【Objective】

2

High-frequency microwave carriers (GHz) with tunable capability have a wide range of applications in 5th Generation Mobile Communication Technology (5G)/ 6th Generation Mobile Communication Technology (6G) wireless networks

radar systems

and satellite communications. Due to the relatively simple structure of the system

the large bandwidth and the low loss

the technical scheme of generating high-frequency tunable microwave carriers based on photonic technology has attracted extensive attention from domestic and international research teams. Current photogenerated microwave experiments are mostly conducted in C-band wavelengths because of the mature commercial devices. Meanwhile

the Wavelength Division Multiplexing (WDM)-Radio Over Fiber (ROF) technology integrates the WDM technology with the ROF technology so as to flexibly realize the combining/splitting of microwave bands with the help of the combining/splitting of WDM system in the optical frequency domain. The ROF part of the system employs photogenerated microwave technology to simplify the base station configuration. Constrained by the limited bandwidth resources in the C-band wavelengths(35 nm

1 530~1 565 nm)

there is a drive for the generation of microwave to expand to wider spectral ranges. The U-band wavelengths can also provide channel bandwidths as wide as 50 nm (1 625~1 675 nm) to alleviate the channel utilization pressure in the C-band wavelengths; In the U-band wavelengths

Standard Single Mode Fibers(SSMFs) have achieved optical power loss as low as 0.195 dB/km (@1 625 nm); In particular

thulium-doped fiber amplifiers have also demonstrated a large bandwidth gain of 18.7 dB (@1 655 nm). These advantages attract SSMFs-based WDM systems to expand into the U-band

which leads to the extension of WDM-ROF technology into long wavelengths

and in turn leads to the expansion of photogenerated microwave technology. Therefore

this paper studies the photogenerated microwave technology in the U-band.

【Methods】

2

From the mathematical model

the commonly used photogenerated microwave carriers technologies are transparent to the applied optical carrier bands

and can be used to generate microwave carriers at arbitrary bands by selecting photonics devices corresponding to the operating bands. In principle

C-band wavelengths photonics devices (such as polarization controllers

Phase Modulator (PM)

Fiber Phase Shifter (FPS)

etc.) can work in the U-band

and the process technology of these devices is mature. Therefore

in this paper

photonics devices such as C-band wavelengths PM

FPS and optocouplers are used to build a photogenerated microwave carrier system based on U-band optical carriers.

【Results】

2

Finally

tunable microwave carrier with a tuning range of 7.5~12.0 GHz and a spurious rejection ratio of 29.6~35.2 dB is ultimately generated based on this system.

【Conclusion】

2

Through formula principle analysis and experimental verification

this paper extends the working band wavelengths of the photogenerated microwave carrier to the U-band wavelengths.