Polarization rotating device

A method, which comprises receiving TM polarized light, and converting the TM polarized light into TE polarized light by using a polarization rotating device an operating wavelength,

• the polarization rotating device comprising a waveguide formed of a crystalline material layer,
• the waveguide comprising:
• an input portion,
• a first mode evolution portion to receive TM polarized light from the input portion, and to transform the received TM polarized light into light of a tilted polarization mode by mode evolution,
• a second mode evolution portion to receive the light of the tilted polarization mode from the first mode evolution portion, and to transform the received light of the tilted polarization mode into TE polarized light by mode evolution,
• an output portion to output the TE polarized light received from the second mode evolution portion,
• wherein the first mode evolution portion comprises a first tapered inclined facet, which defines polygonal cross-sectional shapes together with horizontal and vertical surfaces of the first mode evolution portion, wherein the width of the first tapered inclined facet increases with increasing distance from the input portion, wherein the second mode evolution portion comprises a second tapered inclined facet, which defines polygonal cross-sectional shapes together with horizontal and vertical surfaces of the second mode evolution portion, wherein the width of the second tapered inclined facet decreases with increasing distance from the input portion, wherein the expanding tapered inclined facet and the converging tapered inclined facet are portions of the same inclined crystal plane of the crystalline material layer, wherein the width and the height of the input portion have been selected such that the polarization rotating device enables multimode operation at at least one operating wavelength of the device.

A method, which comprises receiving TE polarized light, and converting the TE polarized light into TM polarized light by using a polarization rotating device at the operating wavelength.

• the polarization rotating device comprising a waveguide formed of a crystalline material layer,
• the waveguide comprising:
• an input portion,
• a first mode evolution portion to receive TM polarized light from the input portion, and to transform the received TM polarized light into light of a tilted polarization mode by mode evolution,
• a second mode evolution portion to receive the light of the tilted polarization mode from the first mode evolution portion, and to transform the received light of the tilted polarization mode into TE polarized light by mode evolution,
• an output portion to output the TE polarized light received from the second mode evolution portion,
• wherein the first mode evolution portion comprises a first tapered inclined facet, which defines polygonal cross-sectional shapes together with horizontal and vertical surfaces of the first mode evolution portion, wherein the width of the first tapered inclined facet increases with increasing distance from the input portion, wherein the second mode evolution portion comprises a second tapered inclined facet, which defines polygonal cross-sectional shapes together with horizontal and vertical surfaces of the second mode evolution portion, wherein the width of the second tapered inclined facet decreases with increasing distance from the input portion, wherein the expanding tapered inclined facet and the converging tapered inclined facet are portions of the same inclined crystal plane of the crystalline material layer, wherein the width and the height of the input portion have been selected such that the polarization rotating device enables multimode operation at at least one operating wavelength of the device.

A method for producing a polarization rotating device,

• the method comprising:
• providing a layer of crystalline material,
• forming an inclined facet on the crystalline material by first wet etching such that an angle between the inclined facet and a bottom surface of the layer is equal to 54.7°, and
• producing the polarization rotating device from the crystalline material layer by second etching,
• the polarization rotating device comprising a waveguide formed of a crystalline material layer,
• the waveguide comprising:
• an input portion,
• a first mode evolution portion to receive TM polarized light from the input portion, and to transform the received TM polarized light into light of a tilted polarization mode by mode evolution,
• a second mode evolution portion to receive the light of the tilted polarization mode from the first mode evolution portion, and to transform the received light of the tilted polarization mode into TE polarized light by mode evolution,
• an output portion to output the TE polarized light received from the second mode evolution portion,
• wherein the first mode evolution portion comprises a first tapered inclined facet, which defines polygonal cross-sectional shapes together with horizontal and vertical surfaces of the first mode evolution portion, wherein the width of the first tapered inclined facet increases with increasing distance from the input portion, wherein the second mode evolution portion comprises a second tapered inclined facet, which defines polygonal cross-sectional shapes together with horizontal and vertical surfaces of the second mode evolution portion, wherein the width of the second tapered inclined facet decreases with increasing distance from the input portion, wherein the expanding tapered inclined facet and the converging tapered inclined facet are portions of the same inclined crystal plane of the crystalline material layer, wherein the width and the height of the input portion have been selected such that the polarization rotating device enables multimode operation at at least one operating wavelength of the device.