Two-Frequency waveguide CO2 laser for atmospheric pollution monitoring

The present paper suggests and discusses a method allowing one to produce a two-frequency switching mode between any two adjacent transitions of a CO₂ laser. Switching is achieved by means of simple modulation of the resonator length by a piezoelement. The use of conventional electronic circuits ensures the maintainance of a high power balance (10^–2–10^–1%) vs. switching rate) at the generation frequencies. The data of the two-frequency CO₂ laser with a waveguide resonator used for various systems, based on a differential absorption technique and designed to control the atmospheric pollutions, are presented.     

Fe/Cr and Cu/Cr film pressure-sensitive elements

A pressure-sensitive element based on Fe/Cr or Cu/Cr film composition is described. The role of interdiffusion and phase formation is discussed, and the interface stability is studied.     

Electrochemical synthesis and properties of iron–titanium dioxide composite coatings

Deposition of Fe/TiO₂ composite coatings from a colloidal methanesulfonate electrolyte containing titanium dioxide hydrosol was studied. The TiO₂ content in the composite increases with increasing the dispersed phase content and decreasing the current density. Incorporation of TiO₂ particles into the iron matrix resilts in an increase in the microhardness of the deposit. The electroplated Fe/TiO₂ composite coating was used as a heterogeneous photocatalyst for the decomposition of an organic dye under the action of UV radiation.     

Quantum theory of dipole nanolasers

We generalize the semiclassical model of the dipole nanolaser (DNL) based on the Heisenberg?CLangevin approach, taking into account spontaneous emission of plasmons into the generation mode, nonlinearity of generation, and noises. We find a ??thresholdless?? smooth transition from the spontaneous emission to the stimulated emission and the threshold conditions for such a transition and determine the spectrum of generation and its linewidth. We show that, in spite of the very low quality of the DNL generation mode, the linewidth of a DNL with many M ?? 10⁴ ? 10⁵ emitters decreases, with the pump increase, to quite small values ~ 10^?2 of the width 2??₂ of the lasing transition at modest pump rates, about 30 times larger that the decay rate of the emitter upper lasing state. This fact confirms the practical possibilities of realizing DNLs with narrow-line stimulated emission. Otherwise, the linewidth of DNLs with small M ?? 1 number of emitters is larger than 2??₂ and increases with the pump rate. In addition our results on DNLs can be applied to other lasers, such as nanolasers, microlasers, and LEDs for lighting, also with a low-quality cavity and strong spontaneous emission into the generation mode.