Ryszard Piramidowicz

Spectroscopy and upconversion processes in YAlO3:Ho3+ crystals

Abstract Emission from the high lying excited states, energy transfer, and upconversion processes are investigated in YAlO 3 :Ho 3+ . Selectively excited emission spectra in the range from 300 to 800 nm starting from the 3 D 3 , 3 G 5 , 5 F 3 , 5 S 2 and 5 F 5 multiplets were measured at 15 K. This, together with the detailed absorption and excitation measurements at 15 K allowed determination of the Stark energy levels of Ho 3+ ions in YAlO 3 up to UV energies. The 5 S 2 fluorescence decays were recorded as a function of temperature and Ho 3+ concentration in order to investigate the process of quenching of fluorescence due to cross relaxation among two ions. Conversion of red and infrared laser radiation to green 5 S 2 and blue 5 F 3 emission is reported. Under pulsed resonant excitation of the 5 F 5 or 5 I 5 levels the upconversion was found to be due to energy transfer process between two excited ions. The photon avalanche effect was observed under cw excitation around 585 nm.

InP-Based Photonic Multiwavelength Transmitter With DBR Laser Array

We demonstrate an InP-based photonic multiwavelength transmitter realized by integrating an array of distributed Bragg reflector lasers with modulators in Mach-Zehnder configuration. An arrayed waveguide grating is used to multiplex the generated signals into a common optical output. The device is designed according to a generic integration concept, using standardized building blocks, and is fabricated in a multiproject wafer run. The device delivers up to 4 dBm of optical power into the fiber with a modulation data rate of 12.5 Gbps per transmission channel. The obtained performance makes it very promising for application in the next generation optical access networks as a key source in the central office part of the telecommunication systems.

Spectroscopy of Dy3+-doped SrLaGa3O7 crystals

We report the optical properties of SrLaGa3O7 (SLG) crystal doped with Dy3+ ions. Absorption, emission, excitation and lifetime measurements have been performed and discussed using Judd-Ofelt theory. Visible emission spectra from the 4F92 level and infrared (1.35 μm) spectra from the 6H92 level of Dy3+ in SLG have been studied and the experimental lifetimes of these levels have been compared to the radiative, calculated lifetimes. Finally, emission properties of Dy3+ are being compared with those of Pr3+ ion.

Blue-green emission of Pr3+ ions in LiNbO3

The emission properties of the 3 P0 state of praseodymium ions in lithium niobate crystal have been studied. Blue-green emission at 510 nm corresponding to the 3 P0 3 H4 transition in Pr3+ :LiNbO3 crystals was generated after direct and up-conversion excitation with orange and infrared radiation around 920 nm. The up-conversion mechanisms were shown to be energy transfer and excited state absorption for orange and infrared excitation, respectively. The processes responsible for non-radiative relaxation of the 3 P0 state were also determined.

Optical transitions of Pr3+ ions in Ca4GdO(BO3)3 crystals

Abstract Optical properties of Pr 3+ ions in gadolinium calcium oxoborate Ca 4 GdO(BO 3 ) 3 (GdCOB) nonlinear crystals have been studied. Polarized absorption and emission spectra and fluorescence lifetime measurements have been performed and discussed using modified Judd-Ofelt theory. The system is characterized by intense red emission at 610 nm corresponding to the 1 D 2 → 3 H 4 transition, no emission from the excited 3 P 0 state has been observed. 1 D 2 emission has been investigated under pulsed excitation and the experimental lifetimes for this level has been compared with this obtained theoretically by using Judd–Ofelt approach.

Infrared-to-blue-wavelength upconversion in thin film grown by liquid phase epitaxy

Blue emission at 486 nm corresponding to the transition in (GGG) thin epitaxial film was generated after excitation with infra-red radiation at around 890 nm. The upconversion mechanism was shown to be excited-state absorption from the multiplet. The spectroscopic properties of the state of in GGG were also studied. The emission spectra of bulk crystals and thin film are centred at , and the measured lifetime is about at room temperature. Blue-wavelength upconversion excitation spectra and direct infra-red excitation spectra allowed us to determine the Stark energy levels in the and multiplets.

Luminescent properties of praseodymium doped Y2O3 and LaAlO3 nanocrystallites and polymer composites

Abstract Luminescent properties of Y2O3 and LaAlO3 nanopowders doped with Pr3+ ions and PMMA-based composite materials doped with these powders were reported. The set of active nanopowders differing in praseodymium ions concentration was prepared using sol-gel method and carefully characterized with respect to emission properties in the visible spectral range. In particular, the excitation and emission spectra were measured together with fluorescence decay profiles and the differences between optical properties of these materials were discussed and compared with data available for bulk materials. Finally, the PMMA-based composite materials doped with Pr3+:Y2O3 and Pr3+:LaAlO3 nanopowders were manufactured and characterized. The obtained results showed that polymer composites doped with active nanopowders in general tended to keep the luminescent properties of the original nanopowders.

Monolithically integrated 8-channel WDM reflective modulator

In this work the design and characterization of a monolithically integrated photonic circuit acting as a reflective modulator for eight WDM channels is presented. The chip was designed and fabricated in a generic integration technology.

Luminescent properties of polymer nanocomposites activated with praseodymium-doped nanocrystals

In this work we report the recent results of our investigation on visible emission properties of the polymer nanocomposites doped with oxide and fluoride nanopowders activated with praseodymium ions. The set of LaAlO3 and YF3 nanopowders differing in active ions concentration, was carefully characterized with respect of their structural and luminescent properties. Also the PMMA-based nanocomposites doped with these nanopowders were manufactured and characterized. The measurements of excitation and emission spectra as well as fluorescence decays enabled comparison of emission properties of nano-composites and original nanopowders and discussion of the main excitation and deexcitation mechanisms, responsible for the optical properties of developed materials. This, in turn will enable optimization of developed manufacturing technology.

Dynamics of the Up-Conversion Emission in Holmium Doped Zblan Fiber

The dynamics of up-conversion, green emission under excitation at different infra-red wavelength in Ho3☎ doped ZBLAN fiber is reported. Under infrared, 890 nm quasi cw pumping the complicated temporal behavior of the up-conversion signal is strongly influenced by the intermediate 5I5 state cross relaxation. The mechanisms of the observed up-conversion processes are proposed and the time evolution of the 5S2 population is described by the rate equation model. Parameters of the model are determined and numerical simulations of the excited state dynamics are performed.