Double-polarization fiber ring interferometer based on a single-mode isotropic fiber for gyroscopy

We propose and implement the scheme of a whole-fiber double-polarization ring interferometer based on an isotropic fiber for gyroscopy purposes. The results of an experimental study of the output signal of the interferometer based on the proposed scheme are presented. The shift of the zero point of the interferometer signal (at a level of 3°/h) and the drift of the zero point (at a level of 1°/h) are determined. The rotation sensitivity of the interferometer is measured. It amounts to 0.1°/h, which agrees well with the calculation allowing for the shot noise of the photoelectric current at the output of the scheme. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 4, pp. 328–332, April 2008.     

New Approaches in Broadband Fiber-Optical Interferometry for Optical Coherent Tomography

We have developed new methods of IR ultrabroadband interferometry for increasing the limiting capabilities of optical coherent tomography (OCT). In particular, this permitted us to create an optical coherent microscope combining the principles of confocal microscopy and OCT. To increase the longitudinal resolution, we synthesized an ultrabroadband optical spectrum based on two superluminescent diodes with separated radiation spectra. The resulting longitudinal resolution was 3.4 m and the transverse resolution was 3.9 m. Images of the inner structure of biological tissues are obtained at the cellular level. Experimental results of a study of biological tissue by the cross-polarization OCT are described.     

Linear-wavenumber spectrometer for high-speed spectral-domain optical coherence tomography

An equidistant (in the wavenumber) spectrometer based on a diffraction grating, a compensation prism, and a CCD linear array is developed and implemented for spectral-domain optical coherence tomography. A criterion is introduced for estimating the level of residual nonequidistance. This criterion allows one to determine the threshold compensation level necessary for obtaining the spectrally limited spatial resolution. The method is tested in spectral-domain optical coherent tomography systems at wavelengths of 1270 and 830 nm.

     

Measurement of nanoangström oscillatory displacements by a gas laser with a small natural linewidth

Radiophysics and Quantum Electronics - A new He-Ne laser (0.63 μm) with a wide region of single-mode oscillation (2 GHz) obtained by selection of longitudinal modes with the use of an...     

Suppression of image artifacts in the spectral-domain optical coherence tomography

In this paper, we review methods for obtaining in vivo optical images of bio-objects with the resolution ranged from several units to tens of micrometers, namely, the methods of spectral-domain optical coherence tomography. We focus on problems that are specific of the spectral-domain optical coherence tomography, namely, the presence of coherent noise and mirror-symmetric phantoms in the image. On the basis of the most important relevant publications, we analyze possibilities of eliminating these drawbacks in modern devices.     

Measurement of optical fiber birefringence with a wide-band radiation source

Applied Physics Institute, Academy of Sciences of the USSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 6, pp. 717–720, June, 1991.     

All-fiber optical gyroscopes on orthogonal polarizations

The expressions for the nonreciprocal phase at the output of a fiber ring interferometer (FRI) related to polarization phenomena are obtained in the general form. These expressions are used to analyze two systems of the FRIs on anisotropic elements without polarizer with one and two beam splitters with allowance for their phase anisotropy and losses. We formulate the requirements on the elements of circuits and their adjustment, which lead to minimization of the nonreciprocal polarization phase due to the single-loop realization of two independent orthogonal gyroscopic channels whose signals are added at the output. This allows us to use the above simple circuits for creating moderate-accuracy fiber gyroscopes. Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 11, pp. 1448–1460, November, 1998.