Walter Margulis

Fiber Bragg grating (FBG) characterization and shaping by local pressure

The spatial distribution of the chirp profile of a 4-cm-long nonuniform fiber Bragg grating (FBG) was studied with the exertion of local pressure on the fiber through the application of transverse force to a small grating section (/spl sim/0.3 mm). The technique was also used for spectrally shaping a previously unchirped, 18-cm-long Bragg grating, generating a narrow transmission window (/spl sim/400 MHz) inside its reflective band. A physical model was developed in order to estimate the phase shifts induced by pressure. A numerical simulation based on the piecewise-uniform approach was also used to calculate the consequent changes in reflected spectrum. Experimental and theoretical data show good agreement and the pressure technique proved to be adequate for grating characterization and spectral shaping.

All-fiber electrooptical polarization control

Optical fibers gain a second order nonlinearity through thermal poling. The voltage induced birefringence is small. An all-fiber Mach-Zehnder interferometer was then constructed enabling electrooptical polarization control with 78 V and sub-microsecond response time.

Internal electrode fiber polarization controller

With the growing importance of optics in access and metro networks, the need for inexpensive high-performance optical components becomes more acute. One of the essential functions required is polarization control. Manually, motorized or piezoelectric actuated controllers exist in the market, based on the stress induced in the fiber by an external element. In this paper, we present the principles and performance of a polarization controller based on the stress induced by an internal current driven electrode. Mach-Zehnder interferometer is used for implementing a 2/spl times/2 fiber switch.

Making graphene visible on transparent dielectric substrates: Brewster angle imaging

The visibility of graphene is greatly increased by illuminating samples deposited on transparent dielectrics at the substrates Brewster angle. Using a commercial ellipsometer, the reflectivity of monolayers of chemical vapour deposition (CVD) graphene is found to be up to 33 times higher than that of the substrate, i.e., an optical contrast as high as 3200% is obtained, more than 380 times higher than with standard optical microscopy. Also, with a simpler, homemade, experimental setup, a 1400% optical contrast was measured for a monolayer of CVD graphene and linear features as small as ~20 μm were visible in a monolayer, while ~6 × 17 μm2 trilayers could still be imaged in exfoliated samples. It is also shown that the reflectance/transmittance ratio increases quadratically with the number of graphene layers, which may allow for counting layer numbers and identifying wrinkles and folds in transferred samples.

Microsecond switching of plasmonic nanorods in an all-fiber optofluidic component

As information technologies move from electron-to photon-based systems, the need to rapidly modulate light is of paramount importance. Here, we study the evolution of the electric-field-induced ali ...

High-Speed Control of Fiber Bragg Gratings

FBGs were written in fiber with internal alloy electrodes. Nanosecond high current pulses cause metal expansion, increase birefringence and tune the gratings. High-speed wavelength switching was accomplished with potential use in Q-switching fiber lasers.

All-Fiber Q-Switched and Cavity Dumped Laser Using an Electrically Addressed Microstructured Fiber

We report on a pulsed fiber laser with two regimes of operation, one where cavity-roundtrip pulse durations are produced (85 ns long, 40 Wpp) and one with high power pulses (2 ns long, 148 Wpp).

Specialty Single-Mode Fibers

This chapter provides an overview of unusual multifunctional, specialty single-mode fibers-macrohole fibers, multicore fibers, fibers with internal electrodes, and fibers for high-temperature resis ...

Electrically controlled Bragg grating in microstructured fiber with internal electrode

Microstructured fibers with internal electrode provide a new, flexible means for shaping the spectral properties of intracore gratings. In particular, control of the current that is applied to electrode permits modifies the central wavelength and the birefringence of the grating. The fabrication procedures for this type of device and experimental results related to its operation are described.

Comparison of characterization techniques and the effect of surface condition in poled silica

Four characterization techniques are compared in the measurement of the depletion region of silica poled during different time intervals. The effect of pre-etching the samples prior to poling is also investigated.