A Diode-Side-Pumped Dynamic Fundamental Mode Nd:YAG Laser

A fundamental mode Nd YAG laser is experimentally demonstrated with a stagger pumped laser module and a special resonator. The rod is pumped symmetrically by staggered bar modules. A dynamic fundamental mode is achieved with the special resonator under different pump levels. A maximal continuous wave output of 61 W (M-2 = 1.4) is achieved with a single rod. An average output of 47 W, pulse width of 54 ns, pulse energy of 4.7 mJ and peak power of 87 kW are obtained under the Q-switched operation of 10 kHz.

Phase-separation suppression in GaN-rich side of GaNP alloys grown by metal-organic chemical vapor deposition

The GaN-rich side of GaNP ternary alloys has been successfully synthesized by light-radiation heating and low-pressure metal-organic chemical vapor deposition. X-ray diffraction (XRD) rocking curves show that the ( 0002) peak of GaNP shifts to a smaller angle with increasing P content. From the GaNP photoluminescence (PL) spectra, the red shifts from the band-edge emission of GaN are determined to be 73, 78 and 100 meV, respectively, in the GaNP alloys with the P contents of 1.5%, 5.5% and 7.5%. No PL peak or XRD peak related to GaP is observed, indicating that phase separation induced by the short-range distribution of GaP-rich regions in the GaNP layer has been effectively suppressed. The phase-separation suppression in the GaNP layer is associated with the high growth rate and the quick cooling rate under the given growth conditions, which can efficiently restrain the accumulation of P atoms in the GaNP layer.

Mode characteristics of semiconductor equilateral triangle microcavities with side length of 5-20 mu m

Semiconductor equilateral triangle microresonators (ETRs) with side length of 5, 10, and 20 mum are fabricated by the two-step inductively coupled plasma (ICP) etching technique. The mode properties of fabricated InGaAsP ETRs are investigated experimentally by photoluminescence (PL) with the pumping source of a 980-nm semiconductor laser and distinct peaks are observed in the measured PL spectra. The wavelength spacings of the distinct peaks agree very well with the theoretical longitudinal mode intervals of the fundamental transverse modes in the ETRs, which verifies that the distinct peaks are corresponding to the enhancement of resonant modes. The mode quality factors are calculated from the width of the resonant peaks of the PL spectra, which are about 100 for the ETR with side length of 20 mum.

Side radical influence on the nonlinear optical properties and thermal stability of poled polymer films

Films of polyetherketone doped with the chromophores Disperse Red 1 (DR1) and Disperse Red 13 (DR13) were prepared by spin-coating method. By the in situ Second-harmonic Generation (SHG) signal intensity measurement, the optimal poling temperatures were obtained. For the investigated polyetherketone polymer doped with DR1 (DR1/PEK-c) and polyetherketone polymer doped with DR13 (DR13/PEK-c) films, the optimal poling temperatures were 150degreesC and 140degreesC, respectively. Under the optimal poling conditions, the high second-order nonlinear optical coefficient chi(33)((2)) = 11.02 pm/V has been obtained for the DR1/PEK-c; and for DR13/PEK-c at the same conditions the coefficient is 17.9 pm/V. The SHG signal intensity DR1/PEK-c could maintain more than 80% of its initial value when the temperature was under 100degreesC, and the SHG signal intensity of the DR13/PEK-c could maintain more than 80% of its initial value when the temperature was under 135degreesC. (C) 2002 Kluwer Academic Publishers.

Assembly of side-functional monomers with inorganic nanometer particles

Monomers of methacrylate with various pi -conjugated pendants were designed and prepared in our laboratory, The monomer with suitable end-group was successfully assembled with nano-scale inorganic particles to form an orderly-aligned structure that showed special optical properties, both absorption and emission band were much red-shifted compared with the monomer, A new type of organic/inorganic hybrid materials was obtained by in situ polymerization of the assembly, The hybrid materials could also show special optical properties as the assembly, This might open a new route to tune the emission color.

Photoluminescence study of InxGa1-xAs/InyAl1-yAs one-side-modulation-doped asymmetric step quantum wells

Fourier transform photoluminescence measurements were carried out to investigate the optical transitions in InxGa1-xAs/InyAl1-yAs one-side-modulation-doped asymmetric step quantum wells. Samples with electron density n(s) between 0.8 and 5.3 x 10(12) cm(-2) rue studied. Strong recombination involving one to three populated electron subbands with the first heavy-hole subband is observed. Fermi edge singularity (FES) clearly can be observed for some samples. The electron subband energies in the InGaAs/InAlAs step quantum wells were calculated by a self-consistent method, taking into account strain and nonparabolicity effects and the comparison with the experimental data shows a good agreement. Our results can help improve understanding for the application of InGaAs/InAlAs step quantum wells in microelectronic and optoelectronic devices. (C) 1998 Elsevier Science Ltd. All rights reserved.

Design considerations for a silicon-based p-i-n phase modulator in a double ridge waveguide with side isolating grooves

We present detail design considerations and simulation results of a forward biased carrier injection p-i-n modulator integrated on SOI rib waveguides. To minimize the free carrier absorption loss while keeping the comparatively small lateral dimensions of the modulator as required for high speed operation, we proposed two structural improvements, namely the double ridge (terrace ridge) structure and the isolating grooves at both sides of the double ridge. With improved carrier injection and optical confinement structure, the simulated modulator response time is in sub-ns range and absorption loss is minimized.

A New Technique for Side Pumping of Double-Clad Fiber Lasers

We report a new technique, called SAP, for side pumping of double-clad, rare-earth-doped fiber lasers using fiber-coupled pump sources. The highest coupling efficiency can even exceed 92% in theory with this structure.

LD side-pumped high beam quality passive Q-switched and mode-locked Nd:YAG laser based on SESAM

We report a LD side-pumped fundamental-mode (Mx(2) = 1.35 and My(2) = 1.27) passive Q-switched and mode-locked Nd:YAG laser based on a semiconductor saturable absorber mirror (SESAM). At a pump current of 12.5 A, the average output power of 5.68 W with 80 kHz repetition rate and 2 mu s pulse width of the Q-switched envelope was generated. The repetition rate of the mode-locked pulse within the Q-switched envelope of 88 MHz was achieved.

Sol-gel matrix modified microstructured optical fibre towards a fluoride sensitive optical probe

In this article, we report an optical fluoride probe based on microstructured polymer optical fibers (MPOFs) which is modified with morin-Al complex doped silica gel film. This probe is fabricated by sol-gel fluxion coating process. Sol solution doped with morin-Al is directly inhaled into array holes of MPOF and then forms morin-Al-gel matrix film in them. The sensing probe shows different fluorescence intensity to different fluoride ion concentrations in the aqueous solution. The range of response is 550 mmol/L, under the condition of pH 4.6. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.

A linkage map of common carp (Cyprinus carpio) based on AFLP and microsatellite markers

P>Common carp (Cyprinus carpio) is an important fish for aquaculture, but genomics of this species is still in its infancy. In this study, a linkage map of common carp based on Amplified Fragment Length Polymorphism (AFLP) and microsatellite (SSR) markers has been generated using gynogenetic haploids. Of 926 markers genotyped, 151 (149 AFLPs, two SSRs) were distorted and eliminated from the linkage analyses. A total of 699 AFLP and 20 microsatellite (SSR) markers were assigned to the map, which comprised 64 linkage groups and covered 5506.9 cM Kosambi, with an average interval distance of 7.66 cM Kosambi. The normality tests on interval map distances showed a non-normal marker distribution. Visual inspection of the map distance distribution histogram showed a cluster of interval map distances on the left side of the chart, which suggested the occurrence of AFLP marker clusters. On the other hand, the lack of an obvious cluster on the right side showed that there were a few big gaps which need more markers to bridge. The correlation analysis showed a highly significant relatedness between the length of linkage group and the number of markers, indicating that the AFLP markers in this map were randomly distributed among different linkage groups. This study is helpful for research into the common carp genome and for further studies of genetics and marker-assisted breeding in this species.

IMPROVEMENT OF STRUCTURAL INSTABILITY OF THE ION-SENSITIVE FIELD-EFFECT TRANSISTOR (ISFET)

Three causes involved in the instability of the ISFET are proposed in this study. First, it is ascertained that hydroxyl group resident at the surface of the Si3N4 film or in the electrolyte solution is most active and subject to gain or loss of electrons. This is one of the main causes for ISFET structural instability. Secondly, the stability of the pH-sensitive FET varies with deposition conditions in the fabrication process of the ISFET. This proves to be another cause of ISFET instability. Thirdly, the pH of the measured solution varies with the measuring process and time, contributing to the instability, but is not a cause of the instability of the pH-ISFET itself. We utilized the technique of readjusting and controlling the ratio of hydroxyl groups to amine groups to enhance the stability of the ISFET. Our techniques to improve stability characteristics proved to be effective in practice.

EFFECT OF TOTAL HYDROGEN CONTENT IN SILICON-NITRIDE SENSITIVE FILM ON PERFORMANCE OF ISFET

Quantitative determinations of the hydrogen content and its profile in silicon nitride sensitive films by the method of resonant nuclear reaction have been carried out. At a deposition temperature of 825-degrees-C, hydrogen exists in an LPCVD silicon nitride sensitive film and the hydrogen content on its surface is in the range (8-16) x 10(21) cm-3, depending on the different deposition processes used. This hydrogen content is larger than the (2-3) x 10(21) cm-3 in its interior part, which is homogeneous. Meanwhile, we observe separate peaks for the chemical bonding configurations of Si-H and N-H bonds, indicated by the infrared absorption bands Si-O (1106 cm-1), N-H (1200 cm-1), Si-H-3 (2258 cm-1) and N-H-2 (3349 cm-1), respectively. The worse linear range of the ISFET is caused by the presence of oxygen on the surface of the silicon nitride sensitive film. The existence of chemical bonding configurations of Si-H, N-H and N-Si on its surfaces is favourable for its pH response.

Design,Fabrication,and Testing of Single-Side Alignment of 16×0.8nm Arrayed-Waveguide Grating

A novel design of 100GHz-spaced 16channel arrayed-waveguide grating (AWG) based on silica-on-silicon chip is reported.AWG is achieved by adding a Y-branch to the AWG and arranging the input/output channel in a neat row,so the whole configuration can be aligned and packaged using only one fiber-array.This configuration can decrease the device's size,enlarge the minimum radius of curvature,save time on polishing and alignment,and reduce the chip's fabrication cost.