Full text loading...
(a) Scheme of the studied structure with a grating depth ( is the grating period) and the upper cladding thickness . The profile of the uncoupled waveguide mode and surface mode are presented in gray strips. (b) Exact calculation performed with an -matrix algorithm of the dispersion diagram at the FBZ edge. The Bragg component of the grating opens a photonic band gap at outside the light line and the second order component couples the two branches ( in red squares and in blue circles) in the light lines at .
(a) Radiation losses for both and . Simulations (blue circles for and red squares for ) and the model described by Eq. (5) (blue and red lines for and , respectively) are shown. Inset: evolution of vs (red line and squares for the , and blue line and circles for bands). (b) Simulations of the radiative losses vs the grating depth for the biperiodic grating (blue circles for and green squares for both for ) and for a second order grating alone (red triangles for a grating duty cycle of and black stars for ).
Far field pattern for a 2 mm long and wide device. The color bar is in arbitrary units. The panel maps the optical intensity on and .
and are plotted for a 2 mm long and wide device. The laser was driven with a repetition rate of 5 kHz and 100 ns pulse width. The inset shows a double-mode spectrum of the same QCL taken at room temperature.
Article metrics loading...