KE-CVL:

Kinetically-enhanced high power copper vapor lasers (KE-CVL) are the recently developed CVL systems with high efficiency (1.2-1.5%). This is accomplished by operating the CVLs at higher rep-rate ( 9- 20 kHz) and using special gas mixture consisting of ~ 0.5% HCl , 1-2% Hydrogen and Neon as balance. The presence of HCl favorably controls the electron density in the discharge mainly by the process of dissociative-attachment, thus ensuring most favorable excitation conditions in the copper vapour laser. Based on this concept, a high power CVL was developed capable of delivering 100 W average laser power. The laser was operated at 10- kHz rep-rate at a total input power of 7.5 kW with an overall electro-optic efficiency of about 1.4%. The laser requires about one hour to reach maximum power after threshold lasing. The near field pattern of beam shape is Hat-Top type with higher intensity at the centre.

KE-CVL MOPA configuration :

Single stage KE-CVL MOPA configuration involving two KE-CVL units was successfully demonstrated with maximum output power of ~ 130 W ( single beam ),Gain durations were mapped and other related R& D was carried out . Overall efficiency of MOPA was ~ 2 % . Further work is in progress consisting of 3 KE-CVL units.

Beam quality improvement and new resonator designs in KE-CVL

To exploit fully the KE-CVL properties the new resonator designs were proposed and demonstrated based on various new and novel configurations as listed below. The main objective was to achieve high optical extraction with low beam divergence and high misalignment tolerance simultaneously which otherwise are difficult to achieve from standard configurations.

Following new resonator configurations were proposed and implemented with interesting and useful results.

1. Stable-unstable  hybrid  resonator for high  magnifications,  M > 1000
2. Diffraction coupled  resonator ( DCR ) using dot mirrors  for higher feedback.
3. General CAT-EYE resonators  for high misalignment tolerance
4. Unstable CAT-EYE resonator  with intra-cavity apertures.
5. Stable CAT-EYE resonator

In each of the above resonators the optical extraction was ~ 70-75 % , beam divergence ~ 0.15 mrad and high misalignment tolerance ~ 5- 6 mrad.

PROFILE OF KE-CVL

• High electro-optic efficiency : 1.5 % (Wall plug )
• High specific output power
• Scalable to large diameters
• Standard CVLs can be converted to KE-CVLs
• High beam quality as compared to standard CVLs
• Sealed off (No flow of buffer gas) operation possible
• Long output pulses : 50-60 ns fwhm