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Quasi‐one‐dimensional metal (q‐1D) K0.3MoO3, exhibits so‐called Peierls transition to a charge density wave (CDW) state with periodic charge density modulation and concomitant lattice distortion at a transition temperature Tp=180 K. Despite the fact that the physical properties of q‐1d bulk materials have been widely investigated, they can drastically change due to reduced dimensionality if the material is in the form of thin film. We present results of the production of K0.3MoO3 thin films by pulsed laser deposition (PLD). Standard characterization techniques showed that our films are composed of nano‐sized metallic grains and presence of CDW in grains was unambiguously proved by femto‐second time resolved spectroscopy (fs‐Trs). This technique also showed that the amplitude mode appears in films at a temperature that is some 30 K lower than in the crystal. Transport measurements in a wide temperature range indicated smeared Peierls transition in some films, at a temperature that is some 30 K lower than in bulk, which is in accordance with fs‐Trs. We have established a connection between film morphology and resistance, namely films with better ordering show lower resistance and more pronounced anomaly at 150 K. Furthermore, our films appear to be well fit by variable range hopping conductivity (VRH) in the almost entire temperature range, which is a characteristic of disordered materials.

An efficient continuous wave and passively mode-locked thulium-doped oxyorthosilicate Tm:LuYSiO5 laser is demonstrated. A maximum slope efficiency of 56.3% is obtained at 2057.4 nm in continuous wave operation regime. With an InGaAs quantum well SESAM, self-starting passively mode-locked Tm:LuYSiO5 laser is realized in the 1929 nm to 2065 nm spectral region. A maximum average output power of 130.2 mW with a pulse duration of 33.1 ps and a repetition rate of about 100 MHz is generated at 1984.1 nm. Pulses as short as 24.2 ps with an average output power of 100 mW are obtained with silicon prisms where used to manage the intracavity dispersion. The shortest pulse duration of about 19.6 ps is obtained with an average output power of 64.5 mW at 1944.3 nm.

The first thin-film growth of the “blue bronze”, oxide X0.3MoO3, well-known for its charge density wave (CDW) ground state, with X=Rb was realized a decade ago by pulsed laser deposition (PLD). However, the deposition of X=K blue bronze thin films was successfully realized only last year. The relevant parameters for successful PLD are the repetition rate, the fluence, the number of pulses, the distance between the target and the substrates, the substrate temperature and the oxygen pressure. Keeping all other parameters constant, we have varied the oxygen pressure between 0.01 mbar and 0.1 mbar and the substrate temperature between 375 °C and 450 °C with several attempts at 350 °C and 500 °C. Here we present the optimal conditions in p-T parameter space for the pulsed laser deposition of K0.3MoO3 films based on the characterization by several standard methods.

Thin granular films of charge density wave (CDW) system K0.3MoO3 were prepared by pulsed laser deposition and investigated by various standard characterization methods such as GI-XRD, electric transport, TOF-ERDA, AFM and UV-vis spectroscopy. While all these methods indicate that the thin films consist of nanometer grains of K0.3MoO3, it is only the non-destructive femtosecond time-resolved spectroscopy (fsTRS) that demonstrates the charge density wave nature of the ground state and therefore proves directly the presence of K0.3MoO3. Furthermore, the comparison of the fsTRS data obtained in thin films and in single crystals shows the reduction of the charge density wave transition temperature and of the photoinduced signal strength in granular thin films in respect to single crystals, which is attributed to the granularity and crystal growth morphology. Our results establish fsTRS technique as the indispensible tool for the detection and characterization of complex ground states in nano-sized systems. Photoinduced reflectivity transients in a) bulk K0.3MoO3 and b) thin film of K0.3MoO3 on Al2O3 substrate as a function of temperature recorded at the same excitation density.

The dynamics of depletion and recovery of a superconducting state in La2-xSrxCuO4 thin films is investigated utilizing optical pump-probe and optical pump-THz-probe techniques as a function of temperature and excitation fluence. The absorbed energy density required to suppress superconductivity is found to be about eight times higher than the thermodynamically determined condensation energy density and nearly temperature independent between 4 and 25 K. These findings indicate that, during the time when the superconducting state suppression takes place (≈0.7 ps), a large part (nearly 90%) of the energy is transferred to the phonons with energy lower than twice the maximum value of the superconducting gap and only 10% is spent on Cooper pair breaking.

We present the first systematic studies of the photoinduced phase transition from the ground charge density wave (CDW) state to the normal metallic state in the prototype quasi-1D CDW system K0.3MoO3. Ultrafast nonthermal CDW melting is achieved at the absorbed energy density that corresponds to the electronic energy difference between the metallic and CDW states. The results imply that on the subpicosecond time scale when melting and subsequent initial recovery of the electronic order takes place the lattice remains unperturbed.

Here we report on detailed studies of the photoexcited carrier and collective mode dynamics in prototype quasi-1D charge density wave (CDW) systems K0:3MoO3 and Rb0:3MoO3 focusing on their low temperature and low excitation range. We show that the order parameter relaxation dynamics are inconsistent with the Rothwarf– Taylor model describing the relaxation of the coupled quasi-particle and high frequency phonon system in a system with a narrow gap in the density of states. Therefore we propose an alternative model that accounts for the photoexcited carrier relaxation phenomena commonly observed in CDW systems.