Abstract
We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-long cavity provides generation of 16-ps pulses with repetition rates in the GHz range (up to 11.3 GHz) and 12 mW average power. Stable CW mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with a Gires–Tournois interferometer.
Highlights
The development of ultrafast mode-locked (ML) lasers with high repetition rates have attracted great attention because of a growing number of applications
We report the first demonstration of stable multi-GHz repetition rate CW mode-locking of a direct laser-written waveguide laser operating with single-layer graphene saturable absorber
We reported a miniature diode-pumped ultrafast waveguide laser delivering 16 ps pulses at up to 11.5 GHz repetition rate and 12 mW average power at 1064 nm central wavelength
Summary
The development of ultrafast mode-locked (ML) lasers with high repetition rates have attracted great attention because of a growing number of applications. The way to avoid such instabilities through generation of solitons under an additional condition when the gain width spectrum is compatible with the pulse spectral width[16,19,20] has been shown In such circumstances, a negative feedback arises between the soliton energy and the overall pulse gain that in turn leads to a highly stable mode-locking regime for soliton formation in a two-mirror resonator with a length of a few mm, the latter supplemented with a Gires–Tournois interferometer, which provides the appropriate negative group delay dispersion (GDD) for round trip in the cavity[16,20,21]. This method has advantages over other methods of forming the waveguides in providing higher flexibility to produce waveguides with different architectures of refractive index profile, relative simplicity, and less time-consuming process of the waveguide formation[22,23,24,25,26]
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