Continuously tunable extended cavity diode laser at 780 nm for high resolution spectroscopy

In this communication we have investigated and compared the tuning abilitie s of an ECDL system, using a grating in Littrow configuration, depending on the laser diode (LD) used. We have achieved experimentally a wide continuo us frequency tuning range by applying translation-rotational movement of th e grating together with appropriate injection current correction. The fluor escence spectrum of Rb in the vicinity of 780 nm has been recorded in an ex ternal absorption cell. The wide mode-hop free frequency tuning gave us the possibility to reach exactly the maximum of each fine component of the Rb D-2 line. By scanning the applied magnetic field strength, sub-natural widt h resonance (SNWR), with FWHM in the kHz range, have been observed in the f luorescence signal and in the transmitted output power. Such resonance is v ery appropriate for measuring weak magnetic fields.