We proposed a new type of distributed feedback laser with alternating active- and passive-cavities (APC DFB). which enjoys the same quantum well layer where the butt-joint re-growth process can be avoided. By utilizing the chirp characteristics of the APC DFB laser in a delayed self-heterodyne system. a chirped microwave signal with a sweep range up to 40 GHz and a sweep period of 25 ... https://www.roneverhart.com/Ray-Ban-RB3519-59mm/