Actively Q-switched mode-locked Yb-doped fiber laser with high mode-locking contrast

Abstract

Reliable Q switched and mode locked operation of Yb doped fiber lasers is investigated by employing an acousto optic modulator (AOM) in a linear cavity configuration. The widths and shapes of the Q switched envelopes mainly depend on the external modulation frequency of the AOM and near symmetric Q switched pulses can be generated. Within the Q switched envelopes, harmonic mode locked pulses with near 100% modulation depth at the 40 MHz repetition rate are experimentally observed.

Characteristics of a low repetition rate passively mode-locked Yb-doped fiber laser in an all-normal dispersion cavity

“…The QML operation state has been observed in diodepumped solid-state lasers (DPSSLs) and Yb-doped fiber lasers by means of a passive modulator such as the semiconductor saturable absorber mirror [4,19] or an active modulator such as the acousto-optic modulator [20,21]. As from the experimental reports [4,19] and theoretical prediction [22], by means of a saturable absorber, the QML state can be observed before the complete ML pulse generation in DPSSL with SESAM.…”

“…Expanded single QML envelope at (a) 129 mW and (b)Figures 3(a) and (b) show the expanded time traces of a single QML envelope under which the mode-locked pulses can be obviously seen. By fitting with the formula[21] …”

High peak power sub-nanosecond mode-locked pulse characteristics of Nd:GGG laser

“…The wider the pulse width of the Q-switched envelope, the more the number of the mode-locking in a Q-switched envelope. The theoretical and experimental results show also that the pulse width of the Q-switched envelope decreases with increasing pump power due to the increase of the population inversion density of unit time in laser medium [11]. Moreover, by using the active modulator and the passive saturable absorption, the stably dual-loss-modulated QML pulses with the high energy and the optional repetition rate can be generated [13,14].…”

“…Besides the Q-switched and mode-locked pulse generation in an all normal dispersion Yb-doped fiber laser based on the active and passive modulator has been reported [11,12]. The interval of two neighboring mode-locking pulses in QML lasers equals the cavity roundtrip transmit time.…”

Short-wavelength Yb:fiber laser analysis

“…Secondly, the high quantum efficiency (>90%) of the Yb:fiber laser [2] leads to lower heat load in the host and makes a high power laser with M 2 ∼ 1 possible [3]. Thirdly, the very wide emission band, 900-1200 nm [4], can be applied to tunable lasers [5,6] and mode-locked lasers [7][8][9]. The 980 nm emission is interesting for use in the pumping of high power core-pumped Er-doped fiber oscillators and amplifier lasers.…”