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Ultrafast fiber lasers (UFLs) have become an attractive alternative to solid‐state lasers (SSL) due to their excellent beam quality, compactness, environmental stability, and easy thermal management. In the last decade, a significant research effort is spent to identify UFL architectures providing pulse energy, duration, and peak power comparable to those of complex and expensive, Ti:sapphire laser systems and semiconductor saturable absorber mirrors mode‐locked, Yb‐doped SSL. Lately, Mamyshev oscillators (MOs), relying on offset spectral filtering combined with nonlinear spectral broadening by self‐phase modulation, emerge as a promising solution and are rapidly becoming the state of the art for high energy/peak power UFLs based on large‐mode‐area (LMA) fibers. The focus of this work is the first demonstration of starting of the mode‐locking regime in an LMA MO with an affordable passively Q‐switched microchip laser. This solution was previously demonstrated only in low‐power MO based on single‐mode fibers, which are intrinsically easier to seed, if compared to high‐gain LMA UFLs, because of the lower amplified spontaneous emission noise floor. This starting technique in an easy‐to‐implement ring LMA MO at 1 μm is tested. The oscillator provides ≈50 nJ pulses at 12 MHz repetition rate with a minimum pulse duration of ≈50 fs after compression, resulting in MW peak power. |
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