Polarization

Jochen Pade

Ziyao Lyu, Tao Dong, Yijie Du +2 more

Polarization imaging is essential to reveal rich information of the vectorial nature of microwaves. However, selective imaging of specific polarization components with subwavelength resolution remains challenging. Here, we propose atom-based polarization holography for all-optical polarization-filtered subwavelength imaging in microwave regime. A kind of atomic polarization holograms is recorded through two-photon excited anisotropy in a four-level quantum system and its diffraction properties are characterized using Jones theory combined with optical Bloch equation. It is found that the polarization information of microwaves can be actively manipulated to holographic diffracted light fields. Moreover, polarization imaging of atom-based polarization holography with a spatial resolution of one-fortieth wavelength (λ/40) has been realized experimentally through microwave-to-optical conversion. The function of polarization filtering is demonstrated by optical holographic diffraction and the microwave component with specific polarization state can be selectively imaged from superimposed polarized microwaves. Our work is expected to enable applications in polarization filtering and subwavelength imaging. Polarization imaging reveals vectorial nature of microwaves, but selective imaging of specific polarization components with subwavelength resolution remains challenging. The authors propose atom-based polarization holography to optically filter microwave polarizations from complex mixed signals via holographic diffraction, achieving λ/40 imaging resolution.

Abel Lorences-Riesgo, Peter A. Andrekson, Magnus Karlsson

We thoroughly analyze the requirements on the signal and idler state of polarizations (SOPs) for achieving maximum amplification in phase-sensitive amplifiers (PSAs). These requirements are described using a Jones-space description as well as a Stokes-space description. Our analysis includes the cases of polarization-diverse and vector PSAs, and in each type of PSA, we also consider the signal-degenerate and the non-degenerate schemes. We observe that the relation between the signal and idler SOPs to achieve maximum phase-sensitive (PS) amplification can be described similarly in polarization-diverse and in vector PSAs. Moreover, both types of PSAs are polarization-dependent, which means that PSAs do require polarization-tracking schemes when being implemented in a realistic optical-transmission scenario. We therefore evaluate how polarization tracking of the signal and the idler SOPs can overcome the theoretical polarization dependence of both polarization-diverse and vector PSAs. We find that only one polarization tracker for either the signal or idler SOP is necessary for achieving polarization-independent PS amplification when considering the general case of dual-polarization (DP) modulated signals. This polarization tracker requires the control of three degrees of freedom which describe a general polarization rotation. For single-polarization (SP) modulated signals, the polarization tracker can rotate both the signal and the idler SOPs simultaneously which eliminates the need for splitting the signal and the idler before the PSA. Moreover, only two degrees of freedom for the polarization tracker are necessary in this case. When considering degenerate schemes, a polarization tracker with two degrees of freedom is sufficient to achieve maximum PS amplification of DP binary phase-shift keying (BPSK) signals in both vector and polarization diverse PSAs. For the case of SP-BPSK signals, a polarization-diverse PSA can perform polarization-independent amplification by controlling the relative phase between the pumps, whereas a polarization tracker with only one degree of freedom is necessary in the case of vector PSAs.

Jochen Pade

Jochen Pade

Dongshi Guan, Jun Xiong, Su-Heng Zhang +2 more

This article studies,both theoretically and experimentally,how the degree of polarization and the polarization state of polarized light affect the normalized second order correlation g(2) in Hanbury Brown-Twiss experiment.In the experiment,the plane polarized light is changed into elliptically polarized light by passing it through a 1/4 wave plate.By rotating the wave plate,the polarization state of light can be changed.Two beams of light with mutually perpendicular vibration direction,same propagation direction and random phase difference are compounded into a partly polarized light.By adjusting the intensity of one beam of the light,the degree of polarization can be changed.It is shown that for polarized light,the state of polarization causes no change in g(2).On the other hand,for light with different degrees of polarization(P),g(2) is a quadratic function of P.For natural light,P=0,and the maximum g(2) in theory is 1.5;for polarized light,P=1,and the maximum g(2) in theory is 2.