Christian Fiebig

Diode-pumped mode-locked Yb:YCOB laser generating 35 fs pulses

Direct sub-50-fs pulse generation is demonstrated with a mode-locked Yb:YCa4O(BO3)3 laser. With external compression, pulses as short as 35 fs are generated at 1055 nm. The oscillator operating at a repetition rate of 95 MHz is pumped by a two-section distributed Bragg reflector tapered diode laser and mode locked by a semiconductor saturable absorber mirror. The onset of self-Raman-conversion for pulse spectral bandwidths exceeding 40 nm (FWHM) is observed.

Diode-pumped gigahertz femtosecond Yb:KGW laser with a peak power of 3.9 kW

We present a diode-pumped Yb:KGW laser with a repetition rate of 1 GHz and a pulse duration of 281 fs at a wavelength of 1041 nm. A high brightness distributed Bragg reflector tapered diode laser is used as a pump source. Stable soliton modelocking is achieved with a semiconductor saturable absorber mirror (SESAM). The obtained average output power is 1.1 W and corresponds to a peak power of 3.9 kW and a pulse energy of 1.1 nJ. With harmonic modelocking we could increase the pulse repetition rate up to 4 GHz with an average power of 900 mW and a pulse duration of 290 fs. This Yb:KGW laser has a high potential for stable frequency comb generation.

High-Power DBR-Tapered Laser at 980 nm for Single-Path Second Harmonic Generation

We present experimental results about edge-emitting distributed-Bragg-reflector-tapered diode lasers emitting at 980 nm. The investigated lasers show an output power of up to 12 W with a conversion efficiency of about 45%. The lasers also exhibit a small vertical divergence <15deg full-width at half maximum (FWHM), a nearly diffraction-limited beam quality, and a narrow spectral linewidth with FWHM smaller than 12 pm. These properties allow efficient single-pass second harmonic generation with power levels of more than 1 W at 488 nm.

Diode-pumped mode-locked Yb:LuScO(3) single crystal laser with 74 fs pulse duration.

The mode locking of the mixed sesquioxide single crystal Yb:LuScO(3) is demonstrated. This crystal is locally disordered and has the broadest emission spectrum of all sesquioxides known so far. Pulse durations as short as 111 and 74 fs were obtained using the semiconductor saturable absorber mirror and Kerr-lens mode locking, respectively. The latter regime was reached using a two-section distributed Bragg-reflector tapered diode laser as a pump source.

Femtosecond diode-pumped solid-state laser with a repetition rate of 4.8 GHz.

We report on a diode-pumped Yb:KGW (ytterbium-doped potassium gadolinium tungstate) laser with a repetition rate of 4.8 GHz and a pulse duration of 396 fs. Stable fundamental modelocking is achieved with a semiconductor saturable absorber mirror (SESAM). The average output power of this compact diode-pumped solid state laser is 1.9 W which corresponds to a peak power of 0.9 kW and the optical-to-optical efficiency is 36%. To the best of our knowledge, this is the femtosecond DPSSL with the highest repetition rate ever reported so far.

Diode pumped high power operation of a femtosecond laser inscribed Yb:YAG waveguide laser [Invited]

Waveguides were written into single crystalline Yb(7%):YAG with a femtosecond laser. Laser oscillation of the waveguides without external mirrors at an output coupling transmission of 99% was demonstrated. The laser performance of the waveguide lasers, pumped with various light sources, was examined. With an optically pumped semiconductor laser (OPS) as pump source a slope efficiency of 51% regarding incident pump power and a maximum output power of 1.76 W could be achieved. By using a high brightness DBR tapered diode laser as pump source the possible miniaturization of the waveguide laser device was demonstrated. With this pump source even 2.35 W of output power from the waveguide laser was achieved. The beam quality at highest output power turned out to be excellent with an M2-factor of less than 1.3.

Graphene mode-locked femtosecond Yb:KLuW laser

Large-area monolayer graphene, synthesized by chemical vapor deposition, was transferred to a 1-in. quartz substrate. The high-quality monolayer graphene has been subject to characterization of the nonlinear properties near 1 μm and was successfully applied as saturable absorber for passive mode-locking of a femtosecond Yb:KLuW laser. The diode-pumped mode-locked Yb:KLuW laser was tunable around 1.04 μm and delivered pulses as short as 160 fs. The maximum output power of 160 mW was demonstrated for 203 fs pulse duration. The mode-locked laser results are comparable to those demonstrated with the same laser gain medium using single-walled carbon nanotubes as saturable absorbers.

42-fs diode-pumped Yb:Ca4YO(BO3)3 oscillator.

We demonstrate a passively mode-locked femtosecond laser based on the self-frequency-doubling crystal Yb:Ca4YO(BO3)3. The oscillator is pumped by a novel two-section distributed Bragg-reflector tapered diode-laser. Pulses as short as 46 fs and 42 fs at 1050 nm are achieved for the E//Z polarization without and with external compression, respectively. These are, to the best of our knowledge, the shortest pulses obtained from an oscillator based on Yb3+-doped bulk material.

Compact second-harmonic generation laser module with 1 W optical output power at 490 nm

We demonstrate continues-wave 1 W at 490 nm on a 2.5 cm(3) micro-optical bench using single-path second-harmonic generation with a periodically poled MgO:LiNbO(3) bulk crystal. The pump laser is a distributed Bragg reflector tapered diode laser having a single-frequency spectrum and a pump power of 9.5 W. Based on that 1 W blue light could be achieved resulting in an optical conversion efficiency of 11%. Furthermore, the module has an output power stability of better than 2% and the blue laser beam shows an nearly diffraction limited beam quality of M(2)(sigma) = 1.2 in vertical and M(2)(sigma) = 2 in lateral direction.

High-power distributed Bragg reflector ridge-waveguide diode laser with very small spectral linewidth

We manufactured and investigated distributed Bragg reflector ridge-waveguide diode lasers having sixth-order surface gratings and an emission wavelength around 974 nm. The single-mode output power of the lasers with a total length of 4 mm exceeded 1 W. A very small spectral linewidth of 1.4 MHz (3 dB) consisting of a Lorentzian part of 146 kHz and a Gaussian part of 1308 MHz was measured using a self-delayed heterodyne measurement technique.