Wide bandwidth (100)GaAs/fluorides quarter-wavelength Bragg reflectors grown by molecular beam epitaxy

Broadband quarter-wavelength Bragg reflectors that consist of periodic stacks of fluorides (CaF2-BaF2-CaF2) and GaAs, centered at 1.4 mu m, were grown by molecular beam epitaxy. Despite a total fluoride thickness as high as 720 nm, crack-free surface morphology was obtained. In this letter, we report a crack-free standard quarter-wavelength III-V semiconductor-fluoride Bragg reflector. With only three stacks, the bandwidth with reflectance above 95% is about 650 nm (1.15-1.80 mu m), while, near the center wavelength, the reflectivity is as high as 99%. Both important wavelengths of 1.3 and 1.55 mu for optical communication are included in the very wide high reflectance plateau. These mirrors are expected to have wide applications for optical and optoelectronic devices. (C) 1996 American Institute of Physics.