arong Ji

High-contrast light-by-light switching and AND gate based on nonlinear photonic crystals

We present a light-by-light photonic crystal configuration consisting of a bend waveguide with three embedded Kerr-type nonlinear rods and a T-branch waveguide. We show that such a configuration can also demonstrate all-optical AND gate operation with extremely high-contrast between the OFF state and ON state in its transmission. Because the presented photonic crystal configuration of all-optical light-by-light switching is simple, this facilitates fabricating practical all-optical devices and further large-scale optical integration.

Small-signal analysis of bidirectional operating characteristics in a Raman ring laser with external optical injections

Employing the small-signal analysis, we study the bidirectional operating characteristics in a Raman ring laser. Bidirectional operation is found not stable in a silicon ring because of the existence of two-photon absorption. Using polar crystals which have different forward and backward Raman gain or introducing external optical injections helps to establish stable bidirectional operation in a Raman ring laser.

Optimization for the high-Q monopole mode in electrically driven single-cell photonic crystal laser cavity

Using 3D finite-difference time-domain calculations, we investigated the monopole mode in an electrically driven single-cell photonic crystal laser cavity with the introduction of a small central post as an electrical contact and heat-flow path. We demonstrate that the high-Q factor and large Purcell factor can be obtained by modifying the cavity.

Mapping the Effective Stimulated Raman Nonlinearity in Submicrometer Silicon Waveguides

Stimulated Raman scattering (SRS) with the effect of large longitudinal electric field (Ez) that appears in submicrometer waveguide (SMWG) is studied. Because of the existence of large Ez, SRS is allowed even its pump-Stokes polarization combination seems to be forbidden by the Raman selection rules. It also suggests that SRS is quite weak in extremely small SMWG because the mode distributes a large part outside the waveguide core region which has no contribution to SRS. Based on its stronger Raman gain and better performance in single mode property and free carrier lifetime reduction, the ridge waveguide is a better candidate than wire one to realize SRS lasing in extremely small SMWG.

Brillouin/Raman compensation of the Kerr-effect-induced bias in a nonlinear ring laser gyroscope

In this Letter, the beat frequency at rest of a ring laser gyroscope with nonlinear effects is discussed in detail. Even without an additional intensity-stabilizing system, the random nullshift bias induced by the Kerr effect is compensated by the phase shift associated with the stimulated Brillouin/Raman scattering. And the nonlinear stimulated scattering also serves as the gain mechanism of the gyroscope. And thus the influence of the fluctuation of the injected pump intensity on the beat frequency is eliminated.

Complete optical on-chip isolation based on asymmetric stimulated Raman gain/loss

In this Letter, we suggest an on-chip integrated isolator based on an add-drop filter with unidirectional Raman-induced gain (or loss). For the steady state, complete one-way propagation for monochromatic signals is realized in the bus waveguide. For transient transmission, the burr is suppressed. And the power consumption is reduced by enhancing the Q factor of the resonator at the control frequency.

Mapping the modal effective area in submicrometer strip and slot waveguides

In this paper, the relationship between the nonlinear effect and the cross-section of the waveguide is studied by computing the modal effective area. And the structure of both wire and slot waveguide are optimized to enhance the nonlinear effect in waveguide core and cover. It is found out that the slot waveguide is a better candidate to take advantage of the nonlinear effect in the cover material and the optimized slot thickness is about 20nm to get the strongest nonlinear gain in slot.