All-optically linearized silicon modulator with ultrahigh SFDR of 131  dB · Hz^6/7

Integrated high-linearity modulators are crucial for high dynamic-range microwave photonic (MWP) systems. Conventional linearization schemes usually involve the fine tuning of radio-frequency (RF) power distribution, which is rather inconvenient for practical applications and can hardly be implemented on the integrated photonics chip. In this paper, we propose an elegant scheme to linearize a silicon-based modulator in which the active tuning of RF power is eliminated. The device consists of two carrier-depletion-based Mach–Zehnder modulators (MZMs), which are connected in series by a 1×2 thermal optical switch (OS). The OS is used to adjust the ratio between the modulation depths of the two sub-MZMs. Under a proper ratio, the complementary third-order intermodulation distortion (IMD3) of the two sub-MZMs can effectively cancel each other out. The measured spurious-free dynamic ranges for IMD3 are 131, 127, 118, 110, and 109 dB · Hz 6/7 at frequencies of 1, 10, 20, 30, and 40 GHz, respectively, which represent the highest linearities ever reached by the integrated modulator chips on all available material platforms.