Passive mode locking of the Ar(+) laser.

Area of Science:

• Optics and Photonics
• Laser Physics
• Nonlinear Optics

Background:

• Passive mode locking is crucial for generating ultrashort laser pulses.
• Saturable absorbers like rhodamine 6G are key components in mode-locked lasers.
• Argon (Ar) ion lasers are widely used in scientific research.

Purpose of the Study:

• To investigate passive mode locking of an Ar(+) laser using rhodamine 6G.
• To compare four different operating regimes: colliding pulse and conventional, with and without double mode locking.
• To analyze the Ar(+) and dye laser pulses generated by the double mode-locked Ar(+)-dye laser system.

Main Methods:

• Utilized correlation measurements to investigate laser pulses.
• Employed a rhodamine 6G saturable absorber.
• Configured the Ar(+) laser in both colliding pulse and conventional modes.
• Incorporated double mode locking in specific configurations.

Main Results:

• Direct measurement of a 67-picosecond (ps) Ar(+) pulse shape was achieved.
• Parametric studies provided insights into pulse generation mechanisms.
• The colliding pulse regime, with coherent interaction of Ar(+) pulses in the saturable absorber, was identified.
• This regime demonstrated superior stability and shorter pulse durations.

Conclusions:

• The colliding pulse regime with double mode locking is favorable for Ar(+) laser systems.
• Understanding pulse formation mechanisms is essential for optimizing laser performance.
• Rhodamine 6G is an effective saturable absorber for Ar(+) laser mode locking.