RU92205U1 - INTEGRAL OPTICAL POLARIZATION SPLITTER - Google Patents

Abstract

An integrated optical polarization splitter based on a Mach-Zehnder microwave interferometer containing two directional couplers connected by the arms of the interferometer, characterized in that, in order to separate TE and TM polarized waveguide modes in optical information transmission and processing systems, mode anisotropy in one of the arms the interferometer was created by applying a buffer dielectric layer and a metal film over the waveguide, the device avoids the loss of optical radiation at ykovku waveguides with different refractive indices.

Description

The proposed device relates to optical polarizing elements. Known integrated optical splitter based on the Mach-Zehnder interferometer, in which the time delay of the optical signal when passing through the arms of the interferometer is polarization sensitive. One of the arms of the interferometer has pronounced mode birefringence. Silicon nitride is used as an anisotropic material that determines the polarization characteristics of the entire device, from which a part of the wave guide layer is formed in one of the arms. (Shani, Y. Four-port integrated optic polarization splitter [Text] / Y.Shani, C. Henry // Appl. Optics. - 1990. - Vol.29, No. 3. - P.337-339).

The disadvantage of this device is the use of a composite waveguide with different types of core materials, in the manufacture of which it is technologically difficult to obtain coordination of the propagation constants of the waveguide modes. In this splitter, in the event of a mismatch of the waveguide modes in the channels connected to each other, optical power losses occur and an incomplete transfer of energy from channel to channel is possible.

The aim of the proposed device is the separation of TE and TM polarized waveguide modes in optical systems for transmitting and processing information.

The goal is achieved by the fact that mode anisotropy is formed in one of the arms of the Mach-Zehnder integrated optical interferometer due to the deposition of a metal film and a dielectric buffer layer on the surface of the waveguide to organize the difference in the transit time of the TE modes and TM modes.

As a result of the mathematical analysis, it was proved that the proposed device allows you to spatially separate waveguide modes with orthogonal polarization.

Figure 1 shows the device polarization splitter for communication systems. The device contains a glass substrate on which is located the Mach-Zehnder microwave interferometer, consisting of input and output splitters and two arms of the same length. A buffer dielectric layer and a metal film are applied over one of the arms of the interferometer.

The device operates as follows. Optical radiation from the laser is introduced to the input of the interferometer, using an input splitter it is divided into two beams of the same intensity. Due to the deposition of a metal film, an anisotropic medium is formed in one of the arms of the interferometer in the waveguide, during which TE and TM polarized waves have different phase velocities. Anisotropy does not change the speed of the TE wave and its propagation time on both arms of the interferometer will be the same. A TM polarized wave in the arm of an interferometer with a metal film will propagate at a lower phase velocity. A metal film will inevitably absorb part of the radiation power, to avoid the absorption of TM polarized waves is possible only by introducing a buffer layer between the waveguide layer and the metal, as well as by varying the thickness of the metal film itself. At the output of the interferometer, the rays passing through the second splitter form an interference pattern, which will depend on the introduced phase shift. If the phase shift is 180 °, then all the power of the input signal will be output to the output port No. 1; if the phase shift is 0 °, then, on the contrary, the signal will be output through port number 2. The length of the metal film can be selected so that for TM waves the introduced phase shift between the waves at the output of the interferometer will be 180 °. For TE polarization, the phase shift between the waves at the output splitter will be 0 °. Thus, the TE wave and the TM wave will be separated at different output ports of the polarization splitter.

The implementation of a polarization splitter based on the plasma resonance effect allows controlling the phase velocity of TM polarized waves. The use of metal-dielectric channel waveguides in glass makes it possible to create a simple and effective integrated optical polarization splitter for the spatial separation of various polarization components of optical radiation.

Claims (1)

An integrated optical polarization splitter based on a Mach-Zehnder microwave interferometer containing two directional couplers connected by the arms of the interferometer, characterized in that, in order to separate TE and TM polarized waveguide modes in optical information transmission and processing systems, mode anisotropy in one of the arms the interferometer was created by applying a buffer dielectric layer and a metal film over the waveguide, the device avoids the loss of optical radiation at ykovku waveguides with different refractive indices.