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Micro-cell structures with side-walls as thin as 0.70 μm and aspect ratios as high as 6.7 are fabricated by single-layer writing through two-photon-absorption (TPA) photopolymerization. The use of a moderate-numerical-aperture (N.A.) objective lens to obtain a much more elongated voxel and an in situ ultraviolet (UV) pre-exposure step to improve the sensitivity of TPA photopolymerization are the main factors responsible for the high aspect ratio and sub-diffraction-limit resolution that are achieved.

A Yb 3+ :CS-FAP (Yb 3+ :Ca 4 Sr(PO 4 ) 3 F) laser has been actively mode locked to generate pulses as short as 35 ps, which were far from transform limited. Intra cavity pulse compression failed to realise the femtosecond pulse generation potential of this relatively broad bandwidth (∼ 10 nm) and efficient laser material. Site-selective excitation techniques were employed to demonstrate an excitation wavelength-dependent laser emission. This spectral inhomogeneity arises from the disorder on the metal host site which is due to random Ca and Sr occupation. Such a characteristic most likely prohibited ultrashort pulse generation with this sample.

Compact, all-solid-state, femtosecond Cr 4+ :YAG and Cr 4+ :forsterite lasers have been demonstrated. In optimised cavities, self-starting of the mode-locking in Cr 4+ :YAG was observed generating pulse durations of 43 fs, while with Cr 4+ :forsterite, pulses as short as 68 fs were obtained.

Wavelength tuneable pulses of about 100fs duration have been generated through self-mode-locking initiated by synchronous pumping of a c.w. Cr4+ : YAG laser.

We have observed true self-starting Kerr-lens mode locking in two distinct solid-state laser systems operating at room temperature by optimizing the cavity geometry to maximize the amplitude modulation with respect to the intracavity power variation. Pulses of 15 ps have been obtained from a Pr(3+):YLF laser system operating at 607 nm, and 53-fs pulses have been obtained from Cr(4+):YAG at 1.54 microm.

The passive mode locking of a Cr4+:YAG laser generating pulses shorter than 100 fs is described. The cavity group velocity dispersion has been measured and local resonances have been observed which appear to affect the mode locking of the laser.

A compact Cr4+:YAG tunable solid state laser pump source operating broadly around 1.48 µm has been used to pump an Er3+ fibre laser and amplifier. The laser exhibited a 55% slope efficiency and output powers in excess of 21 dBm. At 1.55 µm, the amplifier had a measured gain of 25 dB for a launched pump power of 23.6 dBm. Increased power scaling should be readily achieved.

This paper reviews ultrafast Kerr Lens Mode-locked solid- state lasers with particular emphasis on all-solid-state diode-pumped laser technology which has the potential to provide low-cost compact devices for ultrafast instrumentation, particularly for biomedical applications.We have demonstrated the use of ultrafast solid-state lasers for 3D imaging through turbid media using time-gated photorefractive holography, and for fluorescence lifetime imaging.

The development of Kerr Lens mode-locked (KLM) solid-state lasers [1, 2] has demonstrated the potential for convenient user friendly ultrafast laser systems which may be commercialised and applied in a wide range of scientific and technological areas. Self-starting KLM has recently been shown to be straightforward in Ti: sapphire lasers [3] and may be extended to any other solid-state laser medium to yield a relatively simple picosecond or femtosecond laser with no active components to increase the complexity of the system and no resonant saturable absorbers to compromise the tunability.

Sub-100 fs pulse generation from a Kerr lens modelocked Cr/sup 4+/:YAG laser has been demonstrated for the first time, yielding femtosecond pulses tunable from 1.49 to 1.56 mu m with pulses as short as 90 fs obtained at 1.53 mu m.

We describe a compact, self-mode-locked. Tunable (in the second telecommunications window) all-solid-state. Cr/sup ++/:forsterite laser generating transform limited sub 70 fs pulses.