Two-dimensional grating coupling-based silicon-based QPSK (Quadrature Phase Shift Keying) photomodulator

Abstract

The invention discloses a two-dimensional grating coupling-based silicon-based QPSK (Quadrature Phase Shift Keying) photomodulator, comprising a two-dimensional grating coupler, four mode transducers, a single-mode waveguide, an optical cross and four radio frequency phase shifters, wherein the two-dimensional grating coupler, serving as a vertical optical coupling interface and a four-channel powder divider, averagely splits a coupling light into four channel waveguides; the four mode transducers are used for carrying out mode conversion and insulated optical transmission between the two-dimensional grating and the single-mode waveguide; the single-mode waveguide is used for carrying out low-loss single-mode transmission of an optical signal; the optical cross is used for carrying out non-crosstalk low-loss optical cross transmission between two waveguides; the four radio frequency phase shifters are used for loading electric signals of in-phase road data DATAI and quadrature road data DATAQ, thus achieving BPSK (Binary Phase Shift Keying) light phase modulation of two roads. Two of three MMI beam combiners are applied to light beam combination of two branch circuits in the in-phase road and the quadrature road; the other MMI beam combiner is applied to light beam combination of the in-phase road and the quadrature road; two thermal optical phase shifters are used for adjusting an optical wave phase difference between the in-phase road and the quadrature road by direct current, so as to meet pi / 2, and thus the optical signals of the in-phase road and the quadrature road are synthesized into a QPSK modulation signal.

Description

technical field [0001] The invention relates to silicon-based photonics and chip-level optical interconnection technology, in particular to a silicon-based QPSK optical modulator based on two-dimensional grating coupling. Background technique [0002] In the modern society with the rapid development of science and technology, a large amount of information and data exchange requires a high-speed, broadband communication system. Theoretical calculations show that increasing the carrier frequency can increase the frequency bandwidth and thus expand the capacity of the communication system. When an electrical signal is transmitted on a conductor, the impedance and parasitic capacitance of the conductor will increase as the frequency increases, causing the electrical signal to attenuate rapidly. Even if a coaxial cable with low high-frequency loss is used, the loss has reached 5dB / Km at a frequency of 100MHz. Therefore, the cable is only suitable for short-distance and low-freq...

AI Technical Summary

Problems solved by technology

Nevertheless, the performance of silicon-based modulators is generally inferior to that of commercial lithium niobate modulators due to the electro-optic effect of weak plasmonic dispersion used in silicon-based modulation

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