External Cavity Diode Laser - part 1: optical path and mechanical design
Introduction External cavity diode laser (ECDL) combines benefits of laser diodes and DPSS lasers. The semiconductor chip provides easy to pump, efficient, high gain medium while the external cavity allows tailoring device performance. Wavelength selective elements, like diffraction gratings or etalons can be added to the resonator to reduce emission spectrum, saturable absorber can be added for mode-locking, partially reflective mirror in conjunction with RF modulation can be used for frequency comb generation and many more. In this article, we will try to design simplest, ECDL that'll be used in future experiments so state tuned! How it works There are many great internet sources describing how ECLD works, so let's just quickly recap. Out of the box laser diode has relative wide emission bandwidth, usually around 1-2nm. This is because the gain bandwidth of diode is relative wide and the resonator works with relatively weak coupling (output mirror has reflectivity of 32