Characterization of Yb–Er:glass lasers at 1.5 μm wavelength in terms of amplitude and frequency stability

Abstract

The 1.5 μm ytterbium–erbium laser was extensively investigated in terms of its intensity and frequency noise characteristics. The energy transfer process between Yb and Er ions in the codoped active material was shown to reduce substantially the intensity noise induced by pump power fluctuations. To further suppress the intensity noise, a suitable control loop acting on the injection current of the pump laser diode was employed, providing for a 30-dB reduction of the relaxation oscillation peak. Some high-resolution laser spectroscopy measurements have been performed on the acetylene molecule by means of the tunable Yb–Er microlaser. Frequency locking and stabilization was achieved by both the fringe-side locking technique and the FM side-band technique, using different rovibrational lines of the C 2H 2. The beat note between two independently stabilized diode-pumped Yb–Er:glass lasers, operating at 1534.097 nm wavelength, yielded a long-term frequency stability of 170 kHz with an Allan standard deviation below 10 −10 for integration times between 10 ms and 1 s.