Miroslaw Kwasny

Growth and optical properties of Nd:YVO4 laser crystals

Growth conditions for Nd:YVO4 crystals and some optical properties are presented. The obtained Nd:YVO4 crystal shows lower content of point defects and consequently, lower susceptibility to ionizing radiation. ESR measurements show the presence of V ions in interstitial sites with another than 5t valency. Obtained by Czochralski method crystals reveal very good optical properties, some of which are better than for Nd:YAG.

KGW:Yb, Er single crystals growth for eye-safe lasers

KGd(WO4)2 (KGW) single crystals doped with Yb3+, Er3+, and (Yb3+; Er3+) were grown with use of Top Seeded Solution Growth (TSSG) technique. Growth was carried out on oriented seeds from self-flux containing 20 mol% of KGW dissolved in K2W2O7. The spectral properties and laser characteristics of obtained single crystals were investigated. Absorption spectra of Er3+ and Yb3+-doped KGW were measured in the spectral range 200 ÷ 5000 nm at room temperature. Excitation and luminescence spectra were also recorded at room temperature with a JOBIN-YVON spectrofluorimeter using a diode laser (POLAROID 4300, 980 nm, 1 W) as an excitation source. The measurements of the lifetime of the Er3+ and Yb3+ ions in the upper laser level of the samples were made by the direct method with pulse excitation. Investigations of longitudinally pumped KGW:Yb,Er microlasers with various Yb3+ and Er3+ ions concentration, generating at 1.5 μm were carried out.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Excitation emission spectra of laser materials for UV-VIS range

Excitation-mission spectra have been measured for Pr3+, Ce3+, Nd3+ and Eu3+ doped YAP, YAG, and SLGO crystals in room temperature. Results of additional absorption measurements and changes in a luminescence after gamma irradiation with dose up to 105 Gy and energy of 2.5 MeV are also presented.

Gamma-induced effect of recharging: Ce4+--Ce3+ in Ce3+ and Nd3+ doped YAG crystals

Gamma-induced transition of Ce4+

Development of methane detection system

ARLR Ce3+ was investigated for Ce,Nd:YAG samples cut off from the same crystal and differing one to another by a few tenth percent of Ce3+ ions concentration (starting concentration). Depending on the starting concentration changes of resulting concentration of Ce3+ ions were observed. The luminescence of Ce,Nd:YAG crystal at about 530 nm increased independently on Ce3+ starting concentration.

Investigations of YAG:Er3+,Yb3+ and YAG:Co2+ crystals for laser application

The paper describes the design, development and examination of a prototype dual He-Ne IHe-Xe laser system for gas detection using differential absorption of radiation backscattered from topographic targets. Both lasers were excited by RF discharge. For lengths of 50 cm we obtained the output power of about 10 mW. Using receiver optics with the diameter of 7 cm and thermocooled HgCdTe detector the presence of methane on the distance up to 50m. can be measured. The new solution is under construction. To increase the range of measurement Casseigrain optics with diameter of 30 cm is being prepared. Using the special construction of gas lasers with the output power of 30 mW, the measurement distance of 200 m is expected.

Light sources currently used in photochemotherapy

The results of examinations of spectroscopic properties and generation parameters of new active media, i.e., Er3+ and Yb3+ doped YAG crystals are given. Erbium and ytterbium doped YAG single crystals were obtained by the Czochralski method. The spectral properties and laser characteristics were investigated. Absorption spectra of Er3+ and Yb3+-doped active media were measured in the spectral range 190 divided by 5000 nm at room temperature. Excitation and luminescence spectra were also recorded at room temperature with a JOBIN-YVON spectrofluorimeter using a diode laser as an excitation source. The measurements of the lifetime of the Er3+ ions in the upper laser level of the samples were made by the direct method with pulse excitation. We present also the result of investigations on spectroscopic properties and non-linear absorption effect in YAG:Co2+ crystal-new absorber used for the systems generating giant-pulse radiation at 1.5 micrometers .

Influence of proton irradiation on optical characteristics of LiNbO3:Cu wafers

The availability of low-cost therapeutic illuminators was one of the key factors to limit clinical use of PDT. The paper presents modern light sources which have revolutionized PDT method, contributing to its more common use. The technical parameters of different illuminators are compared. Finally, own light sources were presented and developed in Polish clinics.

Wideband antireflection coatings on germanium and filters for second optical window

Optical homogeneity (birefringence and birefringence dispersion mapping, transmission and additional absorption) was investigated on the entire areas of LiNbO3 wafers doped with Cu ions and irradiated with protons of fluencies ranging between 1012 and 1016 cm-2. The birefringence dispersion studies have revealed a considerable influence of protons on LiNbO3:Cu optical inhomogeneity, whereas the same influence on undoped LiNb03 was much less significant. The spectroscopic studies have revealed different mechanisms of defect formation depending on doses of protons. Also the secondary electrons generated by proton irradiation are believed to decrease the optical homogeneity by decreasing crystals conductivity and generation of the color centers.

Valency change of active and nonactive ions inside oxide single crystals applied in optoelectronic devices

The investigation results of wideband (8-12 μm) antireflection coatings on germanium substrate and spectral characteristics of interference wideband filter for spectral range of 8-12 μm are presented. For design of filters and antireflection coatings the following layer materials were used: Ge, ZnS and Mira, and substrate materials such as: Ge for antireflection coatings and ZnSe for interference filters. Wideband filter for the range of 8-12 μm requires application of additional two filters cutting off radiation from the range of 1-7 μm. The cutting off filters are interference filters for which construction germanium, Mira, and ZnS were used. The constructions of basic and cutting off filters were designed considering technical possibilities of vacuum device BAK 550 of the Balzers firm.