###### Abstract
This system is suitable for the modulation formats of BPSK and QPSK. [PERSON] et al. developed a phase-locking-free all-optical matching system based on squarers and negators for 100-Gbaud QPSK optical signals [17]. These all-optical matching systems have contributed significantly to the implementation of photonic firewalls. However, most all-optical matching systems are mainly verified through simulations, which create an ideal environment without noise. In actual applications, noise is inevitable and can lead to incorrect matching results. In this study, we investigated the effects of noise on the QPSK-oriented all-optical matching system reported in [16]. In addition, we studied how to reduce the influence of noise on the all-optical matching system to improve its matching results in real applications. Several theoretical and experimental studies have been conducted to improve the extinction ratio (ER) and contrast ratio (CR) of the output signal of all-optical matching systems and achieve noise compression through all-optical processing. Because the final matching results of QPSK-oriented matching systems are represented by the power of the optical signal, it is important to reduce the effect of noise on the final power. Studies on the anti-noise of the optical signal's power have mostly employed the high nonlinearity of all-optical devices to achieve noise suppression. The most common method is the use of a reamplification and reshaping (2R) regenerator based on the self-phase modulation (SPM) effect, including optical amplifiers, high-nonlinearity devices, and filters. This technique broadens the spectrum through the SPM effect and uses a filter with a certain deviation away from the center frequency to save the optical signal and filter out noise. [PERSON] et al. proposed an all-optical regeneration circuit based on the SPM effect [18]. The circuit regenerates deteriorated 10 Gbps return-to-zero (RZ) code modulation signals. [PERSON] et al. employed the XPM effect in HNLF to achieve the all-optical regeneration of 40 Gbps OOK signals [19]. [PERSON] et al. optimized the parameters of an attenuator-based nonlinear-optical loop mirror (Att-NOLM) to perform the phase-preserving amplitude regeneration of MPSK [20]. [PERSON] et al. reported 2R regeneration based on the cross-gain compression (XGC) effect in SOA at a speed of 100 Gbps with the RZ-OOK format [21]. [PERSON] et al. used a wavelength-shift-free, single-SOA regenerator to achieve the noise suppression of the 28 Gbps signal [22]in 2020. Recent studies have focused on achieving anti-noise functions using the FWM effect. Based on the FWM effect, [PERSON] et al. used higher-order idler light as the regenerated signal to achieve all-optical regeneration [23]. [PERSON] et al. reported multiwavelength 2R regeneration for RZ-modulated OOK signals based on the FWM effect using idler frequency light as the regenerated signal [24]. [PERSON] et al. proposed and simulated an all-optical regeneration and format conversion scheme about the input 4 APSK signal based on the FWM and SPM effects in HNLF in 2023 [25]. Noise suppression based on the FWM effect is achieved by sending the signal and pump lights to highly nonlinear optical devices, generating an idler light with the same characteristics as the signal light at a new frequency and using the saturation effect to make a limiter to suppress noise. Compared with the SPM and XPM effects, the FWM effect exhibits the best shaping effect. However, when using the FWM effect of HNLF to suppress noise, the input power required for signal regeneration is limited. Noise-suppression structures, therefore, expand the range of the input power. [PERSON] et al. proposed a second-order noise-suppression structure based on HNLF for OOK-oriented all-optical matching systems [26]. In this study, we investigate an anti-noise, phase-modulated all-optical matching system and develop a second-order noise-suppression structure to optimize the QPSK-oriented all-optical matching system.