FIG 2 (IMAGE) Compuscript Ltd Caption Fig. 2 (a) Typical transmission signal of the QCL through a reference gas cell filled with CO; (b) Variation of QCL linewidth with the feedback rate; (c) Comparison of cavity-transmitted signals obtained with different optical feedback rates. Credit OEA Usage Restrictions Credit must be given to the creator. License CC BY Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.