Microwave source phase noise measuring device based on bidirectional optical phase modulator

Abstract

The invention discloses a microwave source phase noise measuring device based on a bidirectional optical phase modulator, which comprises a microwave power divider, a laser, an optical circulator, a first branch, a second branch, an optical coupler, a photoelectric detector and a signal analysis device. A bidirectional optical phase modulator, a first fiber bragg grating and a single-mode fiber are sequentially arranged in the first branch, a second fiber bragg grating and an adjustable optical delay line are sequentially arranged in the second branch, the optical circulator is provided with three ports, and the three ports are respectively connected with the laser, the bidirectional optical phase modulator and the second fiber bragg grating. According to the invention, the single bidirectional optical phase modulator is utilized to realize a full-optical-domain frequency mixing function, so that the use of an electric frequency mixer is avoided, and the use of active devices such as a microwave amplifier is reduced. The device has the advantages of simple structure, low cost, large working bandwidth and flat response, the noise floor of the phase noise measuring system is reduced, and the measuring precision and sensitivity are improved.

Description

technical field [0001] The invention relates to the technical field of phase noise measurement, in particular to a microwave source phase noise measurement device based on a bidirectional optical phase modulator. Background technique [0002] With the continuous development of microwave oscillator technology, especially the emergence of photoelectric oscillators that can directly generate ultra-high frequency and ultra-low phase noise microwave signals, it poses a great challenge to the existing phase noise measurement technology. The frequency discrimination method based on optical delay line is a method with great potential for phase noise measurement of microwave sources. This method can achieve high phase noise measurement sensitivity with the help of long delay provided by low-loss optical fiber. However, in this scheme, the operating bandwidth is usually limited by electronic devices such as electric phase shifters, electric amplifiers, and electric mixers, and before ...

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Problems solved by technology

However, the use of cascaded modulators increases the cost and complexity of the system, and leads to large insertion loss, which reduces the conversion efficiency of the system

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