Development of a single-frequency fiber–solid hybrid laser operated at the Fraunhofer line of 527.039  nm

A single-frequency laser operated at the Fraunhofer line of 527.039 nm has been demonstrated. Utilizing multi-stage fiber-bulk amplifiers seeded by a distributed feedback laser diode, a fundamental laser emitting at 1054.078 nm was carefully designed to boost the pulse energy to 0.64 mJ at 20 Hz. The 1054.078 nm laser was subsequently frequency-doubled to 527.039 nm. This green laser generated a pulse energy of 0.29 mJ, with a spectrum linewidth of less than 0.4 pm (a resolution limit of the wavelength meter) and a pulse duration of approximately 24 ns. The beam profile was a high-quality <i>T</i><i>E</i><i>M</i>₀₀ mode with an <i>M</i>² factor of less than 1.19.