Xiao-shi Song

Polarization independent quasi-phase-matched sum frequency generation for single photon detection

Polarization independent sum frequency generation (SFG) is proposed in an electro-optic (EO) tunable periodically poled Lithium Niobate (PPLN). The PPLN consists of four sections. External electric field could be selectively applied to them to induce polarization rotation between the ordinary and extraordinary waves. If the domain structure is well designed, the signal wave with an arbitrary polarization state could realize efficient frequency up-conversion as long as a z-polarized pump wave is selected. The applications in single photon detection and optical communications are discussed.

Tunable broadband isolator based on electro-optically induced linear gratings in a nonlinear photonic crystal

We theoretically propose a broadband optical isolator based on second-harmonic generation in a one-dimensional quadratic nonlinear photonic crystal (NPC) with an embedded defect. An external electric field along the z axis is applied to modulate the NPC refractive index periodically. Complete optical isolation always could be reached with the help of an external field. Influences of the defect position and thickness are discussed. The spectral and power tolerances of the isolator also have been investigated and show high contrast within a wide wavelength range at different power levels.

Optical parametric amplification of arbitrarily polarized light in periodically poled LiNbO 3

Optical parametric amplification (OPA) of arbitrarily polarized light is proposed in a multi-section periodically poled Lithium Niobate (PPLN). External electric field is applied on selected sections to induce the polarization rotation of involved lights, thus the quasi-phase matched optical parametric processes exhibit polarization insensitivity under suitable voltage. In addition to the amplified signal wave, an idler wave with the same polarization is generated simultaneously. As an example, a ~10 times OPA showing polarization independency is simulated. Applications of this technology are also discussed.

Electromagnetically induced transparency-like transmission in periodically poled lithium niobate with a defect

Electromagnetically induced transparency (EIT)-like transmission is observed in an electro-optic (EO) tunable periodically poled lithium niobate (PPLN) with a central defect. When an electric field is applied, light satisfying the phase matching condition keeps its original polarization, although it experiences polarization rotation then turns back. Therefore the corresponding light always may pass though freely but with an EO tunable phase and dispersion. On the other hand, light with a neighboring wavelength is blocked. An EIT-like spectrum is thus obtained with tunable group delay. A low-voltage bulk phase shifter with over two orders of magnitude larger index change is obtained.

POLARIZATION INSENSITIVE QUASI-PHASE-MATCHED SECOND HARMONIC GENERATION

Polarization insensitive second harmonic generation (SHG) is proposed in an electro-optic (EO) tunable periodically poled Lithium Niobate (PPLN). The PPLN consists of four sections. External electric fields could be selectively applied to them to induce polarization rotation between the ordinary and extraordinary waves. If the domain structure is well-designed, the fundamental wave with an arbitrary polarization state can be frequency doubled efficiently in this special PPLN.

Polarization independent optical parametric amplification in periodically poled LiNbO3

We propose a scheme to realize arbitrarily polarized light optical parametric amplification in a periodically poled Lithium Niobate using quasi-phase matching. The domain structure should be well-designed with suitable electric field applied on selected sections.

Defect induced EIT — Like spectrum and tunable group delay in periodically poled LiNbO 3

Electromagnetically induced transparency - Like spectrum with tunable group delay is observed in a periodically poled LiNbO3 with a central defect when an electric field is applied. A low voltage bulk phase shifter is obtained.