Optical polarisation state control schemes using fibre optics or Bragg cells

Miniature Surface Plasmon Polariton Amplitude Modulator by Beat Frequency and Polarization Control

The miniaturization of modulators keeps pace for the compact devices in optical applications. Here, we present a miniature surface plasmon polariton amplitude modulator (SPPAM) by directing and interfering surface plasmon polaritons on a nanofabricated chip. Our results show that this SPPAM enables two kinds of modulations. The first kind of modulation is controlled by encoding angular-frequency difference from a Zeeman laser, with a beat frequency of 1.66 MHz; the second of modulation is validated by periodically varying the polarization states from a polarization generator, with rotation frequencies of 0.5–10 k Hz. In addition, the normalized extinction ratio of our plasmonic structure reaches 100. Such miniaturized beat-frequency and polarization-controlled amplitude modulators open an avenue for the exploration of ultrasensitive nanosensors, nanocircuits, and other integrated nanophotonic devices.

Precise optical activity measurement of quartz plate by using a true phase-sensitive technique

A method of considering the circular and linear birefringent properties of a material on the basis of circular and linear polarization eigenstates is presented theoretically and experimentally. A polarized common-path optical heterodyne interferometer with respect to both right-hand and left-hand circularly polarized light was set up. It was used in conjunction with a phase lock-in technique to measure the optical activity of quartz crystal in real time. The signal-to-noise ratio of the measured phase change caused by the lateral displacement of quartz cornus was 75, which corresponded to a measuring accuracy of 10(-7). This novel method, in which a true-phase-sensitive optical heterodyne interferometer is used, has higher detection sensitivity and higher immunity to environmental disturbances.