Optic-microwave frequency discriminator for laser frequency difference locking, and method thereof

摘要

An optic-microwave frequency discriminator includes: a fiber coupler receives and combines a first laser and a second laser, than the fiber coupler respectively generates and outputs a first light signal and a second light signal; a photodiode module respectively receives the first light signal and the second light signal, and converts the first light signal into a first microwave signal and converts the second light signal into a second microwave signal; a microwave phase shifter generates a shifted microwave signal by introducing a phase shift to the second microwave signal; a 90° microwave bridge combines the first microwave signal and the shifted microwave signal for generating a first bridge signal and a second bridge signal; a normalized balanced detection module generates an error signal; and a control module generates a controlling voltage signal according to the error signal for tuning a frequency of the second laser.

主权项

1. An optic-microwave frequency discriminator for laser frequency difference locking, comprising:
a fiber coupler, wherein the fiber coupler receives and combines a first laser from a first laser device and a second laser from a second laser device, the fiber coupler respectively generates and outputs a first light signal and a second light signal, which are identical, through a first fiber coupler output terminal and a second fiber coupler output terminal; a photodiode module respectively communicating with the first fiber coupler output terminal and the second fiber coupler output terminal, so as to receive the first light signal and the second light signal, wherein the photodiode module converts the first light signal into a first microwave signal and converts the second light signal into a second microwave signal; wherein the photodiode module comprises a first photodiode output terminal and a second photodiode output terminal, the first microwave signal and the second microwave signal are respectively outputted through the first photodiode output terminal and the second photodiode output terminal; a microwave phase shifter communicating with the second photodiode output terminal, so as to receive the second microwave signal, generate a shifted microwave signal by introducing a phase shift to the second microwave signal, and output the shifted microwave signal; a 90° microwave bridge comprising a first bridge input terminal, a second bridge input terminal, a first bridge output terminal and a second bridge output terminal, wherein the first bridge input terminal communicates with the first photodiode output terminal for receiving the first microwave signal, the second bridge input terminal communicates with the microwave phase shifter for receiving the shifted microwave signal; the 90° microwave bridge combines the first microwave signal and the shifted microwave signal for generating a first bridge signal which is outputted through the first bridge output terminal, and generating a second bridge signal which is outputted through the second bridge output terminal; a normalized balanced detection module, which respectively communicates with the first bridge output terminal and the second bridge output terminal for receiving the first bridge signal and the second bridge signal, wherein the normalized balanced detection module calculates the first bridge signal and the second bridge signal for generating and outputting an error signal; and a control module communicating with the normalized balanced detection module for receiving the error signal, wherein the control module generates a controlling voltage signal according to the error signal, and sends the controlling voltage to the second laser device for tuning a frequency of the second laser; the control module also sends the controlling voltage to the microwave phase shifter for adjusting the phase shift.