We present a novel approach for the simultaneous determination of the thermal conductivity κ and the total interface conductance g of supported 2D materials by the enhanced opto-thermal method. We harness the property of the Gaussian laser beam that acts as a heat source, whose size can easily and precisely be controlled. The experimental data for multi-layer graphene and MoS2 flakes are supplemented using numerical simulations of the heat distribution in the Si/SiO2/2D material system. The procedure of κ and g extraction is tested in a statistical approach, demonstrating the high accuracy and repeatability of our method.

In this work, we demonstrate a comprehensive study on the nonlinear parameters of carbon nanotube (CNT) saturable absorbers (SA) as a function of the nanotube film thickness. We have fabricated a set of four saturable absorbers with different CNT thickness, ranging from 50 to 200 nm. The CNTs were fabricated via a vacuum filtration technique and deposited on fiber connector end facets. Each SA was characterized in terms of nonlinear transmittance (i.e. optical modulation depth) and tested in a Thulium-doped fiber laser. We show, that increasing the thickness of the CNT layer significantly increases the modulation depth (up to 17.3% with 200 nm thick layer), which strongly influences the central wavelength of the laser, but moderately affects the pulse duration. It means, that choosing the SA with defined CNT thickness might be an efficient method for wavelength-tuning of the laser, without degrading the pulse duration. In our setup, the best performance in terms of bandwidth and pulse duration (8.5 nm and 501 fs, respectively) were obtained with 100 nm thick CNT layer. This is also, to our knowledge, the first demonstration of a fully polarization-maintaining mode-locked Tm-doped laser based on CNT saturable absorber.

We report a model for the description of a room temperature photocurrent temporal response in devices made of a chemical vapor deposition grown molybdenum disulfide monolayer. The proposed model distinguishes three components of a photoresponse that may be attributed to photoconductance and a photogating effect, where photogating involves environmental and intrinsic material contribution. We showed that each time constant obtained from the model differed by an order of magnitude and remained unaffected by changes of the environment, whereas the amplitudes behaved according to the attributed effects. Notably, the rising photocurrent signal was a useful source of information regarding the persistent photoconductivity effect. Finally, we demonstrated the versatility of our model by applying it to some previous reports on time-resolved photocurrent. Our results help to determine the optoelectronic properties of MoS 2 monolayers and future photosensitive devices operating at ambient room temperature.

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