A.A. Lagatsky

Pulsed laser operation of Yb-doped KY(WO 4 ) 2 and KGd(WO 4 ) 2

Spectroscopic properties and laser performance of Y b-doped tungstates at pulsed Ti:sapphire laser pumping are reported. Room-temperature lasing near 1025nm is demonstrated in Yb:KY(WO(4))(2) and Yb:KGd(WO(4))(2), with a slope efficiency as great as 86.9%.

The development and application of femtosecond laser systems

Some background as well as recent progress in the development of femtosecond lasers are discussed together with a brief outline of a few representative emergent applications in biology and medicine that are underpinned by access to such sources. We also provide a short summary of other contributions in this focus issue.

Yb3+-doped YVO4 crystal for efficient Kerr-lens mode locking in solid-state lasers

We report the first demonstration, to our knowledge, of soft-aperture Kerr-lens mode locking in a diode-pumped femtosecond Yb3+:YVO4 laser. Near-transform-limited pulses as short as 61 fs are generated around a center wavelength of 1050 nm with an output power of 54 mW and a pulse repetition frequency of 104.5 MHz. This is, to our knowledge, the shortest pulse generated directly from an Yb laser having a crystalline host material. The femtosecond operation has a mode-locking threshold at an absorbed pump power of 190 mW. The nonlinear refractive indexes of the Yb3+:YVO4 crystal have been measured to be 19 x 10(-16) cm2/W and 15 x 10(-16) cm2/W for the sigma and pi polarizations, respectively, at 1080 nm.

Diode-pumped CW lasing of Yb:KYW and Yb:KGW

Abstract Room temperature CW laser action of Yb 3+ -doped KY(WO 4 ) 2 and KGd(WO 4 ) 2 crystals at 1026–1044 nm has been demonstrated under pumping by 980 nm fiber-coupled InGaAs laser diode. A slope efficiency of Yb lasers up to 53% has been obtained.

Passive Q switching and self-frequency Raman conversion in a diode-pumped Yb:KGd(WO(4))(2) laser.

We report on the laser performance of a diode-pumped Yb:KGd(WO(4))(2) laser that is passively Q switched with a Cr(4+):YAG saturable absorber. Raman conversion of fundamental laser emission in the laser crystal was demonstrated. Q-switched 3.4-mu;J pulses with a pulse width of 85 ns were obtained at the 1033-nm fundamental wavelength and 0.4-mu;J pulses with a pulse width of 20 ns were produced in a first Stokes at 1139 nm.

Ultrafast laser inscribed Yb:KGd(WO4)2 and Yb:KY(WO4)2 channel waveguide lasers.

We demonstrate laser action in diode-pumped microchip monolithic cavity channel waveguides of Yb:KGd(WO(4))(2) and Yb:KY(WO(4))(2) that were fabricated by ultrafast laser writing. The maximum output power achieved was 18.6 mW with a threshold of approximately 100 mW from an Yb:KGd(WO(4))(2) waveguide laser operating at 1023 nm. The propagation losses for this waveguide structure were measured to be 1.9 dBcm(-1).

Highly efficient and low threshold diode-pumped Kerr-lens mode-locked Yb:KYW laser

We report a highly efficient diode-pumped femtosecond Yb:KYW laser with a compact three-element resonator. Near-transform-limited pulses of 107fs duration at a centre wavelength of 1056nm are produced at a pulse repetition frequency of 294MHz by utilising softaperture Kerr-lens mode locking. The femtosecond operation had a modelocking threshold at a pump power of 250mW and the laser was tunable from 1042nm to 1075nm. The optical-to-optical conversion efficiency exceeded 50% in this femtosecond-pulse regime.

2 μm solid-state laser mode-locked by single-layer graphene

We report a 2 μm ultrafast solid-state Tm:Lu2O3 laser, mode-locked by single-layer graphene, generating transform-limited ∼410 fs pulses, with a spectral width ∼11.1 nm at 2067 nm. The maximum average output power is 270 mW, at a pulse repetition frequency of 110 MHz. This is a convenient high-power transform-limited ultrafast laser at 2 μm for various applications, such as laser surgery and material processing.

Femtosecond (191 fs) NaY(WO4)2 Tm,Ho-codoped laser at 2060 nm.

We report, for the first time to our knowledge, femtosecond-pulse operation of a Tm,Ho:NaY(WO(4))(2) laser at around 2060 nm. Transform-limited 191 fs pulses are produced with an average output power of 82 mW at a 144 MHz pulse repetition frequency. Maximum output power of up to 155 mW is generated with a corresponding pulse duration of 258 fs. An ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror is used for passive mode-locking maintenance.

Femtosecond pulse operation of a Tm,Ho-codoped crystalline laser near 2 μm

We demonstrate, for the first time to our knowledge, femtosecond-regime mode locking of a Tm,Ho-codoped crystalline laser operating in the 2 microm spectral region. Transform-limited 570 fs pulses were generated at 2055 nm by a Tm,Ho:KY(WO(4))(2) laser that produced an average output power of 130 mW at a pulse repetition frequency of 118 MHz. Mode locking was achieved using an ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror.