Roger Dorsinville

Polarization-sensitive quantum optical coherence tomography (PS-QOCT) is used to image and characterize birefringence effects in biological samples. Entangled photons are generated via spontaneous parametric down-conversion and split into a reference arm and a sample arm of a Mach Zehnder interferometer. Interferometric patterns between two entangled photons reveal information about tissue birefringence. Biological tissue samples are imaged and characterized, and their quantum interference patterns and birefringence profiles are presented.

We compare reconstructed quantum state images of a birefringent sample using direct quantum state tomography and inverse numerical optimization technique. Qubits are used to characterize birefringence in a flat transparent plastic sample by means of polarization sensitive measurement using density matrices of two-level quantum entangled photons. Pairs of entangled photons are generated in a type-II nonlinear crystal. About half of the generated photons interact with a birefringent sample, and coincidence counts are recorded. Coincidence rates of entangled photons are measured for a set of sixteen polarization states. Tomographic and inverse numerical techniques are used to reconstruct the density matrix, the degree of entanglement, and concurrence for each pixel of the investigated sample. An inverse numerical optimization technique is used to obtain a density matrix from measured coincidence counts with the maximum probability. Presented results highlight the experimental noise reduction, greater density matrix estimation, and overall image enhancement. The outcome of the entanglement distillation through projective measurements is a superposition of Bell states with different amplitudes. These changes are used to characterize the birefringence of a 3M tape. Well-defined concurrence and entanglement images of the birefringence are presented. Our results show that inverse numerical techniques improve overall image quality and detail resolution. The technique described in this work has many potential applications.

Polarization sensitive quantum optical coherence tomography (PS-QOCT) is used to characterize birefringence, scattering/absorption and path length differences in a flat transparent plastic sample. In this Letter, we present the first, to the best of our knowledge, experimental technique of PS-QOCT imaging and characterization of a birefringent material. Polarization sensitive coincidence rate of the entangled photons measured for each pixel and the 2D cross-sectional images are reconstructed. The technique described in this work has many potential applications in the characterization of micro and nano structures, including biological samples.

Polarization sensitive quantum optical coherence tomography (QOCT) is used to characterize birefringence and path length differences in a flat transparent plastic sample.

The implementation and performance of a unidirectional all-single mode fiber hybrid passive variable optical coupler/attenuator based on a Sagnac loop mirror with a continuous variable coupling ratio using off-the-shelf optical sub-components are discussed. Parameters of two output ports of the unidirectional hybrid passive variable optical coupler/attenuator, such as maximum coupling ratio, insertion loss, excess loss, and wavelength- dependent return loss over the C-band at room temperature are reported. The reflectivity of the Sagnac loop mirror continuously varies from 0.1% to 99.9% by adjusting retarders of a polarization controller. The 3-dB coupling ratio (i.e., 50:50) between the two output ports of the hybrid passive variable optical coupler/attenuator is achieved when the reflectivity of the Sagnac loop mirror is set at 73%. The attenuation and coupling ratio range of 1.7 - 45.5 dB and 0.13 - 99.87% is achieved, respectively, from the implemented unidirectional hybrid passive variable optical coupler/attenuator. The availability of the off-the-shelf optical sub-components and achieved easy control of continuous variable coupling ratio makes the proposed unidirectional hybrid passive variable optical coupler/attenuator a cost-effective optical device for several applications including optical system testing, and general laboratory experiments.

A simple, stable and inexpensive dual-output port widely tunable semiconductor optical amplifier (SOA)-based fiber compound-ring laser structure is demonstrated. This unique nested ring cavity enables high optical power to split into different branches where amplification and wavelength selection are achieved by using low-power SOAs and a tunable filter. Furthermore, two Sagnac loop mirrors, which are spliced at the two ends of the compound-ring cavity not only serve as variable reflectors but also channel the optical energy back to the same port without using any high optical power combiner. We propose and discuss how the demonstrated fiber compound-ring laser structure can be extended in order to achieve a high power fiber laser source by using low power optical components, such as N × N couplers and (N > 1) number of SOAs. A coherent beam-combining efficiency of over 98% for two parallel nested fiber ring resonators is achieved over the C-band tuning range of 30 nm. Optical signal-to-noise ratio (OSNR) of +45 dB, and optical power fluctuation of less than ±0.02 dB are measured over three hours at room temperature.