All-fiber laser mode-locked by the acousto-optic modulation of a fiber Bragg grating in suspended core fiber

An ytterbium-doped fiber laser mode-locked by the interaction of a fiber Bragg grating and longitudinal acoustic waves in a suspended core fiber is experimentally investigated. An optimized design of an acousto-optic modulator is also proposed. The results indicate output pulses with a width of less than 550 ps at a repetition rate of 10 MHz. The reduction of the power consumed by the transducer and the grating length points out to more efficient, compact and fast acousto-optic modulators for mode-locked all-fiber lasers

Inverse scattering approach to characterize capillary optical fibers

We characterize capillary optical fibers by a coherent side illumination technique and retrieve the diameters of the capillary and cladding with approximately 100 nm accuracy

High performance fiber-Fabry-Perot resonator targeting quantum optics applications

Quantum optics experiments frequently require the separation of single-photon-level signals from strong classical fields. In circumstances in which the signals are spectrally close, and one cannot make use of relatively simple separation methods based around differences in polarization state, optical mode, or beam direction, it is necessary to exploit the frequency difference itself as the means for signal separation. We have constructed and characterized an efficient and robust fiber-based filter, consisting of an all-fiber Fabry-Perot resonator, to achieve this goal. Our filter shows 31dB of suppression of unwanted signals and 76% transmission of the desired signal. The transmission of the filter was stabilized to within 2% of its maximum for over 35hours through simple temperature stabilization.Jonathan P. Hedger, Tino Elsmann, Martin Becker, Tobias Tiess, Andre N. Luiten and Ben M. Sparke

Detailed Investigation Of Mode-Field Adapters Utilizing Multimode-Interference In Graded Index Fibers

We present a detailed study of mode-field adapters (MFA) based on multimode interference in graded index multimode fibers. We have fabricated and characterized MFAs from a selection of commercially available single-mode and graded index fibers. Compared to existing techniques, the presented MFAs can be fabricated very quickly and are not limited to certain fiber types. Insertion losses of $\u3c 0.5$ dB over a spectral range of several hundred nanometers have been obtained, which is comparable or better than the industry standard. © 2012 IEEE

Noninvasive characterization of optical fibers

Capillary optical fibers with hole diameters of several micrometers are important for novel plasmonic applications and medical diagnosis. In order to ensure the optical functionality of these fibers, the diameter of the capillary hole needs to be realized with high accuracy. Here, we introduce a novel and noninvasive methodology to characterize optical fibers and discuss it for the assessment of capillaries. In this method, the fiber is side-illuminated by a coherent beam, and the resulting diffraction pattern is analyzed. This corresponds to an in-line holographic measurement in the presence of strong scattering. A numerical parameter retrieval allows us to characterize the capillary hole diameter with an accuracy of approximately 100 nm for radii between several hundreds of nanometers and several tens of micrometers

Wave-optical modeling beyond the thin-element-approximation

The optical design and analysis of modern micro-optical elements with high index contrasts and large numerical apertures is still challenging, as fast and accurate wave-optical simulations beyond the thin-element-approximation are required. We introduce a modified formulation of the wave-propagation-method and assess its performance in comparison to different beam-propagation-methods with respect to accuracy, required sampling densities, and computational performance. For typical micro-optical components, the wave-propagation-method is found to be considerably faster and more accurate at even lower sampling densities compared to the different beam-propagation-methods. This enables realistic wave-optical simulations beyond the thin-element-approximation for micro-optical components. As an example, the modified wave-propagation-method is applied for in-line holographic measurements of strongly diffracting objects. From a direct comparison of experimental results and corre sponding simulations, the geometric parameters of a test object could be retrieved with high accuracy