Kamal Alameh

Plasmon-mediated magneto-optical transparency

Magnetic field control of light is among the most intriguing methods for modulation of light intensity and polarization on sub-nanosecond timescales. The implementation in nanostructured hybrid materials provides a remarkable increase of magneto-optical effects. However, so far only the enhancement of already known effects has been demonstrated in such materials. Here we postulate a novel magneto-optical phenomenon that originates solely from suitably designed nanostructured metal-dielectric material, the so-called magneto-plasmonic crystal. In this material, an incident light excites coupled plasmonic oscillations and a waveguide mode. An in-plane magnetic field allows excitation of an orthogonally polarized waveguide mode that modifies optical spectrum of the magneto-plasmonic crystal and increases its transparency. The experimentally achieved light intensity modulation reaches 24%. As the effect can potentially exceed 100%, it may have great importance for applied nanophotonics. Further, the effect allows manipulating and exciting waveguide modes by a magnetic field and light of proper polarization.

Three-Wave Fiber Fabry–Pérot Interferometer for Simultaneous Measurement of Temperature and Water Salinity of Seawater

We report a fiber sensor for simultaneous measurement of temperature and water salinity. The proposed sensor structure is based on a three-wave Fabry-Pérot interferometer (FPI) fabricated in a single-mode optical fiber (SMF) by focused ion beam (FIB) milling. The open cavity of the three-wave FPI was filled with water under test and used as the main sensing element and the lengths of the open and silica cavity were comparable. These features of the proposed sensor lead to three groups of interference fringes with distinct sensitivities in the wavelength domain with respect to the changes in both the water salinity and ambient temperature are obtained. Consequently, simultaneous determination of the ambient temperature and water salinity variations is achieved using the sensitivity matrix method.

Tuning of the transverse magneto-optical Kerr effect in magneto-plasmonic crystals

The spectral properties of the transverse magneto-optical Kerr effect (TMOKE) in periodic metal-dielectric hybrid structures are studied, in particular with respect to the achievable magnitude. It is shown that the TMOKE is sensitive to the magneto-optical activity of the bismuth-substituted rare-earth iron garnet, which is used as a dielectric material in the investigated structures. For samples with larger Bi substitution level and, consequently, larger gyration

RF magnetron sputtered (BiDy)3(FeGa)5O12:Bi2O3 composite garnet-oxide materials possessing record magneto-optic quality in the visible spectral region

Bismuth-substituted iron garnets are considered to be the most promising magneto-optical materials because of their excellent optical transparency and very high magneto-optical figures of merit in the near-infrared spectral region. However, the practical application of garnets in the visible and short-wavelength infrared parts of spectrum is currently limited, due to their very high optical absorption (especially in sputtered films) in these spectral regions. In this paper, we identify the likely source of excess absorption observed in sputtered garnet films in comparison with epitaxial layers and demonstrate (Bi,Dy)(3)(Fe,Ga)(5)O(12): Bi(2)O(3) composites possessing record MO quality in the visible region.

Magnetic photonic crystals: 1-D optimization and applications for the integrated optics devices

The optimization of multilayer one-dimensional (1-D) magnetophotonic crystals (MPCs) with multiple phase shifts, enabling their design to be tailored to practical photonics applications, is reported. The properties of sample optimized structures suitable for application in infrared intensity modulators are discussed. A novel scheme of high-resolution magnetic field sensing using MPCs is proposed. The effect of material absorption on spectral properties is shown.

Applications of liquid crystal spatial light modulators in optical communications

Advances in liquid crystal (LC) materials and VLSI technology have enabled the development of multi-phase spatial light modulators (SLM) that can perform high-resolution, dynamic optical beam positioning as well as temporal and spatial beam shaping in the 1550 nm optical communication window. These attractive features can effectively be used to achieve optical switching, optical spectral equalization, tunable optical filtering and many other functions that are important for future reconfigurable optical telecommunication networks. We review potential optical telecommunication applications based on LC-SLMs.

High-speed (2.5 Gbps) reconfigurable inter-chip optical interconnects using opto-VLSI processors

Reconfigurablele optical interconnects enable flexible and high-performance communication in multi-chip architectures to be arbitrarily adapted, leading to efficient parallel signal processing. The use of Opto-VLSI processors as beam steerers and multicasters for reconfigurable inter-chip optical interconnection is discussed. We demonstrate, as proof-of-concept, 2.5 Gbps reconfigurable optical interconnects between an 850nm vertical cavity surface emitting lasers (VCSEL) array and a photodiode (PD) array integrated onto a PCB by driving two Opto-VLSI processors with steering and multicasting digital phase holograms. The architecture is experimentally demonstrated through three scenarios showing its flexibility to perform single, multicasting, and parallel reconfigurable optical interconnects. To our knowledge, this is the first reported high-speed reconfigurable N-to-N optical interconnects architecture, which will have a significant impact on the flexibility and efficiency of large shared-memory multiprocessor machines.

Novel broadband reconfigurable optical add-drop multiplexer employing custom fiber arrays and Opto-VLSI processors

A reconfigurable optical add/drop multiplexer (ROADM) structure based on using a custom-made fiber array and an Opto-VLSI processor is proposed and demonstrated. The fiber array consists of N pairs of angled fibers corresponding to N channels, each of which can independently perform add, drop, and thru functions through a reconfigurable Opto-VLSI beam steerer. Experimental results show that the ROADM structure can attain an average add, drop/thru insertion loss of 5.5 dB and a uniformity of 0.3 dB over a wide bandwidth from 1524 nm to 1576 nm, and a drop/thru crosstalk level as small as -40 dB.

Dynamic WDM equalizer using opto-VLSI beam processing

We demonstrate an efficient wavelength-division-multiplexed (WDM) equalizer structure that uses a reconfigurable opto-very large scale integrated processor to steer/reshape many optical beams simultaneously, thus, achieving channel-by-channel equalization. The opto-VLSI processor consists of an array of liquid crystal (LC) cells independently addressed by a VLSI circuit to generate a reconfigurable reflective digital hologram. More than 30-dB dynamic range is demonstrated with a proof-of-principle three-WDM-channel equalizer.

Opto-VLSI-based tunable single-mode fiber laser.

A new tunable fiber ring laser structure employing an Opto-VLSI processor and an erbium-doped fiber amplifier (EDFA) is reported. The Opto-VLSI processor is able to dynamically select and couple a waveband from the gain spectrum of the EDFA into a fiber ring, leading to a narrow-linewidth high-quality tunable laser output. Experimental results demonstrate a tunable fiber laser of linewidth 0.05 nm and centre wavelength tuned over the C-band with a 0.05 nm step. The measured side mode suppression ratio (SMSR) is greater than 35 dB and the laser output power uniformity is better than 0.25 dB. The laser output is very stable at room temperature.