that a larger size of inner cladding air holes will lead to a more pronounced second peak in the BGS.On the other hand,the size of the outer cladding has nearly no effect on the BGS behavior.Through these results,one can tailor the Stimulated Brillouin scattering effect in PCFs for a wide range of applications.展开更多
Typically, photonic waveguides designed for nonlinear frequency conversion rely on intuitive and established principles, including index guiding and bandgap engineering, and are based on simple shapes with high degree...Typically, photonic waveguides designed for nonlinear frequency conversion rely on intuitive and established principles, including index guiding and bandgap engineering, and are based on simple shapes with high degrees of symmetry. We show that recently developed inverse-design techniques can be applied to discover new kinds of microstructured fibers and metasurfaces designed to achieve large nonlinear frequency-conversion efficiencies. As a proof of principle, we demonstrate complex, wavelength-scale chalcogenide glass fibers and gallium phosphide three-dimensional metasurfaces exhibiting some of the largest nonlinear conversion efficiencies predicted thus far,e.g., lowering the power requirement for third-harmonic generation by 104 and enhancing second-harmonic generation conversion efficiency by 107. Such enhancements arise because, in addition to enabling a great degree of tunability in the choice of design wavelengths, these optimization tools ensure both frequency-and phase-matching in addition to large nonlinear overlap factors.展开更多
A novel asymmetrical twin-core photonic crystal fiber was proposed, whose effective overlap core area Aeff can be designed to synchronize the variation of Raman gain coefficient with respect to frequency. This fiber p...A novel asymmetrical twin-core photonic crystal fiber was proposed, whose effective overlap core area Aeff can be designed to synchronize the variation of Raman gain coefficient with respect to frequency. This fiber possesses a higher and flatter Raman gain efficiency coefficient curve rR=gR/Aeff over a specified band of wavelength than a conventional fiber. Therefore, it is a good candidate of gain me- dium for a flat, broad gain band fiber Raman amplifier. It was numerically demonstrated that for the Raman gain efficiency rR, relative fluctuations of less than 2.2% and 5.7% are achievable in the C (1530―1565 nm) band and L (1565―1625 nm) band, respectively.展开更多
基金supported by the International Cooperation Projects between China and Singapore under Grant No.2009DFA12640
文摘The Brillouin gain properties in a double-clad As2Se3 photonic crystal fiber（PCF）are simulated based on the finite-element method（FEM）.The results indicate that the Brillouin gain spectrum（BGS）of our proposed chalcogenide PCF exhibits a multipeaked behavior and has a high Brillouin gain coefficient.We also find that a larger size of inner cladding air holes will lead to a more pronounced second peak in the BGS.On the other hand,the size of the outer cladding has nearly no effect on the BGS behavior.Through these results,one can tailor the Stimulated Brillouin scattering effect in PCFs for a wide range of applications.
文摘Typically, photonic waveguides designed for nonlinear frequency conversion rely on intuitive and established principles, including index guiding and bandgap engineering, and are based on simple shapes with high degrees of symmetry. We show that recently developed inverse-design techniques can be applied to discover new kinds of microstructured fibers and metasurfaces designed to achieve large nonlinear frequency-conversion efficiencies. As a proof of principle, we demonstrate complex, wavelength-scale chalcogenide glass fibers and gallium phosphide three-dimensional metasurfaces exhibiting some of the largest nonlinear conversion efficiencies predicted thus far,e.g., lowering the power requirement for third-harmonic generation by 104 and enhancing second-harmonic generation conversion efficiency by 107. Such enhancements arise because, in addition to enabling a great degree of tunability in the choice of design wavelengths, these optimization tools ensure both frequency-and phase-matching in addition to large nonlinear overlap factors.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 60588502, 60607005, 60877033)the Science and Technology Bureau of Sichuan Province (Grant No. 2006z02-010-3) the Youth Science and Technology Foundation of UESTC (Grant No. JX0628)
文摘A novel asymmetrical twin-core photonic crystal fiber was proposed, whose effective overlap core area Aeff can be designed to synchronize the variation of Raman gain coefficient with respect to frequency. This fiber possesses a higher and flatter Raman gain efficiency coefficient curve rR=gR/Aeff over a specified band of wavelength than a conventional fiber. Therefore, it is a good candidate of gain me- dium for a flat, broad gain band fiber Raman amplifier. It was numerically demonstrated that for the Raman gain efficiency rR, relative fluctuations of less than 2.2% and 5.7% are achievable in the C (1530―1565 nm) band and L (1565―1625 nm) band, respectively.
