Watt-level narrow-linewidth fibered laser source at 852 nm for FIB application.

We realize a 1 W all-fibered polarized compact and robust laser source at 852 nm for laser cooling of cesium atoms. The architecture is based on the sum-frequency generation of 1540 and 1908 nm lasers, realized through a periodically poled lithium niobate waveguide with a conversion efficiency of 40%. A linewidth of 20 kHz is achieved with the development of a distributed feedback fiber laser at 1908 nm. The operation of this laser source is demonstrated on a focused ion beam (FIB) experiment based on cold cesium atoms.

Beat note stabilization in dual-polarization DFB fiber lasers by an optical phase-locked loop.

A fully fibered microwave-optical source at 1.5 µm is studied experimentally. It is shown that the beat note between two orthogonally polarized modes of a distributed-feedback fiber laser can be efficiently stabilized using an optical phase-locked loop. The pump-power-induced birefringence serves as the actuator. Beat notes at 1 GHz and 10 GHz are successfully stabilized to a reference synthesizer, passing from the 3 kHz free-running linewidth to a stabilized sub-Hz linewidth, with a phase noise as low as -75 dBc/Hz at 100 Hz offset from the carrier. Such dual-frequency stabilized lasers could provide compact integrated components for RF and microwave photonics applications.

Watt-level single-frequency tunable neodymium MOPA fiber laser operating at 915-937 nm.

We have developed a Watt-level single-frequency tunable fiber laser in the 915-937 nm spectral window. The laser is based on a neodymium-doped fiber master oscillator power amplifier architecture, with two amplification stages using a 20 mW extended cavity diode laser as seed. The system output power is higher than 2 W from 921 to 933 nm, with a stability better than 1.4% and a low relative intensity noise.

Extended tunability of Nd-doped fiber lasers operating at 872-936 nm.

Efficient operation of an Nd-doped fiber laser operating in a wavelength-tunable configuration using a volume Bragg grating (VBG) is reported in this Letter. A high-power operation on the 4F3/2-4I9/2 transition of Nd3+ at short wavelengths below 900 nm is demonstrated for the first time in silica fibers. A high-efficiency (47% laser conversion) output power up to 22 W and a narrow linewidth of 0.035 nm are achieved. This configuration is compared with a more conventional fiber laser setup using a bandpass filter and a highly reflective dichroic mirror.

Radiation-hard erbium optical fiber and fiber amplifier for both low- and high-dose space missions.

We present a new structure for erbium-doped optical fibers [hole-assisted carbon-coated, (HACC)] that, combined with an appropriate choice of codopants in the core, strongly enhances their radiation tolerance. We built an erbium-doped fiber amplifier based on this HACC fiber and characterize its degradation under γ-ray doses up to 315 krad (SiO2) in the ON mode. The 31 dB amplifier is practically radiation insensitive, with a gain change of merely -2.2×10(-3) dB/krad. These performances authorize the use of HACC doped fibers and amplifiers for various applications in environments associated with today's missions (of doses up to 50 krad) and even for future space missions associated with higher dose constraints.

20 W continuous-wave cladding-pumped Nd-doped fiber laser at 910 nm.

We demonstrate a double-clad fiber laser operating at 910 nm with a record power of 20 W. Laser emission on the three-level scheme is enabled by the combination of a small inner cladding-to-core diameter ratio and a high brightness pump source at 808 nm. A laser conversion efficiency as high as 44% was achieved in CW operating regime by using resonant fiber Bragg reflectors at 910 nm that prevent the lasing at the 1060 nm competing wavelength. Furthermore, in a master oscillator power-amplifier scheme, an amplified power of 14.8 W was achieved at 914 nm in the same fiber.

The diversity of regulation and public financing of IVF in Europe and its impact on utilization.

STUDY QUESTION: How do the different forms of regulation and public financing of IVF affect utilization in otherwise similar European welfare state systems? SUMMARY ANSWER: Countries with more liberal social eligibility regulations had higher levels of IVF utilization, which diminished as the countries' policies became more restrictive. WHAT IS KNOWN ALREADY: Europe is a world leader in the development and utilization of IVF, yet surveillance reveals significant differences in uptake among countries which have adopted different approaches to the regulation and and public financing of IVF. STUDY DESIGN, SIZE, DURATION: A descriptive and comparative analysis of legal restrictions on access to IVF in 13 of the EU15 countries that affirmatively regulate and publicly finance IVF. PARTICIPANTS/MATERIALS, SETTING, METHODS: Using 2009 data from the European Society of Human Reproduction and Embryology study of regulatory frameworks in Europe and additional legislative research, we examined and described restrictions on access to IVF in terms of general eligibility, public financing and the scope of available services. Multiple correspondence analysis was used to identify patterns of regulation and groups of countries with similar regulatory patterns and to explore the effects on utilization of IVF, using data from the most recent European and international IVF monitoring reports. MAIN RESULTS AND THE ROLE OF CHANCE: Regulations based on social characteristics of treatment seekers who are not applicable to other medical treatments, including relationship status and sexual orientation, appear to have the greatest impact on utilization. Countries with the most generous public financing schemes tend to restrict access to covered IVF to a greater degree. However, no link could be established between IVF utilization and the manner in which coverage was regulated or the level of public financing. LIMITATIONS, REASONS FOR CAUTION: Owing to the lack of data regarding the actual level of public versus private financing of IVF it is impossible to draw conclusions regarding equity of access. Moreover, the regulatory and utilization data were not completely temporally matched in what can be a quickly changing regulatory landscape. WIDER IMPLICATIONS OF THE FINDINGS: Whether motivated by cost, eligility restrictions or the availability of particular services, cross-border treatment seeking is driven by regulatory policies, underscoring the extra-territorial implications of in-country political decisions regarding access to IVF. STUDY FUNDING/COMPETING INTEREST(S): There was no funding source for this study. The authors have no conflicts of interest to declare.

Generation of 520 mW pulsed blue light by frequency doubling of an all-fiberized 978 nm Yb-doped fiber laser source.

Pulsed blue light at 489 nm has been generated by second-harmonic-generation of a nanosecond pulsed master-oscillator power amplifier system based on a short Yb(3+) doped single-mode fiber amplifier at 978 nm and an external-cavity diode laser as seed source. The Yb(3+)-doped fiber was core-pumped by a W type Nd(3+) doped double-clad fiber laser operating on the transition near 930 nm ((4)F(3/2)→(4)I(9/2)). 520 mW of average power was generated at 489 nm using a periodically poled MgO:LiNbO(3), corresponding to a conversion efficiency of 34%.