Silicon photonic free-space beam steered optical switch using wavelength tuned nanoantennas

Abstract

As optical interconnects data rates increases, the Opto–Electro–Optical (OEO) conversion in the ports of the traditional electronic packet switches (EPS) will not be an acceptable solution anymore because of lack of scalability, high cost and excess losses [9]. High speed and scalable optical switches could replace EPS and completely eliminate the need for the OEO conversion. Free–Space Optical (FSO) switches such as Micro ElectroMechanical System switches (MEMS) have high scalability but low switching speed [2]. Whereas, photonic integrated circuit (PIC) switches have shown high switching speed which ranges from some nanoseconds to 10s of microseconds but low scalability with up to 32 ports [6]. The perfect switch would combine the high scalability and high switching speed of the FSO and PIC switches, respectively. In this communication, a novel PIC switch architecture is presented to use grating couplers and their ability to diffract light to the free space. Grating couplers are facing each other and are used as transmitting and receiving nanoantennas. The switch has one input transmitting and four output receiving nanoantennas. The angle of emission of the diffracted beam depends on the wavelength which ranges from 1.3 to 1.55μm. Tuning the wavelength, the beam is steered to one of the receiving nanoantennas. The results monitoring the nanoantennas S parameters reveal satisfactory coupling between the input and output ports with insertion losses in the range between -6 to -8dB, while the interchannel crosstalk isolation from the other ports is less than -9dB from the value of coupling.