Fiber-optic transmission of stretched pulses from a Q-switched ruby laser

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Fiber-optic transmission of Q-switched ruby laser pulses is limited by fiber damage due to high peak intensities.
• High laser-beam intensities pose a significant challenge for transmitting pulsed laser light through optical fibers, potentially causing damage.

Purpose of the Study:

• To investigate methods for overcoming fiber damage limitations in transmitting Q-switched ruby laser pulses.
• To explore the feasibility of pulse stretching to reduce peak intensities and enable higher energy transmission.
• To assess the transmission characteristics and energy limits of stretched laser pulses in optical fibers.

Main Methods:

• Utilized a semiconductor-based control circuit to modify the Pockels cell of a ruby laser, enabling pulse stretching.
• Generated stretched pulses with durations ranging from 200 nanoseconds (ns) to 1 microsecond (μs).
• Coupled these stretched pulses into multimode optical fibers (600-μm core diameter quartz fibers) to study transmission.

Main Results:

• Successfully generated stretched Q-switched ruby laser pulses with durations of 200 ns to 1 μs and a coherence length of approximately 3 meters.
• Demonstrated that stretched pulses can be transmitted in quartz fibers to pulse energies of 300 millijoules (mJ).
• Achieved a fourfold increase in transmittable pulse energy compared to standard Q-switched pulses, mitigating fiber damage.

Conclusions:

• Pulse stretching is an effective technique to reduce peak intensities of Q-switched ruby laser pulses, enabling higher energy transmission through optical fibers.
• The enhanced energy transmission capacity facilitates the use of fiber optics for ruby laser applications.
• This advancement is expected to significantly aid the application of holographic interferometry in technical fields like vibration analysis.