Asymmetric double QW superluminescent diodes for broadband and high‐power use

We report the use of broadband and high‐power InGaAs/GaAs asymmetric double quantum‐well (ADQW) superluminescent diodes (SLDs), which consist of a tilted, bent, and straight waveguide. To examine the effects of the arrangement of the ADQW and the gain provided by a straight waveguide on the output performances, we fabricated SLDs with different lengths for two types of ADQW, that is, a wide QW at the p‐side for Sample 1, and a narrow QW at the p‐side for Sample 2, and tested their spectral width and output power. The fabricated SLDs with a straight length (L 3 ) of 80 μm show −3 dB spectral widths of 122 and 116 nm and output powers of 20 and 16 mW at an injection current of 250 mA for Samples 1 and 2, respectively. For both samples, it appears that, as the L 3 increases, the spectral width decreases and the output power increases. From this result, we confirmed that both the spectral width and the output power can be adjusted and optimized at a given structure for various applications.