V V Bezotosnyi

Application of diode lasers in light-oxygen cancer therapy

Singlet oxygen is the lowest energy electronic excited state of the oxygen molecule which is able to damage living cells. This property has long been used for the sensitized destruction of tumors in photodynamic cancer therapy. Here it is shown that similar results can be achieved without photosensitizers by using the light-oxygen effect. High-power continuous-wave (cw) diode lasers emitting within the absorption bands of dissolved molecular oxygen are most appropriate for light-oxygen cancer therapy.

Two-frequency lasing in the Nd:YLF laser with a lens-shaped active element and longitudinal diode pumping

In the laser with lens-shaped Nd:YLF [100] active element, the dependence of polarization and frequency of the radiation on the cavity length is studied under conditions of longitudinal diode pumping. The conditions at which birefringence in the Nd:YLF active element allows two-frequency lasing are determined.

Spectral features and thermal resistance of 976-nm cw laser diodes with a power up to 15 W

The spectral characteristics of cw laser diodes with a maximum reliable power of 15 W mounted on F-mount heat sinks are studied. It is found that the spectrum envelopes have features at emission powers exceeding 5 – 7 W. A method for determining the maximum of a spectrum envelope under the conditions of its broadening and appearance of features is discussed. The thermal resistance of diodes is determined experimentally at pump currents from threshold to maximum (14 A) and is found to be 2.25 K W-1 at a current of 10 A and 1.5 K W-1 at a current of 4 A. The results obtained are compared with the literature data. The adequacy of using the thermal resistance parameter for comparing and estimating thermal characteristics of laser diodes is considered.

Limiting parameters of high-power single-stripe laser diodes in the range of 800–808 nm in the pulsed mode

Experimental results on the study of the output parameters of high-power continuous-wave (cw) laser diodes operating in the pulsed mode and the results of numerical simulation of the total efficiency of laser diodes with cavity lengths of 3 and 4 mm in a wide range of pump currents are presented. The spectral parameters of the high-power laser diodes are studied at various pulse-repetition rates. The possible causes of the limited output power in the pulsed mode are discussed.

Lasing threshold of Nd-doped crystal, ceramic, and glass lasers under spatially inhomogeneous diode pumping

The effect of transverse mode locking on the dependence of the threshold pump power on the cavity length in Nd-doped media lasers with longitudinal inhomogeneous diode pumping is experimentally and theoretically studied in the cavity stability region. An essentially nonmonotonic behavior of the dependence of the threshold pump power on the cavity length is detected. The dependences of the threshold pump power on the cavity length are calculated using the method based on the expansion of the complex field amplitude in Laguerre-Gaussian modes of a cold cavity. The best agreement with calculated results is observed for lasers with Nd:YLF active elements.

Dual-wavelength generation at the transverse mode locking in a diode-end-pumped passively Q-switched Nd:YLF/Cr4+:YAG laser

A dual-wavelength generation at 1047 and 1053 nm is implemented in a diode-endpumped Nd:YLF laser Q-switched by Cr:YAG. This generation is obtained by the tuning of the cavity length near the regions of the transverse-mode degeneracy.

The peculiarities of spectra in high power 970 laser diodes

We present the results of optical power, total efficiency and spectra of CW laser diodes emitting at wavelength 970 nm. Total efficiency in maximum 72% was measured and reliable operation at 15 W CW was achieved. At the base of measured CW spectral parameters in wide range of pump currents we discuss the possible reasons of observed features in dependences of spectral envelope, spectral maximum and spectral half-width against pumping current.

Transverse mode locking of Stokes radiation in diode end-pumped Nd:YVO4 laser passively Q-switched by Cr4+:YAG

Transverse mode locking of the Stokes component generated in the mode of stimulated Raman scattering self-conversion by a pulsed diode end-pumped Nd:YVO4/Cr:YAG laser is implemented for the first time under conditions of frequency degeneracy of cavity modes.

60-W continuous wave laser diode arrays emitting at a wavelength of 808 nm

Samples of cw laser diode arrays (LDAs) with an output power higher than 60 W emitting in the spectral range of 808 nm are developed and fabricated. Main output parameters, including light–current, current–voltage characteristics, and emission spectra of a lot of 5 LDAs are measured.

Thermal Condition of High-Power Laser Diodes

Light-current and current-voltage characteristics of a set of high-power laser diodes of the spectral region of 980 nm, fabricated by the authors, are experimentally studied. The dependences of their total efficiency and heat load on the pump current are constructed. The latter experimental dependence is used for calculations in the three-dimensional thermal model of the laser diode with a stripe contact width of 100 µm. Thermal fields are studied and isothermal surfaces are constructed for laser diodes fabricated on C-mount heat sink elements under heat loads corresponding to output powers of 10 W and higher in continuous mode.