High-linearity modulation chip and method based on dual-output silicon-based series push-pull Mach-Zehnder modulator

Abstract

The invention discloses a high-linearity modulation chip and method based on a dual-output silicon-based series push-pull Mach-Zehnder modulator. According to the invention, a dual-output silicon-based carrier depletion mode modulator is designed, and the silicon-based modulator is arranged at a minimum working point. The optical power input by a laser is divided into two paths through an on-chip optical power divider, one path of optical signal serves as an optical carrier and is modulated by an electric signal through a silicon-based modulator, and the other path of optical signal serves as an optical local oscillation signal and is used for compensating and suppressing modulation nonlinearity in the modulated optical signal. Finally, two paths of complementary output optical signals and optical local oscillation signals of the silicon-based modulator are combined through two silicon-based multimode interferometers, so that the third-order electro-optical nonlinearity of the modulator is suppressed. Meanwhile, a 3dB optical power divider and a silicon optical delay waveguide with a specific length are integrated on a chip, and a receiving end can suppress second-order nonlinearity with a specific frequency by using a balance detector, so that high-linearity modulation of the silicon-based modulator is realized.

Description

technical field [0001] The present invention relates to a high linear modulation method based on Dual-outputSeries Push-pull Silicon-based Mach-Zehnder Modulator (DSP Si-MZM), in particular to a method including adjustable Series push-pull silicon-based carrier-depletion Mach-Zehnder modulator with split ratio optical power splitter. Background technique [0002] No matter in analog optical link or digital optical communication, modulators, such as Mach-Zehnder Modulators (MZM), Microring Modulators (Ring Modulator, RM), etc., are required to modulate microwave signals. to the optical carrier for transmission. In the process of electro-optic and photoelectric conversion, there is a very important factor affecting the dynamic range of the link - nonlinear distortion, which includes harmonic distortion and alternating signal distortion. In order to achieve high-fidelity transmission in analog or digital optical communication links, the above optical transmission links need t...

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Problems solved by technology

Research at home and abroad has proposed a variety of solutions for the linearization of Si-MZM, for example, by changing the doping concentration of the modulation arm in the silicon-based modulator to change the overlapping area of ​​the optical field and the electric field to achieve a high linear link; The optical nonlinear DC-Kerr effect is used to compensate the nonlinearity of carriers and sinusoidal modulation curves in silicon-based modulators, but these two methods change the process flow of chip foundries and increase the complexity and cost of chip processing

In addition, imitating the realization principle of the lithium niobate high linearity modulator with parallel MZM structure, it is also possible to achieve silicon-based high linearity by adjusting the optical power distribution ratio of silicon-based parallel MZM, the bias operating point, and the optical power distribution ratio of modulated small signals. Modulator, but this method has higher operational complexity and more monitoring and control variables

In addition, the method described above only focuses on the distortion of the third-order harmonic / intermodulation signal generated by the modulator, and does not consider the impact of the second harmonic / intermodulation signal on the dynamic range of the link at high octave frequency

[0005] The structure of a single Si-MZM is simple, but there is no similar report on optical domain linearization based on a single Si-MZM. also not reported in

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