Fig. 1. Block diagram of the millimeter wave noise source generated by ASE light beating. (ASE: amplified spontaneous emission; OC: optical coupler; EDFA: erbium doped fiber amplifier; PD: photodetector)

Fig. 2. The excess noise ratio versus the ASE noise power P₀ at 100 GHz

Fig. 3. The relationship between the excess noise ratio and the PD responsivity at 100 GHz(σ=0.1 nm，P₀=10 dBm) 100 GHz处的ENR与PD响应度 的关系曲线（σ=0.1 nm，P₀=10 dBm）

Fig. 4. The variation of the excess noise ratio and the 3 dB bandwidth of the noise source with the linewidth of two Gaussian optical noises.（@100 GHz, = 0.35 A/W, P₀=15 dBm） 噪声源的ENR和3 dB带宽分别与两个高斯光噪声线宽σ的关系（@100 GHz， = 0.35 A/W，P₀=15 dBm）

Fig. 5. (a) Two channel spectra of the ASE noise source filtered and shaped by two optical filters; (b) the spectra of the filtered two beams after coupling

Fig. 6. Power spectra of the broadband millimeter-wave noise (RBW=1 MHz) at different center frequencies. (a) 25 GHz; (b) 35 GHz. Red: experiment; blue: simulation

Fig. 7. Experimental and simulation results of the excess noise ratio of the millimeter-wave noise source