Fiber laser mode-locked with a semiconductor saturable absorber etalon operating in transmission

We demonstrate a ring cavity ytterbium fiber laser mode-locked with a semiconductor saturable absorber used in transmission. The resonant cavity-enhanced nonlinear response corresponding to the low-loss transmission state enables a robust self-starting mode-locking. Such a transfer function is opposite to that of the resonant absorber operating in the reflection mode, where the highest modulation depth matches the high-loss state. The device ensures ultrashort pulse operation with the wavelength self-adjusted to the optimal value corresponding to the low-loss state of the laser cavity. When using a saturable absorber etalon in transmission mode, the mode-locking mechanism is also highly tolerant to the total cavity dispersion