Optimization of MMI-WDM demultiplexer by using BPM method

Abstract

An optical demultiplexer based on the multimode interference (MMI) coupler is demonstrated in this work. The proposed device is designed and simulated by showing the optimum parameters for the structure (length of MMI region, the separation and the angle of the arm). The calculated results show that the crosstalk of the coupler is about -19.4 and -11.66 dB for 1310 and 1550 nm respectively. The insertion Loss is around 1.5-2.5 dB for demultiplexing operation. Keywords: optical coupler, optical telecommunication, optical crosstalk, beam propagation method (BPM), multimode interference (MMI), wavelength division multiplexing (WDM). INTRODUCTIONIntensive research has recently been conducted on semiconductor optical devices for wavelength division multiplexers as reported in literatures. Wavelength division multiplexing (WDM) devices for subscriber networks have become an important issue. Moreover, the integration of optical element devices with wavelength selective functions has also attracted a lot of attention. Several wavelength division devices have been demonstrated using Bragg gratings, liquid crystal filters, fiber ring filters, MEMS systems and other methods. One promising technique is using silicon-on-insulator waveguide devices in WDM optical communication systems. CMOS electronics on SOI wafers have shown promise as the future technology for low-power and high-speed applications. Although Bragg gratings, liquid crystals and MEMS are candidates, the multimode interference (MMI) WDM device has a smaller size and is compatible with the CMOS fabrication process. Some good SOI waveguide structures have also been proved for reducing the optical insertion loss and optical crosstalk in 1300 and 1550 nm optical communication windows. For the above reasons, we choose the SOI structure for producing wavelength division devices [1].Recently, some good WDM applications using MMI waveguide structure were reported. Therefore, we apply the MMI technique to realize a 1×2 compact MMI SOI 1310/1550 nm wavelength division multiplexer that is smaller than the traditional fiber-optic 1310/1550 nm wavelength division multiplexer. Meanwhile, integration of hybrid photonic devices is becoming an important issue for applications in optical communication networks. We think that a compact MMI wavelength division multiplexer is very useful in hybrid photonic device integration [6].Couplers play an important role in optical communication systems and can be used to combine or split the power of different optical channels. Single-mode fiber couplers are also used to make optical fiber WDM components, such as 1310/1550 nm WDM fiber-optic directional couplers. The fiber-optical directional couplers have a large coupling length (about several centimetres) [3], [4].In this paper, we design and simulate the wavelength response of MMI wavelength division multiplexers. Our simulation is based on the method of BPM (beam propagation method). We search the critical parameters (length of MMI, the separation and the arm angle) which give the optimu...

Mitigation of photon background in nanoplasmonic all-on-chip Raman sensors

“…For instance, the reflection due to the plasmonic waveguide could be better controlled by a more precise deposition technique such as the atomic layer deposition of gold that furthermore results in an increased Raman response [27]. Another way to improve the architecture is to engineer the MMI so that it acts as a wavelength division multiplexer [28,29] transmitting the excitation beam from a port 1 to 3 with a high transmission and transmitting it inefficiently from port 3 to port 2 while the scattered Raman light is collected in port 3. This would lead to a reduction of the reflected pump light in the output waveguide therefore improving the SBR for even longer/more complex analyzing circuits.…”