All-solid-state 3-µm single-frequency Er:CaF₂ laser with a stable and switchable wavelength

Area of Science:

• Laser Physics
• Solid-State Lasers
• Infrared Optics

Background:

• Single-frequency lasers are crucial for various scientific and technological applications.
• Developing efficient and stable lasers in the 3-µm wavelength region presents significant challenges.
• Erbium-doped calcium fluoride (Er:CaF2) is a promising material for mid-infrared laser development.

Purpose of the Study:

• To demonstrate a novel 3-µm all-solid-state single-frequency laser.
• To achieve stable center frequency and switchable wavelengths.
• To explore direct diode pumping of Er:CaF2 for single-frequency laser applications.

Main Methods:

• Utilized an intra-cavity Fabry-Perot etalon for wavelength selection and stabilization.
• Employed direct diode laser pumping of Er:CaF2 block single crystals.
• Characterized laser output power, central wavelength stability, and single-longitudinal mode linewidth.

Main Results:

• Achieved single-frequency laser operation at 2728 nm and 2794 nm.
• Obtained maximum output powers of 268 mW and 440 mW, respectively.
• Measured single-longitudinal mode linewidths of 25 MHz and 11 MHz, with stable central wavelengths across pump power variations.

Conclusions:

• Successfully demonstrated the first direct diode-pumped Er:CaF2 single-frequency laser in the 3-µm region.
• The developed laser exhibits stable operation and switchable wavelengths.
• This work represents a significant advancement in high-power, all-solid-state 3-µm single-frequency lasers.