Pirelli Cavi E Sistemi S.p.a.

Angelo Barberis

Mario Martinelli

Paolo Martelli

Silvia Maria Pietralunga

Stefano Caselli

In an interferometer configuration, a retarder in the form of a half-wave plate () and a phase shifter in the form of a glass plate () are arranged in one arm (). The phase shifter provides an optical path difference between the interferometer arms which needs to be greater than the coherence length of the input light to be polarization stabilized. A polarizer in the form of a linear polarizer () aligned at 45&#xb0; to the half-wave plate is arranged across both interferometer arms (&). Polarization stabilization action is achieved by the retarder in combination with the polarizer. More specifically, for at least one input polarization state, the polarization states in the two interferometer arms are rendered orthogonal by the retarder, the polarizer being aligned to allow only one of the two orthogonal states to be transmitted, the other being absorbed. The device is expected to find application for WDM networks based on broadband sources, such as superluminescent diodes. The device is also expected to be useful for providing a front-end polarization stabilization of the signal supplied to optical elements that are sensitive to the polarization state of their input. Examples of such elements are semiconductor optical amplifiers, integrated optical splitters and electro-optical switches.

Passive polarization stabilizer

There is provided a method and apparatus for measuring the optical properties of bulk samples. A probe laser beam is fed into the two arms of the apparatus, a reference arm and a measurement arm, both of which contain optical fiber to conduct the laser lights. The measurement arm includes a free space area for mounting a sample to be tested. The probe beam is directed into the sample in free space. The sample also receives light in free space, rather than via the optical fiber, from a second, pump laser. The interaction of the sample and the pump laser affect the optical properties of the sample. This change in optical properties can be detected by comparing the output signals from the measurement and reference arms.

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Cambiago, Italy

Angelo Barberis