A 7.8-μm surface emitting second-order distributed feedback quantum cascade laser （DFB QCL） structure with metallized surface grating is studied. The modal property of this structure is described by utilizing coupl...A 7.8-μm surface emitting second-order distributed feedback quantum cascade laser （DFB QCL） structure with metallized surface grating is studied. The modal property of this structure is described by utilizing coupled-mode theory where the coupling coefficients are derived from exact Floquet-Bloch solutions of infinite periodic structure. Based on this theory, the influence of waveguide structure and grating topography as well as device length on the laser performance is numerically investigated. The optimized surface emitting second-order DFB QCL structure design exhibits a high surface outcoupling efficiency of 22% and a low threshold gain of 10 cm-1. Using a π phase-shift in the centre of the grating, a high-quality single-lobe far-field radiation pattern is obtained.展开更多
We demonstrate surface emitting distributed feedback quantum cascade lasers emitting at wavelengths from 8.1 μm at 90 K to 8.4 μm at 210 K. The second？order metalized grating is carefully designed using a modified ...We demonstrate surface emitting distributed feedback quantum cascade lasers emitting at wavelengths from 8.1 μm at 90 K to 8.4 μm at 210 K. The second？order metalized grating is carefully designed using a modified coupled-mode theory and fabricated by contact lithography. The devices show single mode behavior with a side mode suppression ratio above 18 dB at all working temperatures. At 90 K, the device emits an optical power of 101 mW from the surface and 199 mW from the edge. In addition, a double-lobe far-field pattern with a separation of 2.2° is obtained in the direction along the waveguide.展开更多
基金Project supported by the National Science Fund for Distinguished Young Scholars of China (Grant No. 60525406)the National Natural Science Foundation of China (Grant Nos. 60736031,60806018,and 60906026)+1 种基金the National Basic Research Program of China (Grant No. 2006CB604903)the National High Technology Research and Development Program of China (Grant Nos. 2007AA03Z446 and 2009AA03Z403)
文摘A 7.8-μm surface emitting second-order distributed feedback quantum cascade laser （DFB QCL） structure with metallized surface grating is studied. The modal property of this structure is described by utilizing coupled-mode theory where the coupling coefficients are derived from exact Floquet-Bloch solutions of infinite periodic structure. Based on this theory, the influence of waveguide structure and grating topography as well as device length on the laser performance is numerically investigated. The optimized surface emitting second-order DFB QCL structure design exhibits a high surface outcoupling efficiency of 22% and a low threshold gain of 10 cm-1. Using a π phase-shift in the centre of the grating, a high-quality single-lobe far-field radiation pattern is obtained.
基金Supported by the National Science Fund for Distinguished Young Scholars of China under Grant No 60525406, the National Natural Science Foundation of China under Grant Nos 60736031, 60806018 and 60906026, the National Basic Research Program of China under Grant No 2006CB604903, and the National High Technology Research and Development Program of China under Grant Nos 2007AA03Z446 and 2009AA03Z403.
文摘We demonstrate surface emitting distributed feedback quantum cascade lasers emitting at wavelengths from 8.1 μm at 90 K to 8.4 μm at 210 K. The second？order metalized grating is carefully designed using a modified coupled-mode theory and fabricated by contact lithography. The devices show single mode behavior with a side mode suppression ratio above 18 dB at all working temperatures. At 90 K, the device emits an optical power of 101 mW from the surface and 199 mW from the edge. In addition, a double-lobe far-field pattern with a separation of 2.2° is obtained in the direction along the waveguide.
