## 2 Related Work  
Photonic radar technology has emerged as a promising solution for high-resolution target detection in various environmental conditions. Previous research has demonstrated the potential of photonic radar systems to achieve superior performance compared to traditional microwave radars. In 2020 [8], researchers showcased a photonic radar system capable of detecting drone movement within a range of 2.7 km. Moreover, this technology has the capability to capture real-time images of drones from a considerable distance, specifically up to 1.1 km away. In 2021 [11], researchers introduced the innovative concept of microwave photonic radar, a technology designed for accurately detecting the distance and velocity of various targets. This proposed technology achieved a maximum relative error of 2.6% for distance measurements and 0.21% for velocity measurements [11]. Another work in 2021 [12] proposed a photonic-based approach to generate multiple linearly frequency-modulated (LFM) signals using a dual-parallel Mach-Zehnder modulator. The approach generates two single-tone optical sidebands and the 1 st and 2 nd order optical sidebands of a dual-band LFM signal. In an experiment, eight LFM signals up to 27 GHz in different frequency bands were simultaneously generated, and their performance was verified. Likewise in 2021 [13], researchers proposed a photonics system that simultaneously measures the angle of arrival (AOA) and frequency, suppressing undesired frequency mixing and using the Van Cittert-Zernike theorem to estimate AOA from different RF sources. A proof-of-concept experiment successfully measured multiple targets with different frequencies and distinguished incoherent microwave sources. Atmospheric in-homogeneities such as fog, rain, snow, and dust can significantly impact the performance of photonic radars [14]. Equalization is a critical signal processing technique used in photonic radars and optical communication systems to improve system performance by compensating for these in-homogeneities [15]. This process involves adjusting the amplitude and phase of the received signal to mitigate the effects of linear and non-linear distortions caused by various factors. Linear equalization uses a linear filter to correct for linear distortions, while non-linear equalization uses a non-linear filter to correct for non-linear distortions. IIR filters, which have a feedback structure, are commonly used for equalization and noise-filtering tasks in optical communication systems [16; 17]. These filters can compensate for various distortions and filter out noise components while preserving the signal of interest, improving the overall system performance. The IIR filter offers several key benefits over Finite Impulse Response (FIR) filters, including its superior efficiency, the straightforwardness of its optical architecture, and its ability to tolerate loss. To the best of the author's knowledge, the use of IIR filters in photonic radars has not been reported. In 2021 [18], researchers demonstrated the development of an optoelectronic oscillator (OEO) that achieved high side-mode suppression. This was accomplished by integrating a phase modulator-based single pass band tunable microwave photonic filter with an IIR (Infinite Impulse Response) MWP (Microwave Photonic) filter. The OEO was capable of providing RF (Radio Frequency) oscillation within a tunable frequency range of 6.5 GHz to 17.8 GHz, along with a phase noise lower than \(-103\) dB\({}^{\circ}\)Hz. Notably, the IIR filter contributed to a reduction in phase noise by 20 dB and enhanced side-mode suppression by 10 dB. This OEO was utilized to generate a Terahertz (THz)signal at 242.6 GHz, successfully transmitting a signal of 24 Gbps over a 40 km fiber length and a 30 cm wireless path, maintaining a low bit error rate. This advancement signifies a significant step in the field of high-frequency signal processing and transmission. In 2023 [19], a study proposed a novel Adapt IIR Filter for removing noise interference in fetal ECG signals.