Multiwavelength operation of erbium-doped fiber lasers by periodic filtering and phase modulation

This paper explains the principles behind multiwavelength operation of an erbium-doped fiber laser (EDFL) under the combined effect of cavity phase modulation and periodic wavelength filtering. A mathematical model is developed to simulate the behaviour of the multiwavelength EDFL, both in time and frequency domains. The effects of various parameters such as pump power, filter channel spacing, modulation index and frequency are observed and explained. An all-fiber EDFL was constructed, using a piezo-transducer-based phase modulator and a Sagnac loop periodic filter, to validate the theoretical results. The effects of pump power, modulation frequency and modulation index were monitored experimentally, justifying the theoretical explanation. The multiwavelength EDFL has several potential applications in fiber sensing due to its flexible all-fiber design

Policies And International Integration: Influences On Trade And Foreign Direct Investment

This paper assesses the importance of border and non-border policies for global economic integration. The focus is on four widely-advocated policies: removing explicit restrictions to trade and FDI; promoting domestic competition; improving the adaptability of labour markets; and ensuring adequate levels of infrastructure capital. The analysis covers FDI and trade in both goods and services, thus aiming to account for the most important channels of globalisation and dealing with most modes of cross-border services supply. It first describes trends in trade, FDI and the four sets of policies using a large set of structural policy indicators recently constructed by the OECD, including the new summary indicators for FDI-specific regulations described in Golub (2003). It then estimates the impact of policies on bilateral trade and bilateral and multilateral FDI. The results highlight that, despite extensive liberalisation over the past two decades, there is scope for further reducing policy barriers to integration of OECD markets. Remaining barriers have a significant impact on trade and FDI, with anticompetitive domestic regulations and restrictive labour market arrangements estimated to curb integration as much as explicit trade and FDI restrictions. Simulating the removal of such barriers suggests that the quantitative effects of further liberalisation of trade, FDI and domestic product and labour markets on global integration could be substantial

Cancellation of soft and collinear divergences in noncommutative QED

In this paper, we investigate the behavior of non-commutative IR divergences and will also discuss their cancellation in the physical cross sections. The commutative IR (soft) divergences existing in the non-planar diagrams will be examined in order to prove an all order cancellation of these divergences using the Weinberg's method. In non-commutative QED, collinear divergences due to triple photon splitting vertex, were encountered, which are shown to be canceled out by the non-commutative version of KLN theorem. This guarantees that there is no mixing between the Collinear, soft and non-commutative IR divergences