J. Appl. Cryst.の発刊に際して

Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).

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Lanthanide luminescence for functional materials and bio-sciences

Lanthanide-based luminescent hybrid materials.

Upconversion luminescent materials: advances and applications.

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

Integrated $Al_2O_3:Er^{3+}$ channel waveguide ring lasers were realized on thermally oxidized silicon substrates. High pump power coupling into and low laser output power coupling from the ring is achieved in a straightforward
design. Output powers of up to 9.5 $\mu $W and slope efficiencies of up to 0.11% were measured while lasing was observed for a threshold diode-pump power as low as 6.4 mW for ring lasers with cavity lengths varying from 2.0 to 5.5 cm. Wavelength selection in the range 1530–1557 nm was demonstrated by varying the length of the output coupler from the ring.

Integrated $Al_2O_3:Er^{3+}$ ring lasers on silicon with wide wavelength selectivity

Signal transmission experiments were performed at 170 Gbit/s in an integrated $Al_2O_3:Er^{3+}$ waveguide amplifier to investigate its potential application in high-speed photonic integrated circuits. Net internal gain of up to 11 dB was measured for a continuous-wave 1532 nm signal under 1480 nm pumping, with a threshold pump power of 4 mW. A differential group delay of 2 ps between the TE and TM fundamental modes of the 5.7-cm-long amplifier was measured. When selecting a single polarization open eye diagrams and bit error rates equal to those of the transmission system without the amplifier were observed for a 1550 nm signal encoded with a 170 Gbit/s return-to-zero pseudo-random $2^{7}-1$ bit sequence.

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170 Gbit/s transmission in an erbium-doped waveguide amplifier on silicon.

Epitaxially grown, 2.4-μm-thin layers of KY(WO4)2:Gd3+, Lu3+, Yb3+, which exhibit a high refractive index contrast with respect to the undoped KY(WO4)2 substrate, have been microstructured by Ar beam milling, providing 1.4-μm-deep ridge channel waveguides of 2 to 7 μm width, and overgrown by an undoped KY(WO4)2 layer. Channel waveguide laser operation was achieved with a launched pump power threshold of only 5 mW, a slope efficiency of 62% versus launched pump power, and 76 mW output power.

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Microstructured KY(WO 4 ) 2 :Gd 3+ , Lu 3+ , Yb 3+ channel waveguide laser

An integrated arrayed-waveguide grating fabricated in silicon-oxynitride technology is applied to Raman spectroscopy. After its validation by reproducing the well-known spectrum of cyclohexane, polarized Raman spectra are measured of extracted human teeth containing localized initial carious lesions. Excellent agreement is obtained between the spectra of healthy and carious tooth enamel measured with our integrated device and spectra recorded using a conventional Raman spectrometer. Our results represent a step toward the realization of compact, hand-held, integrated spectrometers, e.g. for the detection of dental caries at an early stage.

Raman spectroscopy with an integrated arrayed-waveguide grating

High-quality crystalline $KY(WO_4)_2:Yb^{3+}$ layers codoped with large concentrations of optically inert Gd3+ and Lu3+ ions were grown by liquid phase epitaxy. Continuous-wave laser operation in a planar waveguide configuration was observed at 1025 nm. For 23% output coupling, a maximum output power of 195 mW was obtained; a slope efficiency of 82.3% was derived, which to the best of our knowledge is the highest value yet reported for a planar waveguide laser to date. For 1.7% output coupling, a laser threshold as low as 18 mW of absorbed pump power was achieved, which is largely due to the enhanced refractive index contrast of ~$7.5\times 10^{-3}$ between the active layer and the undoped $KY(WO_4)_2$ substrate attained by the co-doping, leading to well-confined pump and laser modes

Kerstin Worhoff

Papers

Integrated $Al_2O_3:Er^{3+}$ ring lasers on silicon with wide wavelength selectivity

170 Gbit/s transmission in an erbium-doped waveguide amplifier on silicon.

Microstructured KY(WO 4 ) 2 :Gd 3+ , Lu 3+ , Yb 3+ channel waveguide laser

Raman spectroscopy with an integrated arrayed-waveguide grating

Low-threshold, highly efficient Gd3+, Lu3+ co-doped KY(WO4)2:Yb3+ planar waveguide lasers