Mode locking with a slow saturable absorber in a transverse resonator

Area of Science:

• Optics and Photonics
• Laser Physics

Background:

• Mode-locking is crucial for generating ultrashort laser pulses.
• The selection of suitable saturable absorbers limits the performance and applicability of mode-locked lasers.
• Existing techniques often restrict the range of dyes usable as saturable absorbers.

Purpose of the Study:

• To introduce a new mode-locking technique that expands the palette of dyes usable as saturable absorbers.
• To demonstrate the efficacy of this technique in achieving efficient mode-locking.
• To explore the potential applications of this method in both visible and ultraviolet laser systems.

Main Methods:

• Enclosing a saturable absorber dye within a high-Q transverse resonator.
• Utilizing stimulated emission to reduce the absorber's effective lifetime.
• Employing rhodamine 6G as the amplifier and cresyl violet as the saturable absorber for demonstration.
• Investigating the application for mode-locking visible dye lasers and ultraviolet excimer lasers.

Main Results:

• The technique significantly broadens the range of dyes applicable as saturable absorbers.
• The high-Q resonator effectively reduces the absorber lifetime via stimulated emission, ensuring complete recovery between passes.
• Successful demonstration of mode-locking using rhodamine 6G and cresyl violet.
• The method shows potential for mode-locking ultraviolet excimer lasers (e.g., KrF, XeCl) with visible dyes.

Conclusions:

• This new mode-locking approach overcomes previous limitations in saturable absorber selection.
• The technique offers a versatile and effective method for mode-locking various laser types.
• It holds significant promise for advancing laser technology, particularly in visible and UV spectral regions.