Fig. 1. Energy level diagram of cesium atom

Fig. 2. Schematic of Rydberg atom EIT setup (λ/2 represents half-wave plate, PBS represents polarizing beam splitter, SAS represents staturated absorption spectrum, lock-in ＋PID represents lock-in and PID module; current represents the drive current port of laser; PZT represents piezoceramics; YDFA represents ytterbium-doped fiber amplifier, PPLN represents periodically poled lithium niobate, wavemeter represents Highfiness WS-7 wavelength meter, PD represents photodetector)

Fig. 3. Schematic of cat-eye configure laser setup (diode represents laser emitter; col lens represents collimating lens; filter represents a narrow bandwidth filter, the emission beam wavelength can be changed via rotating the filter angle θ；OC represents the output plate)

Fig. 4. Saturated absorption spectrum (SAS) signal of 852 nm laser and error signal after demodulating SAS signal

Fig. 5. Matched temperature curve of 509 nm doubled frequency system (the fundamental wavelength is 1018.9 nm, the optimal temperature is 51.9 ℃，and the full width at half maxima is 0.9 ℃)

Fig. 6. Relationship between output second-harmonic laser and injected fundmental wave powers

Fig. 7. EIT signal in different coupling beam powers (vertical axes represent transmitted intensity of probe beam, horizontal axes represent frequency detuning of coupling beam)