Symmetrical dual-sideband oppositely chirped differential FMCW LiDAR.

A differential FMCW LiDAR for high-precision distance measurements of remote non-stationary targets is proposed and demonstrated experimentally. The required positive and negative symmetrically oppositely chirped laser beams are generated synchronously through a fixed-frequency laser by employing externally unified broadband optical phase modulation and symmetrical dual-sideband optical filtering. After coaxial transmission and reception, orthogonally polarized optical beat signals containing target distance and vector velocity data are de-chirped separately by optical in-phase and quadrature demodulations and then synchronously received by four-channel photoelectric balance detectors.

Real-time acquisition and enhancement of remote acoustic signals by a free-space monostatic homodyne laser Doppler vibrometer.

This paper systematically presents the design and performance of an extremely sensitive 1.55-µm free-space monostatic laser Doppler vibrometer (LDV) using optical homodyne detection for real-time acquisition and enhancement of the remote acoustic signals. The phase shifts produced by laser light scattered off a remote target carries the extremely tiny vibration displacement information of the target' surface motivated by the acoustic source around and is demodulated using the optical in-phase/quadrature demodulator.

Polarization state dependence of laser-induced domain nucleation in lithium niobate crystals investigated by digital holography.

This paper systematically investigates the influences of polarization states on laser-induced domain nucleation in z-cut crystals. The real-time 2D and 3D phase distributions at the focus during laser-induced domain nucleation were reconstructed by digital holography. The different samples, including undoped congruent , Mg-doped congruent , Hf-doped congruent , and stoichiometric , were tested.

Optical method to determine the composition of lithium niobate crystals by digital holography.

Because the physical properties of lithium niobate () strongly depend on composition, accurate and convenient methods for the determination of the composition are of great significance. Although several optical methods, including the measurement of UV absorption edge, the birefringence, and the second-harmonic generation, have been proved to be convenient for an accurate and fast standard determination of composition in single crystals, their research and commercial applications are limited by the doping component and the complex nonlinear relationships. Based on preliminary work, a novel optical method to determine the composition of crystals by digital holography is proposed.

Objective shearing digital holography for removing aberration from optical system.

We propose a new digital holography based on the lateral shearing interference concept to remove the total aberrations from the reference wave, illumination wave, and the optical elements. It uses three mutually shifted image holograms of the object that are divided from each other to obtain phase differences. The phase aberration can be removed and the original sample phase can be reconstructed by the phase differences.

Localized propagation modes guided by shear discontinuities in photonic crystals.

We propose and analyze shear discontinuities as a new type of defect in photonic crystals. This defect can support guided modes with minimum group velocity dispersion (GVD) and maximum bandwidth, provided that the shear shift equals half the lattice constant. A mode gap emerges when the shear shift is different than half the lattice constant.

Diffraction from deformed volume holograms: perturbation theory approach.

We derive the response of a volume grating to arbitrary small deformations, using a perturbative approach. This result is of interest for two applications: (a) when a deformation is undesirable and one seeks to minimize the diffracted field's sensitivity to it and (b) when the deformation itself is the quantity of interest and the diffracted field is used as a probe into the deformed volume where the hologram was originally recorded. We show that our result is consistent with previous derivations motivated by the phenomenon of shrinkage in photopolymer holographic materials.

Cross talk in resonant holographic memories.

We analyze cross talk in resonant holographic memories and derive the conditions under which resonance improves storage quality. We also carry out the analysis for both plane-wave and apodized Gaussian reference beams.

Coherence patterns originating from incoherent volume sources.

We derive the complex degree of coherence that originates from generalized incoherent two- and three-dimensional sources. Further, we find the locus of maximum coherence and analyze the dependence of the decay of coherence on source thickness.