Diode-pumped Tm:YAP laser operating at 2.3 µm with enhanced performance through cascade lasing

Area of Science:

• Laser Physics
• Solid-State Lasers
• Quantum Electronics

Background:

• Thulium (Tm³⁺)-doped lasers are crucial for mid-infrared applications.
• Achieving high continuous wave (CW) output power at ~2.3 µm remains a challenge.
• Cascade lasing in Tm³⁺ offers potential for enhanced power and efficiency.

Purpose of the Study:

• To investigate the performance of a laser diode (LD)-pumped Tm:YAP laser at ~2.3 µm.
• To evaluate the impact of cascade lasing on output power and efficiency.
• To establish a new benchmark for CW ~2.3 µm Tm³⁺-doped lasers.

Main Methods:

• Utilized a laser diode (LD) for pumping a Tm:YAP (a-cut, 3.5 at.%) crystal.
• Operated the laser in a continuous wave (CW) mode.
• Investigated simultaneous operation on Tm³⁺ transitions (³H₄ → ³H₅ and ³F₄ → ³H₆) for cascade lasing.

Main Results:

• Achieved a maximum CW laser output power of ~3 W at ~2.3 µm.
• Demonstrated that cascade lasing significantly enhances output power.
• Increased the slope efficiency from 13.0% to 21.4% under cascade operation.
• Reported the highest CW output power for LD/Ti:Sapphire-pumped ~2.3 µm Tm³⁺ lasers to date.

Conclusions:

• Laser diode-pumped Tm:YAP lasers are effective for generating high-power ~2.3 µm CW output.
• Cascade lasing is a key mechanism for improving power and efficiency in these systems.
• This work sets a new performance record for ~2.3 µm Tm³⁺ lasers.