Abstract

Diode lasers with narrow spectral linewidth and wide spectral coverage are of high importance, such as in metrology, sensing, or as phase reference in optical beam-forming networks (OBFNs) [1]. These desired spectral properties can be achieved via feedback from long external cavities that comprise narrowband spectral filters, so-called external cavity diode lasers (ECDLs) [2]. However choosing free-space optics with bulk components as frequency-selective elements renders such lasers sensitive to acoustic perturbations, while a large physical size is unacceptable for most applications as well. Monolithically integrated lasers, such as distributed Bragg reflector (DBR) lasers and distributed feedback (DFB) lasers avoid such issues but show relatively large linewidths, typically, in the order of MHz [3].

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