André Richter

Diode pumping of a continuous-wave Pr 3+ -doped LiYF 4 laser

We report, for the first time to our knowledge, diode-pumped cw laser oscillation of Pr3+:LiYF4 in the red spectral range. The pump power is provided by a GaN laser diode emitting a maximum output power of 25 mW at a wavelength of approximately 442 nm. The Pr3+ laser emits 1.8 mW of output power at a 639.7-nm wavelength. Threshold pump power and slope efficiency in a nonoptimized setup are determined to be 5.5 mW and 24%, respectively.

Power scaling of semiconductor laser pumped Praseodymium-lasers

We report on efficient lasing of Pr-doped fluoride materials with cw output powers up to 600 mW in the visible spectral range. Praseodymium doped LiYF(4) and LiLuF(4) crystals were pumped either by an intracavity frequency doubled optically pumped semiconductor laser with output powers up to 1.6 W and nearly diffraction limited beam quality or by a multimode GaN-laser diode with an output power of about 370 mW. Furthermore, intracavity frequency doubling of the red Pr-laser radiation to 320 nm reaching output powers of more than 360 mW with a conversion efficiency of 61% and an optical-to-optical efficiency of 22% are presented.

Efficient visible laser emission of GaN laser diode pumped Pr-doped fluoride scheelite crystals

In the present work we report on the growth, spectroscopy and laser results of diode pumped Pr-doped LiYF(4), LiLuF(4) and LiGdF(4) fluoride, scheelite-type structure crystals. We measured the polarisation dependent absorption and emission properties as well as the decay time of the (3)P(0) level. Exploiting the (3)P(2) absorption around 444 nm, we obtained efficient laser emission under GaN laser diode pumping on several transitions from the green to the near infrared wavelength range.

Visible laser emission of solid state pumped LiLuF(4):Pr(3+).

In this work we investigate visible transitions of Pr in the crystal Pr:LiLuF4. In particular we will report on the growth, emission and absorption spectroscopy as well as laser action at four different wavelengths. Findlay-Clay and Caird analysis have been carried out in order to characterise the cavity and the crystal quality. To the best of our knowledge the reported slope efficiencies are the highest reached for a Pr-based laser.

Multiple signal representation simulation of photonic devices, systems, and networks

Photonic systems design requires simulation over a wide range of scales; from wavelength-sized resonances in lasers and filters, to interactions in global networks. To design these global systems, while considering the effects of the smallest component, requires sophisticated simulation technology. We have developed the Photonic Transmission Design Suite, which includes five different signal representations, so that the details of device performance can be efficiently considered within a large network simulation. Alternatively, a design can be studied using a coarse signal representation before switching to a detailed representation for further refinement. We give examples of the application of these representations, and show how the representation of a signal is adapted as it propagates through a system to optimize simulation efficiency.

Continuous-wave ultraviolet generation at 320 nm by intracavity frequency doubling of red-emitting Praseodymium lasers

We describe a new approach for the generation of coherent ultraviolet radiation. Continuous-wave ultraviolet light at 320 nm has been obtained by intracavity frequency doubling of red-emitting Praseodymium lasers. Lasing at the 640-nm fundamental wavelength in Pr:LiYF(4) and Pr:BaY(2)F(8) was realized by employing an optically pumped semiconductor laser at 480 nm as pump source.Using LiB(3)O(5) as nonlinear medium, ~19 mW of ultraviolet radiation with ~9% optical efficiency with respect to absorbed power was reached for both laser crystals; the visible-to-ultraviolet conversion efficiency was 26% and 35% for Pr:LiYF(4) and Pr:BaY(2)F(8), respectively.

Improved DSP algorithms for coherent 16-QAM transmission

We propose new algorithms for adaptive mitigation of coherent 16-QAM constellation distortions. We show that 16-QAM is a potential candidate for the implementation of 100 Gb/s transmission.

Adaptive nonlinear Volterra equalizer for mitigation of chirp-induced distortions in cost effective IMDD OFDM systems

We report experimental validations of an adaptive 2nd order Volterra equalization scheme for cost effective IMDD OFDM systems. This equalization scheme was applied to both uplink and downlink transmission. Downlink settings were optimized for maximum bitrate where we achieved 34 Gb/s over 10 km of SSMF using an EML with 10 GHz bandwidth. For the uplink, maximum reach was optimized achieving 14 Gb/s using a low-cost DML with 2.5 GHz bandwidth.

Continuous wave Praseodymium solid-state lasers

We review spectroscopic properties, basic laser parameters, and efficient lasing of Pr-doped fluoride materials. Continuous output powers up to 600 mW in the visible spectral range as well as intracavity frequency doubling to the UV spectral region under semiconductor laser pumping is reported. We achieved powers of 600 mW in the visible spectral region and 360 mW of UV radiation corresponding to a conversion efficiency of 61% with an optical-to-optical efficiency of 22%.

Optimum dispersion mapping of single-channel 40 Gbit/s return-to-zero differential phase-shift keying transmission systems

We present a numerical study of the performance of 40 Gbit/s return-to-zero differential phase-shift keying (RZ-DPSK) transmission with different dispersion maps. The optimum dispersion mapping for RZ-DPSK format are discussed and compared with those for on-off keying (OOK). Two pseudo-linear transmission systems, one using standard single-mode fiber and the other nonzero dispersion-shifted fiber, are investigated, respectively. In principle, the optimum dispersion mapping for RZ-DPSK format is different from that for OOK and depends on intra-channel four-wave mixing and nonlinear phase noise.