Holographic Fabry-Perot spectrometer.
We propose a spectrum analyzer based on the properties of a hologram recorded with the field transmitted by a Fabry-Perot etalon. The spectral response of this holographic Fabry-Perot spectrometer (HFPS) is analytically investigated in the paraxial approximation and compared with a conventional Fabry-Perot etalon of similar characteristics. We demonstrate that the resolving power is twice increased and the free spectral range (FSR) is reduced to one-half. The proposed spectrometer could improve the operational performance of the etalon because it can exhibit high efficiency and it would be insensible to environmental conditions such as temperature and vibrations. Our analysis also extends to another variant of the HFPS based on holographic multiplexing of the transmitted field of a Fabry-Perot etalon. This device increases the FSR, keeping the same HFPS performance.
High resolution coherent spectral analysis method based on Brillouin scattering in an optical fiber.
High-resolution optical spectral analysis method is of significant importance for those who want to explore the physical world from the frequency domain. Aiming at the resolution degradation of classical coherent optical spectrum analysis (COSA) caused by the mirror phenomenon, this paper modifies the COSA system by introducing two homologous Brillouin scattering beams to serve as the pre-filter and local oscillator (LO), respectively. The central frequencies of the pre-filtered signal and the LO are locked by the Brillouin frequency shifts of those two Brillouin scattering beams. By means of this modification, the pre-filtered signal is located at either the upper-frequency-shifted side or the lower-frequency-shifted sides of the LO but could not exist on both sides of the LO. The proposed method could cancel the mirror phenomenon and thus improve the systematic resolution to 1.3 MHz in theory and 2 MHz in practice.
The Open Mobile Alliance: Delivering Service Enablers for Next-Generation Applications
Apractical overview of OMA specifications and how they enable mobile multimedia services & much more ! The Open Mobile Alliance (OMA) is an industry forum, which develops open specifications to help in the creation of applications and services to be deployed over converged networks. The alliance is the leading industry forum for generating market-driven specifications for interoperable mobile service enablers that facilitate global user adoptions of mobile multimedia services. Members include traditional wireless industry segments, such as mobile operators mobile operators (e.g. AT&T, China Mobile, Orange, Sprint Nextel, T-Mobile, Telefonica, Vodafone), equipment and mobile systems manufacturers (e.g. Alcatel-Lucent, Ericsson, Motorola, Nokia, Philips, Samsung, Siemens, Sony-Ericsson), and Information Technology vendors (e.g. BEA Systems, IBM, Microsoft, Oracle Corporation, Sun Microsystems and NEC). Since its formation in 2002, the OMA has made significant progress in areas such as push-to-talk over cellular, device management, presence and group management, and messaging. The Open Mobile Alliance: Provides a comprehensive overview of the service enablers published by the OMA, tying together all the different piece parts developed by the individual working groups Offers a thorough introduction to the OMA Service Environments (OSE) and the specification process for enabling technologies. Discusses enablers for services such as gaming, IMS, Parlay, mobile broadcast and web services. Contains contributions from all stakeholders in the mobile application value chain. The Open Mobile Alliance Alliance is an invaluable resource for OMA members, product managers, network architects and planners, standards managers, standards engineers and IT professionals. Advanced Students and lecturers on mobile application development and standardization courses will also find this book of interest."The success of OMA is due to its individual members' contributions, and this book is testament to their hard work. The individual members' efforts and the authors of this book are to be congratulated on their magnificent achievements." Mark Cataldo, Senior Advisor, Orange SA, OMA Technical Plenary Chairman