Quantum-dot Saturable Absorber Mirror Research Articles

Diode-pumped ultrafast Yb:KGW laser with 56 fs pulses and multi-100 kW peak power based on SESAM and Kerr-lens mode locking

A high-power sub-60 fs mode-locked diode-pumped Yb:KGW laser based on hybrid action of an InGaAs quantum-dot saturable absorber mirror and Kerr-lens mode locking was demonstrated. The laser delivered 56 fs pulses with 1.95 W of average power corresponding to 450 kW of peak power. The width of the generated laser spectrum was 20.5 nm, which was near the gain bandwidth limit of the Yb:KGW crystal. To the best of our knowledge, these are the shortest pulses generated from the monoclinic double tungstate crystals (and Yb:KGW laser crystal in particular) and the most powerful in the sub-60 fs regime. At the same time, they are also the shortest pulses produced to date with the help of a quantum-dot-based saturable absorber. High-power operation with a pulse duration of 90 fs and 2.85 W of average output power was also demonstrated.

Gigahertz repetition rate mode-locked Yb:KYW laser using self-assembled quantum dot saturable absorber

Fundamental mode-locking is achieved in a 1.036 GHz cavity using a semiconductor quantum dot saturable absorber mirror with a fast relaxation time component of down to 550 fs. The dispersive cavity delivers 1.7 ps wide pulses with spectra supporting sub-picosecond pulse durations and an M² of 1.3. An average output power of up to 339 mW at wavelengths around 1,032 nm is achieved and the saturable absorber’s damage threshold is identified as a limitation for further power scaling.

Post-growth tailoring of quantum-dot saturable absorber mirrors by chemical etching

We have designed and grown a resonant, low-finesse quantum-dot saturable absorber mirror and subsequently modified the important parameters using chemical etching. The modulation depth and saturation fluence at the design wavelength of 1064 nm were modified by etching the sample to tune the cavity resonance. The device properties were characterised using normal incidence spectroscopic reflectivity measurements, intensity dependent reflectivity measurements and modelled using a transfer matrix approach. The saturable absorber mirror was used to facilitate self-starting, passively mode locked pulses in a neodymium vanadate laser operating at 1064 nm. The etching was found to affect the duration of the pulses, leading to temporal width tuning over a range of 94 ps. The shortest pulse duration of 84 ps was achieved for the cavity resonance close to 1064 nm, with an output power of 3 W. This method is an effective technique for post-growth engineering of the properties of semiconductor saturable absorber mirrors (SESAMs) with nanometre precision.

Quantum dot saturable absorber for passive mode locking of Nd:YVO4 lasers at 1064 nm

An InAs/GaAs quantum dot saturable absorber mirror was used to mode lock a Nd:YVO4 solid-state laser at the operation wavelength of 1064.6 nm. Multi-watt average power was obtained during stable cw mode locking with pulses as short as 24 ps, and with a repetition rate of 65 MHz.

Semiconductor quantum-dot saturable absorber mode-locked fiber laser

We demonstrate self-starting passive mode-locking of an ytterbium fiber laser by using a multilayer quantum-dot saturable absorber mirror. A high modulation depth of the absorber ensures robust pulse operation of the fiber laser with a threshold pump power of 30 mW. The 2.8-ps pulses with an average power of 5 mW have been generated at 1042 nm.

Quantum-dot-based saturable absorber with p-n junction for mode-locking of solid-state lasers

We demonstrate stable mode-locking in a Yb : KYW laser by using a quantum-dot (QD) saturable absorber structure that incorporates a p-n junction. A reduction in the output pulse duration was measured when a reverse bias was applied to the QD saturable absorber mirror.