Contact electrode method for bulk periodically poled LiNbO₃

Over the past few years, there has been increasing interest in the use of quasi-phase-matched (QPM) nonlinear crystals, which permit noncritical-phase-matching for any wavelengths in the transparency range of the crystal, and have the advantage of using the largest component of the nonlinear susceptibility tensor, one that is not available in birefringent phase matching without walk-off problems. QPM can be achieved by an appropriate periodic modulation of the nonlinear coefficient, which corresponds to periodic domain reversal in ferroelectric materials. In particular, the application of QPM to bulk nonlinear optics has been revolutionised by the emergence of electric field poling techniques for patterning the domain structure of ferroelectric and polar crystals. In all the reported fabrication processes the periodic electrode (consisting of resist and/or metal layers) has been fabricated on the surface of the crystal substrates by conventional photolithography.We report here a new fabrication process for PPLN - the contact electrode method (CEM) - in which the periodic electrode is pressed onto one of the substrate surfaces with a uniform electrode on the other. CEM does not need any photolithographic processes on the substrate surface which may lead to greatly reduced fabrication cost. Furthermore, CEM would be applicable for fabrications of periodically poled glass fiber

Distressed Relationships: Lessons from the Norwegian Banking Crisis

This paper measures the economy-wide impact of bank distress on the loss of relationship benefits. We use the near-collapse of the Norwegian banking system during the period 1988 to 1991 to measure the impact of bank distress announcements on the stock prices of firms maintaining a relationship with a distressed bank. We find that although banks experience large and permanent downward revisions in their equity value during the event period, firms maintaining relationships with these banks face only small and temporary changes, on average, in stock price. In other words, the aggregate impact of bank distress on the real economy appears small. We analyze the cross-sectional variation in firm abnormal returns and find that firms that maintain international bank relationships suffer more upon announcement of bank distress.bank relationship;bank distress;Norwegian banking crisis

The Impact of Bank Consolidation on Commercial Borrower Welfare

We estimate the impact of bank merger announcements on borrowers' stock prices for publicly-traded Norwegian firms.In addition, we analyze how bank mergers influence borrower relationship termination behavior and relate the propensity to terminate to borrower abnormal returns.We obtain four main results.First, on average borrowers lose about one percent in equity value when their bank is announced as a merger target.Small borrowers of target banks are especially hurt in large bank mergers, where they lose an average of about three percent.Second, bank mergers lead to higher relationship exit rates for three years after a bank merger, and small bank mergers lead to larger increases in exit rates than large mergers.Third, target borrower abnormal returns are positively related to pre-merger exit rates, indicating that firms that find it easier to switch banks are less harmed when their bank merges.Fourth, we find weak evidence that target borrowers with large merger-induced increases in exit rates are more negatively affected by bank merger announcements, suggesting that target borrowers are forced out of relationships and suffer welfare losses as a result of bank mergers.banks;mergers;bank lending

Optimization of plasmon–plasmon coupling in photorefractive layered media

In this paper we study grating-induced plasmon–plasmon coupling in photorefractive layered media using a weakcoupling approximation. The method used is applicable to general layered structures that support both plasmonic and optical modes, such as photorefractive liquid crystal cells. The approximate equations are accurate when compared to S matrix approaches and capture the plasmon propagation at the surface of the device along with the optical modes guided by the layered geometry underneath. Analysis of the resulting model provides insight into the effect of the control parameters in this device and the means to optimize the diffraction efficiency. For example, by considering the case in which the plasmon is spectrally separated from the guided modes it is possible to determine the optimum gold thickness and grating strength required to obtain the strongest possible diffraction

Metal-catalyst-free growth of silica nanowires and carbon nanotubes using Ge nanostructures

The use of Ge nanostructures is investigated for the metal-catalyst-free growth of silica nanowires and carbon nanotubes (CNTs). Silica nanowires with diameters of 10-50 nm and lengths of ? 1 ?m were grown from SiGe islands, Ge dots, and Ge nanoparticles. High-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) reveal that the nanowires grow from oxide nanoparticles on the sample surface. We propose that the growth mechanism is thermal diffusion of oxide through the GeO2 nanostructures. CNTs with diameters 0.6-2.5 nm and lengths of less than a few ?m were similarly grown by chemical vapor deposition from different types of Ge nanostructures. Raman measurements show the presence of radial breathing mode peaks and the absence of the disorder induced D-band, indicating single walled CNTs with a low defect density. HRTEM images reveal that the CNTs also grow from oxide nanoparticles, comprising a mixture of GeO2 and SiO2

On the Sequencing of Projects, Reputation Building and Relationship Finance

We study the decision entrepreneurs face in financing multiple and independent projects.If strategic defaults are assessed likely to occur, for example if judicial efficiency is low, entrepreneurs delay projects to seek sequential financing from a relationship lender.Such commitment-type borrowing allows the entrepreneur to build a private reputation for repayment and consequently reduces the cost of financing.However, if the ex-ante risk of strategic default in the economy is low, the beneffits of building a private reputation are outweighed by the holdup rents extractable by the incumbent financier.In this environment, entrepreneurs choose to finance all projects at once from single or multiple, arm's-length lenders.