The ability to see inside the body noninvasively is indispensable in modern biology and medicine. Optical approaches to such abilities are of rapidly growing interest because of their nonionizing nature and low cost. However, the problem of opacity due to the optical turbidity of tissues must be addressed before optical means become practical. Harmonic holography amalgamates the capability of h...

We demonstrate experimentally that optical phase conjugation can be used to focus light through strongly scattering media even when far less than a photon per optical degree of freedom is detected. We found that the best achievable intensity contrast is equal to the total number of detected photons, as long as the resolution of the system is high enough. Our results demonstrate that phase conju...

We predict that the efficiency of the optical phase conjugation generation can be enhanced by more than four orders of magnitude in a xs3d nonlinear superlattice, as compared with that in a homogeneous nonlinear medium of the same sample thickness and xs3d nonlinearity. Such an effective enhancement utilizes the localized properties of the fields inside the sample at the band-edge state, gap-so...

r-phycoerythrin (r-pe), a fluorescent protein from phycobiliprotein family, is isolated from red algae. conjugation of antibodies to r-pe facilitates multiple fluorescent staining methods. in the present study polyclonal antibodies and polyclonal f(ab')2 fragment antibodies were conjugated to r-pe by two different methods. the efficiency of the methods was evaluated using immunocytochemistry (i...

We show that topologically protected defect states can exist in open (leaky or lossy) systems even when these systems are topologically trivial in the closed limit. The states appear from within the continuum, thus in the absence of a band gap, and are generated via exceptional points (a spectral transition that occurs in open wave and quantum systems with a generalized time-reversal symmetry),...

A theory of phase conjugation in asymmetric materials that allow a phase shift between the grating and the light-interference pattern is developed. We find that when this phase is nonzero, maximum phase-conjugate reflectivity occurs for unequal pump intensities. The conditions for self-oscillation are studied.