A complete and punctual Stokes polarimeter based on the conical refraction (CR) phenomenon is presented. The CR phenomenon occurs when light travels along one of the optical axes of a biaxial crystal (BC), leading to a bright ring of light at the focal plane of the system. We propose using the connection between the intensity pattern of the CR ring and the state of polarization (SOP) of the incident beam as a new tool for polarization metrology. In order to implement a complete polarimeter, the instrument is designed with a beam splitter and two BCs, one BC for each sub-beam. In the second sub-beam, a retarder is introduced before the BC, allowing us to measure the ellipticity content of the input SOP. <p> </p>The CR-based polarimeter presents several appealing features compared to standard polarimeters. To name some of them, CR polarimeters retrieve the SOP of an input beam with a single snapshot measurement, allow for substantially enhancing the data redundancy without increasing measuring time, and avoid instrumental errors related to rotating elements or active polarization devices. <p> </p>This work shows the instrument design, in particular the parameters of the set-up have been optimized in order to reduce the amplification of noise. Then, the experimental implementation of the instrument is detailed, including the experimental calibration of the system. Finally, the implemented polarimeter is experimentally tested by measuring different SOPs, including fully and partially polarized light.
Laser beams with cone-refracted output from the plane mirror is demonstrated for the first time in lasers based on intracavity conical refraction (CR) phenomenon. Transverse profile of such lasers comprises a crescent ring of CR-like distribution, where any opposite points are of orthogonal linear polarizations. We confirm the existence of such mode of CR lasers by two observations. First, cascaded CR in reflection geometry has been demonstrated for first time and it provides experimental prove that a light beam passed along optic axis of a biaxial crystal, reflected back from a plane mirror and passed again through the crystal is restored. Second, CR cavity mode with CR-like pattern through the plane mirror is experimentally and theoretically demonstrated for the first time.
Conical refraction (CR) is proposed to increase the channel capacity for free space optical communication applications.
We present the first investigations of cascaded CR with a linearly polarized input beam and experimentally prove that
two oppositely oriented consecutive identical biaxial crystals perform a forward-backward transformation of the incident
light beam. This forward-backward transformation is reported for different input beams with Gaussian, elliptical and
angularly modulated transverse intensity profiles and is the basis for our novel proposal on multiplexing and
demultiplexing of optical beams. We present experimental proof of usefulness and perspective of the CR multiplexing
technique by increasing in one order of magnitude the channel capacity at optical frequencies. The technique is
applicable to any wavelength in optical and telecommunication bands. It can be also properly upgraded with the WDM
In conical refraction, when a collimated light beam passes along the optic axis of a biaxial crystal it refracts conically
giving rise to a characteristic conical refraction (CR) ring. At each point of the CR ring the light electric field is linearly
polarized with the polarization plane rotating along the ring such that every two opposite points of the ring present
orthogonal linear polarizations. With a pinhole we have spatially filtered a small part of the CR ring and experimentally
reported that this filtered light does not yield a ring pattern when it refracts along the optic axis of a second biaxial
crystal, called the CR-analyzer in what follows. Instead, after crossing the CR-analyzer the filtered beam splits into two
beams with orthogonal linear polarizations that correspond to two opposite points of the otherwise expected CR ring. We
have experimentally derived the transformation rules of the filtered beam. For a CR-analyzer rotated by an angle ω
around the optic axis, the filtered beam splits in two beams with intensities following the fermionic transformation rule
cos<sup>2</sup> (ω / 2) , in contrast to the Malus law of cos <sup>2</sup>ω followed by double refraction.
A single three-level atom in interaction with a single longitudinal mode of a high-Q cavity is used to quantum engineer the intracavity field. In our proposal the quantum bit states correspond to the vacuum and single photon Fock states of each of two circular polarization states of the longitudinal mode. We show that for particular velocities of the three-level atom crossing the cavity it is possible to implement in one single step a two-qubit quantum phase gate between the two circular polarization states. Fidelity against several decoherence mechanisms such as atomc velocity fluctuations or the presence of a weak magnetic field along the cavity axis is analyzed.
We review amplification and lasing without inversion (AWI and LWI) in homogeneously broadened closed three-level systems in the framework of both density-matrix and quantum- jump formalisms. With the density-matrix formalism: (1) we study the nature of quantum interference in these systems; (2) determine analytically the conditions for AWI and locate the position of maxima and minima in the probe absorption spectrum; and (3) study various regimes of lasing, namely, continuous wave, self-pulsing and giant pulse lasing. Within the quantum-jump formalism we calculate the relative probabilities of the various physical processes responsible for probe field amplification and absorption.