Instantaneous frequency measurement system and method based on differential optical time stretching principle

[0024] Embodiment 1: The instantaneous frequency measurement method based on the principle of differential optical time stretching, by adopting a dual-output push-pull Mach-Zehnder modulator (DOMZM) with complementary outputs and a balanced photodetector to realize differential detection, suppressing due to laser spectrum The RF signal distortion caused by unevenness, the RF signal to be tested is firstly modulated onto the chirped pulse light, and then linearly widened in the time domain by the dispersion module, so that the analog bandwidth is compressed, and the high-speed signal can be realized with a low-speed digitizer quantized sampling.

[0025] Contains the following steps:

[0026] When the DOMZM is at the quadrature bias point, assuming the RF input signal is V(t), the output electric fields of the two complementary output terminals of the DOMZM can be expressed as:

[0027]

[0028] Among them, E 0 (t) represents the input optical signal, V π is the half-wave vo

[0046] Embodiment 2: the instantaneous frequency measurement system based on the principle of differential optical time stretching, such as figure 1 As shown, it includes pulsed laser source 1, dispersion module 1 2, polarization controller 3, DOMZM 4, optical circulator 1 5 and optical circulator 2 6, dispersion module 2 7, balance detector 8 and real-time oscilloscope 9 .

[0047] The central wavelength of the light pulse output by the light source 1 used in this embodiment is 1565 nm, the laser pulse width is about 100 fs, the 3 dB bandwidth is 23 nm, and the repetition frequency is 100 MHz. The dispersion values ​​of the first dispersion module 2 and the second dispersion module 7 are -20 ps / nm and -150 ps / nm respectively, so according to the formula (5), the stretching factor of the system is 8.5. DOMZM 4 has a bandwidth of 20GHz, V π is 4.7V, the bandwidth of the balanced photodetector 8 is 10GHz, the bandwidth of the real-time oscilloscope 9 is 6GHz, and the sampling