Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy. Photonic ADCs, which perform sampling using ultra-stable optical pulse trains generated by mode-locked lasers, have been investigated for many years as a promising approach to overcome the jitter problem and bring ADC performance to new levels. This work demonstrates that the photonic approach can deliver on its promise by digitizing a 41 GHz signal with 7.0 effective bits using a photonic ADC built from discrete components. This accuracy corresponds to a timing jitter of 15 fs -a 4-5 times improvement over the performance of the best electronic ADCs which exist today. On the way towards an integrated photonic ADC, a silicon photonic chip with core photonic components was fabricated and used to digitize a 10 GHz signal with 3.5 effective bits. In these experiments, two wavelength channels were implemented, providing the overall sampling rate of 2.1 GSa/s. To show that photonic ADCs with larger channel counts are possible, a dual 20-channel silicon filter bank has been demonstrated. 289-296 (1992). 11. J. Kim, J. Chen, J. Cox, and F. X. Kärtner, "Attosecond-resolution timing jitter characterization of free-running mode-locked lasers using balanced optical cross-correlation," Opt. Lett. microwave signals at 40-GHz with higher than 7-ENOB resolution," Opt. ©2012 Optical Society of America

Entirely transparent pixels composed of monolithically integrated transparent organic light‐emitting diodes driven by transparent thin‐film transistors are presented. With an average transmittance of more than 70 % (see figure and inside cover) in the visible part of the spectrum (400–750 nm), the presented active pixels pave the way to the realization of fully transparent active‐matrix displays. Low processing temperatures mean that flexible transparent displays may be feasible.

We demonstrate a high-repetition-rate soliton fiber laser that is based on highly doped anomalously dispersive erbium-doped fiber. By splicing an 11 mm single-mode fiber to the erbium-doped fiber, the thermal damage of the butt-coupled saturable Bragg reflector (SBR) is overcome. The laser generates 187 fs pulses at a repetition rate of 967 MHz with a measured long-term stability of more than 60 h.

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