Zero-power gain measurements in a CW HF laser using a pulsed-probe laser

• Published in: IEEE journal of quantum electronics Vol. 9; no. 5; pp. 550 - 553
• Main Authors: Chodzko, R., Spencer, D., Mirels, H.
• Format: Journal Article
• Language: English
• Published: IEEE 01-05-1973
• Subjects: Fluid flow measurement; Gain measurement; Hafnium; Laser transitions; Optical pulses; Power measurement; Probes; Pulse measurements; Temperature; Vibration measurement
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/JQE.1973.1077512

Zero-power gain measurements in a supersonic diffusion-type CW HF laser have been made using a pulsed HF probe laser. A peak zero-power gain of 10 percent/cm was measured on a P_{2}(3) vibrational-rotational transition and 7 percent/cm on a P_{1}(6) transition for flow rates corresponding to 1.8 kW of closed-cavity power. The variation of zero-power gain with rotational quantum number J fits a simple rotational equilibrium model indicating increasing rotational temperatures with increasing distance x from the nozzle exit plane. The model also indicates a total inversion for x \leq 0.2 in for the P_{2}(J) transitions and a partial inversion further downstream.