Real-Time Birefringence Measurement with Digital Holographic Microscopy

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Chirality is a property which is widely observed in nature and refers to the characteristic that an object cannot be superimposed on its mirror image. Recently, chiral solution-processable semiconductors have seen a surge of interest for their potential applications in emerging photonic, optoelectronic and spintronic technologies [1]. Yet, the underlying chiral light-matter interactions, especially in the excited state, which lead to spin and light polarization remain poorly understood [2]. Here, we presen

We experimentally verify the possibility of measuring the difference in effective refractive index between higher-order-modes using a phase-sensitive OTDR, indicating that it is possible to measure the average difference over long fiber spans.

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The generation of pulses in dual-pump fiber optical parametric amplifier is investigated. Theoretically, it is shown that in an analogical manner to pulse generation in single-pump fiber optical parametric amplifiers, the generated pulse shape depends on the linear phase mismatch between the interacting waves. However the dual-pump architecture allows for the bounding of the phase mismatch over a wide bandwidth. This feature permits the generation of uniform pulses over a wide bandwidth, contrary to the sin

Using optical fiber amplification and phase modulation, we demonstrate experimentally the generation of pulses with characteristics that are close to Nyquist limited sinc pulses. Bandwidth limited pulses of full width half maximum less than 17 ps at 10 GHz repetition rate are achieved.

We present a theory stating how to overcome the classical Rayleigh-resolution limit. It is based upon a new resolution criterion in phase of coherent imaging process and its spatial resolution is thought to be only SNR limited. Recently, the experimental observation of systematically occurring phase singularities in coherent imaging of sub-Rayleigh distanced objects has been reported.1 The phase resolution criterion relies on the unique occurrence of phase singularities. A priori, coherent imaging system's

We report coupled VCSEL arrays, emitting at 1.3μm wavelength, in which both the optical gain/loss and refractive index distributions were defined on different vertical layers. The arrays were electrically pumped through a patterned tunnel junction, whereas the array pixels were realized by intra-cavity patterning using sub-wavelength air gaps. Stable oscillations in coupled modes were evidenced for 2x2 array structures, from threshold current up to thermal roll-over, using spectrally resolved field pattern

The piezoelectric properties of tetragonal BaTiO3 (BTO) crystals with a high density of 90° twin domain boundaries were experimentally investigated by Wada and Tsurumi (2004 Br. Ceram. Trans. 103 93). These crystals with engineered dense domain structures exhibit significantly larger intrinsic d33 and d31 coefficients than in mono-domain crystals. This phenomena was studied theoretically and several enhancement mechanisms (domain wall broadening, polarization tilting) were suggested in the past, but no sati

Digital holographic microscopy (DHM) is a technique that allows obtaining, from a single recorded hologram, quantitative phase image of living cell with interferometric accuracy. Specifically the optical phase shift induced by the specimen on the transmitted wave front can be regarded as a powerful endogenous contrast agent, depending on both the thickness and the refractive index of the sample. We have recently proposed a new and efficient decoupling procedure allowing to directly obtain separate measureme

Digital Holographic Microscopy (DHM) is a powerful imaging technique allowing, from a single amplitude image (amplitude and phase), reflected acquisition (hologram), the reconstruction of the entire complex wave front by or transmitted through an object. Because holography is an interferometric technique, the reconstructed phase leads to a sub-wavelength axial accuracy (below lambda/100). Nevertheless, this accuracy is difficult to obtain from a single hologram. Indeed, the reconstruction process consisting

We describe a new method for performing simultaneous position-resolved measurements of chromatic dispersion and Brillouin shift along single-mode optical fibers. The technique provides consistent high-resolution and low-noise results for both quantities. Our measurements indicate a certain correlation between both magnitudes, although the degree of correlation varies for the different manufacturers tested.

We have employed femtosecond laser writing in order to induce refractive-index changes and waveguides in Ti3+-doped sapphire. Doping the sapphire crystal with an appropriate ion significantly reduces the threshold for creating structural changes, thus enabling the writing of waveguide structures. Passive and active buried channel waveguiding is demonstrated and images of the guided modes, propagation-loss values, fluorescence spectra, and output efficiencies are presented. The guiding area is located around

A new method for chromatic dispersion mapping in optical fibers is presented. It is based on measuring the CW four-wave mixing distribution created by two beams along the fiber using a Brillouin-OTDA. Experimental results demonstrate the feasibility of the technique

Stress-induced changes in the imprint and switching behavior of (111)-oriented Pb(Zr,Ti)O-3 (PZT)-based capacitors have been studied using piezoresponse force microscopy. Visualization of polarization distribution and d(33)-loop measurements in individual 1x1.5-mum(2) capacitors before and after stress application, generated by substrate bending, provided direct experimental evidence of stress-induced switching. Mechanical stress caused elastic switching in capacitors with the direction of the resulting pol

An optical fiber Bragg grating (FBG) embedded in an epoxy matrix is indubitably subjected to non-negligible residual stresses arising from the cure, especially for a strong fiber-matrix interface. The spectral response of the FBG sensor is clearly influenced by the presence of the residual non-homogeneous strain field along the grating and results in a distortion (chirp) of the reflected spectrum. Direct applications for distributed strain sensing, without tracking the residual field into account, can lead

We report quantitative dissociation yields for the reaction CH3OH (v(OH))-->nhnu CH3+OH induced by infrared multiphoton excitation of methanol pre-excited to various levels of the OH stretching vibration (v(OH)=0, 1, 3, 5). The yields are measured by detecting OH using laser induced fluorescence. It is demonstrated that for low levels of pre-excitation (v(OH)=0, 1, 3) there is a substantial nonlinear intensity dependence, as a higher yield is found for self mode-locked CO2 laser pulses (with higher peak int

The development of internal stress during cure of epoxy and hyperbranched polymer- modified epoxy resins was characterized, taking into account the evolving viscoelastic properties, the volumetric shrinkage due to the chemical reaction, and the thermal expansion. A criterion for void formation during cure in a constrained mold was proposed, providing guidelines for the construction of a process window for manufacturing of void-free composites. It was shown that the internal stress development in epoxy resin

A numerical holographic method, which is able to determine the amplitude components of the Jones vector of a wavefront in addition to its phase and amplitude, is presented. Two reference waves, with orthogonal polarisations interfere with the transmitted or reflected object wave to create the hologram that is recorded on a standard CCD camera. Two wavefronts, one for each perpendicular polarisation state, are numerically reconstructed in intensity. Combining the intensity distribution of these two wavefront

A novel experimental setup for injection-locking experiments is presented. The single-mode-fiber-based configuration allows one to precisely control the power and the polarization state of the light injected from the master laser into the slave laser cavity. Different behaviors typical for injection locking with single-mode semiconductor lasers (e.g., stable injection locking, undamped relaxation oscillations, nearly degenerate four-wave mixing, period doubling, chaotic behavior) are experimentally observed

A new class of active fiber devices based on piezoelectric coated optical fibers is currently being developed. The piezoelectric coating is used to produce acoustic waves within the optical fiber and these acoustic waves interfere with optical signals passing through the fiber waveguide. Optical phase modulation devices based on piezoelectric coated fibers have been demonstrated and the behavior of these devices will be reviewed. A second type of active optical fiber device has been fabricated by integratin

Real-Time Birefringence Measurement with Digital Holographic Microscopy

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Chiral light-matter interactions in molecular semiconductors

Intermodal measurements in few-mode fibers with phase- sensitive OTDR

State-Of-The-Art of Research on Distributed Optical Fibre Sensors

Wideband generation of pulses in dual-pump optical parametric amplifier: theory and experiment

Near-Nyquist sinc shaped optical pulse generation in fiber optical parametric amplifier

Beyond the lateral resolution limit by phase imaging

Intra-cavity patterning for mode control in 1.3μm coupled VCSEL arrays

The stress-assisted enhancement of piezoelectric properties due to mechanically incompatible domain structures in BaTiO3

Erythrocytes volume and refractive index measurement with a digital holographic microscope

Automatic procedure for aberrations compensation in digital holographic microscopy

Simultaneous position-resolved mapping of chromatic dispersion and Brillouin shift along single-mode optical fibers

Femtosecond-irradiation-induced refractive-index changes and channel waveguiding in bulk Ti3+: Sapphire

Chromatic dispersion mapping by sensing the power distribution of four-wave mixing along the fiber using Brillouin probing

Mechanical stress effect on imprint behavior of integrated ferroelectric capacitors

Modeling of the residual stresses acting on a low-birefringence fiber Bragg grating sensor embeded in an epoxy matrix

Nonlinear intensity dependence in the infrared multiphoton excitation and dissociation of methanol pre-excited to different energies

Internal Stress Control in Epoxy Resins and their Composites by Material and Process Tailoring

A method for polarisation imaging using digital holography

Novel measurement scheme for injection-locking experiments

Piezoelectric coatings for active optical fiber devices