Efficient Dual-Wavelength Synchronously Mode- Locked Picosecond Laser Operating on the 4F 3/2 → 4I11/2 Transition With Compactly Combined Dual Gain Media

Abstract

A novel concept based on the dual gain media is originally proposed for achieving a compact efficient dual-wavelength synchronously mode-locked diode-end-pumped Nd laser on the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3/2</sub> → <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11/2</sub> transition. We theoretically and experimentally realize that the output power ratio between two spectral outputs could be flexibly controlled simply by varying the waist position of the pump beam inside the composite gain medium. With the developed tactic, the total output power at 1.06 μm for balancing two-color intensities reaches 2.9 W. Moreover, suppressing the excitation of a few high-order transverse modes enables a fairly stable picosecond pulse train to be achieved with the self mode locking, where the mode-locked pulse width and repetition rate are measured to be 47 ps and 2.86 GHz, respectively. A series of 0.32 THz ultrashort pulses with the effective duration of 1.6 ps is further generated through the optical beating between two carrier frequencies of dual-wavelength synchronous pulses.