Heming Chen

Optically-controlled high-speed terahertz wave modulator based on nonlinear photonic crystals.

An optically-controlled terahertz (THz) modulator based on nonlinear photonic crystals (PCs) is proposed, which has the merits of high speed, compactness and easy integration. The PC structure consists of point and line defects. High speed modulation of THz wave can be realized by filling one of the point defects with organic polymer polyaniline which has rapid nonlinear response time. Simulation results show that the modulation rate, modulation depth and insertion loss of the modulator achieve 2.5 GHz, 20.3 dB and 1.02 dB, respectively.

Design of a DWDM Multi/Demultiplexer Based on 2-D Photonic Crystals

A multiplexer and demultiplexer (MUX/DEMUX) based on 2-D photonic crystals (PhCs) for a dense wavelength division multiplexing (DWDM) system is presented. The designed MUX/DEMUX consists of narrow bandpass filters and magneto-optical circulators based on 2-D PhCs with triangular lattice of air holes, the parameters of which are analyzed by a finite element method. The simulation results show that the frequencies 193.4, 193.3, and 193.2 THz could be multi/demultiplexed with a low insertion loss (<;0.5 dB) and large channel isolation (>18.4 dB). The proposed DWDM MUX/DEMUX could be used to provide transport solution for DWDM optical communication system with 100-GHz spacing.

Multi/demulti-plexer based on transverse mode conversion in photonic crystal waveguides

A novel mode multiplexer and demultiplexer (MMUX/DEMMUX) based on 2-D photonic crystal (PC) at 1550 nm is proposed. The PC-based mode MMUX/DEMMUX including mode conversion function with a single-mode and multi-mode waveguides can be realized by quasi phase-matching TE(0) & TE(1) modes of two waveguides. 2DFinite-Difference-Time-Domain and beam propagation methods are used for simulation. The results show that PC-based mode MMUX/DEMMUX has the potential for high-capacity MDM optical communication systems with a low insertion loss (<0.36dB), low mode crosstalk (< -20.9 dB) and wide bandwidth (~100 nm).

A hybrid multiplexer for wavelength/mode-division based on photonic crystals

A hybrid multiplexer (HMUX) for wavelength/mode-division (WDM/MDM) based on photonic crystals (PCs) is proposed. The device can realize TE0 and TE1 modes multiplexing at wavelengths of 1550nm and 1570nm. According to quasi phase matching, a structure with an asymmetrical parallel waveguide (APW) was used to achieve mode conversion. The transmittance of the TE0 mode at wavelengths of 1550nm and 1570nm are 98.4% and 96.3%, the corresponding insertion loss are 0.07dB and 0.16dB respectively. The crosstalk of the TE0 mode at wavelengths of 1550nm and 1570nm are -27.66dB and -27.32dB respectively. The transmittance of the TE1 mode at wavelengths of 1550nm and 1570nm are 95.8% and 93.9%, the corresponding insertion loss are 0.19dB and 0.27dB respectively. The crosstalk of the TE1 mode at wavelengths of 1550nm and 1570nm are -38.73dB and -38.9dB respectively. The PC-based HMUX has great performance, and it will have great application potential in future ultrahigh-speed and large-capacity communication systems.

A hybrid multiplexer/de-multiplexer for wavelength-mode-division based on photonic crystals

Abstract A hybrid multiplexer/de-multiplexer (HMUX/HDeMUX) for wavelength-mode-division based on photonic crystals (PCs) is presented. The proposed device consists of a point-defect cavity, a wavelength-selective cavity and asymmetrical parallel waveguides. Coupled-mode theory (CMT) is applied to the analysis, and the finite-difference time-domain (FDTD) method is used for the simulations. The simulation results show that the device can multiplex the fundamental and first-order modes of 1550 and 1310 nm. It exhibits not only a low insertion loss (<0.37 dB) but also low mode crosstalk (<−13 dB). Thus, the PC-based HMUX/HDeMUX has considerable potential for application in large-capacity optical communication systems.