Fig. 1. Rydberg atom AM microwave demodulation system and four energy levels. (a) Block of Rydberg atom demodulation system; (b) ¹³³Cs ladder-type four energy levels

Fig. 2. Relationship curves about probe laser transmissivity, microwave electric field intensity and coupling Rabi frequency

Fig. 3. Relationship between 1 cm-length-atom-cell gain coefficient and coupling laser, microwave electric field intensity. (a) Three-dimensional diagram; (b) left view; (c) right view; (d) vertical view

Fig. 4. Relationship among ¹³³Cs 1 cm-length-atom-cell gain coefficient extreme, C-band microwave frequency and energy level parameters under frequency-zero-detune. (a) Atom cell gain coefficient extreme and microwave frequency; (b) microwave frequency and electric dipole moment of 3, 4energy levels; (c) microwave frequency and 3 spontaneous decay rate; (d) microwave frequency and 4 spontaneous decay rate