The indicators of the Mach-Zehnder modulator

The indicators of the Mach-Zehnder modulator

The Mach-Zehnder Modulator (abbreviated as MZM modulator) is a key device used to achieve optical signal modulation in the field of optical communication. It is an important component of Electro-Optic Modulator, and its performance indicators directly affect the transmission efficiency and stability of communication systems. The following is an introduction to its main indicators:

Optical parameters

1. 3dB bandwidth: It refers to the frequency range when the amplitude of the modulator’s output signal drops by 3dB, with the unit being GHz. The higher the bandwidth, the higher the supported signal transmission rate. For example, a 90GHz bandwidth can support 200Gbps PAM4 signal transmission.

2. Extinction ratio (ER) : The ratio of the maximum output optical power to the minimum optical power, with the unit of dB. The higher the extinction ratio, the more distinct the distinction between “0″ and “1″ in the signal, and the stronger the anti-noise capability.

3. Insertion loss: The optical power loss introduced by the modulator, with the unit of dB. The lower the insertion loss, the higher the overall efficiency of the system.

4. Return loss: The ratio of the reflected optical power at the input end to the input optical power, with the unit of dB. High return loss can reduce the impact of reflected light on the system.

Electrical parameters

Half-wave voltage (Vπ) : The voltage required to generate a 180° phase difference in the output optical signal of the modulator, measured in V. The lower the Vπ, the smaller the drive voltage requirement and the lower the power consumption.

2. VπL value: The product of the half-wave voltage and the modulator length, reflecting the modulation efficiency. For instance, VπL = 2.2V·cm (L=2.58mm) represents the modulation voltage required at a specific length.

3. Dc bias voltage: It is used to stabilize the operating point of the modulator and prevent bias drift caused by factors such as temperature and vibration.

Other key indicators

1. Data rate: For instance, the 200Gbps PAM4 signal transmission capability reflects the high-speed communication capability supported by the modulator.

2. TDECQ value: An indicator for measuring the quality of modulated signals, with the unit being dB. The higher the TDECQ value, the stronger the signal’s anti-noise ability and the lower the bit error rate.

Summary: The performance of a March-Zendl modulator is comprehensively determined by indicators such as optical bandwidth, extinction ratio, insertion loss, and half-wave voltage. High bandwidth, low insertion loss, high extinction ratio and low Vπ are the key features of high-performance modulators, which directly affect the transmission rate, stability and energy consumption of optical communication systems.