Narrow-Linewidth Distributed Feedback Channel Waveguide Laser in Al2_2O3_3:Er3+^{3+}

We report on the fabrication and characterization of a distributed feedback channel waveguide laser in erbium-doped aluminium oxide on a standard thermally oxidized silicon substrate. Holographically-written surface-relief Bragg gratings have been integrated with the aluminium oxide waveguides via reactive ion etching of a silicon dioxide overlay film. The laser operates at a wavelength of 1545.2 nm and exhibits a threshold of 2.2 mW absorbed pump power, while it produces a maximum output power of 3 mW. The emission is TE polarized and has a Lorentzian linewidth of 1.70±0.58 kHz, which corresponds to a Q-factor of 1.14×E11

High-Q distributed-Bragg-grating laser cavities

Applying Bragg gratings in Al2O3 channel waveguides, we demonstrate distributed Bragg reflectors with Q-factors of 1.02x10e6. An integrated Al2O3:Yb3+ waveguide laser with 67% slope efficiency and 47 mW output power is achieved with such cavities

Single-Frequency, Narrow-Linewidth Distributed Feedback Waveguide Laser in Al2O3:Er3+ on Silicon

A distributed feedback channel waveguide laser in erbium-doped aluminum oxide on a silicon substrate is reported. The optically pumped laser has a threshold pump power of 15 mW and emits 3 mW in single-frequency operation at 1545.2 nm wavelength with a slope efficiency of 6.2% and linewidth of 15 kHz

On-chip integrated amplifiers and lasers utilizing rare-earth-ion activation

This contribution reviews our recent results on rare-earth-ion-doped integrated amplifiers and lasers. We have concentrated our efforts on complex-doped polymers, amorphous Al2O3, and crystalline potassium double tungstates

Integrated Al2O3:Er3+ microring and distributed feedback lasers on silicon

Integrated rare-earth-ion-doped dielectric lasers have found\ud numerous applications in the medical, scientific, military and industrial fields, thanks to their high stability, low noise, narrow linewidth emission and broad wavelength tunability. Its favorable optical properties and compatibility with existing silicon waveguide technology make rare-earth-ion-doped aluminum oxide (Al2O3) a very promising gain medium to realize such integrated lasers.\ud Al2O3:Er3+ waveguide lasers are of interest due to their emission near 1.55 μm in the telecommunication C-band. The fabrication of low-loss Al2O3:Er3+ waveguides and internal optical gain over an 80-nm wavelength range with a peak gain of 2.0 dB/cm enabled the realization of various integrated Al2O3:Er3+ lasers on standard thermally oxidized silicon substrates. We report on the fabrication and performance of optically pumped channel waveguide ring and distributed feedback (DFB) lasers in Al2O3:Er3+. The low threshold ring-cavity lasers provide laser wavelength selection in the range 1530–1557 nm when varying the length of the output coupler from the ring. The DFB lasers exhibit output powers of more than 3 mW with slope efficiencies as high as 6.2% in single-frequency operation at 1545.2 nm with\ud linewidths below 15 kHz. These performance data illustrate the significance of Al2O3:Er3+ as a laser gain medium in dense wavelength division multiplexing in telecommunication networks

The regulatory mechanisms of NG2/CSPG4 expression

Neuron-glial antigen 2 (NG2), also known as chondroitin sulphate proteoglycan 4 (CSPG4), is a surface type I transmembrane core proteoglycan that is crucially involved in cell survival, migration and angiogenesis. NG2 is frequently used as a marker for the identification and characterization of certain cell types, but little is known about the mechanisms regulating its expression. In this review, we provide evidence that the regulation of NG2 expression underlies inflammation and hypoxia and is mediated by methyltransferases, transcription factors, including Sp1, paired box (Pax) 3 and Egr-1, and the microRNA miR129-2. These regulatory factors crucially determine NG2-mediated cellular processes such as glial scar formation in the central nervous system (CNS) or tumor growth and metastasis. Therefore, they are potential targets for the establishment of novel NG2-based therapeutic strategies in the treatment of CNS injuries, cancer and other conditions of these types