## 1 Introduction  
A high-power laser driver is an important component of an inertial confinement fusion (ICF) laser system, composed of a front end, preamplifier, main amplifier, target, and other control and diagnostic systems [1; 2]. For high-power laser pulses in the nanosecond regime, spectral broadening in large-scale laser facilities is an essential method to suppress transverse stimulated Brillouin scattering (TSBS) [3]. TSBS is a three-wave coupled nonlinear process, where the incident light energy is converted into transverse scattered light energy, resulting in energy loss; simultaneously, a strong elastic acoustic field is generated in the medium, causing mechanical damage to the optical components. However, increasing the spectral bandwidth can help reduce the threshold of TSBS [4]. In addition, smoothing via spectral dispersion (SSD) is used to smooth the speckle pattern illuminating the target; this also requires the high-energy laser to be spectrally broadened in the time domain [5]. Typically, a low-frequency phase modulation is used to broaden the spectrum of the seed-source laser to reduce the power spectral density, and a high-frequency phase modulator is used to achieve the optical smoothing of the focal spot to meet the physical shooting requirements [6; 7]. Under ideal conditions, when transmitting after phase modulation, the pulse retains its original time-domain characteristics and the spectrum is uniform [8]. Actually, the spectral transfer functions of all the optical components are nonuniform, which is caused by the group velocity dispersion (GVD), polarization dispersion, change in the index of refraction, and nonuniform spectral transmission from clipping by the etalon effects [9]. The spectrum of the phase-modulated broadband light is affected, leading to the generation of FM-AM, when passing through these optical elements with nonuniform spectral transmittance [10]. If no measures are adopted to suppress or compensate for this, FM-AM will influence the power balance of the laser drive and damage the optical components during transmission [11; 12]. In the front end of high-power lasers, the main factors influencing the generation of FM-AM are the polarization mode dispersion (PMD), GVD, and gain-narrowing effect of the regenerative preamplifier [13; 14]. Many researchers have proposed related technical schemes. To eliminate the effect of PMD, [PERSON] proposed using a high-extinction-ratio single polarization [15]. [PERSON] demonstrated a broadband Nd:glass regenerative laser amplifier system with an intracavity birefringent filter to suppress FM-to-AM conversion [16]. [PERSON] used a two-dimensional tunable and temperature-insensitive Lyot filter for compensation [17]. The transmission peak shift was less than that under a normal polarization maintaining fiber (PMF) configuration. Therefore, the GVD is the most important factor influencing the FM-AM conversion for the front end [18]. As we all know, the effect of GVD can be negligible over short fiber distances; however, long fiber distances of several hundred meters are required for transmission in front-end systems, which can produce severe distortions [19]. In addition, [PERSON] proposed that chirped fiber Bragg gratings (CF-BGs) can achieve a better GVD compensation effect, owing to their flexible implementation, low loss, and weak nonlinearity [20]. However, the performance of CFBGs is easily affected by environmental factors. Furthermore, CFBGs introduce a large amount of dispersion and are often used to compensate for long transmission fibers (several kilometers) in communication systems. The high-energy laser facilities, such as the National Ignition Facility (NIF) and Laser Megajoule Facility (LMJ), preferentially use bulk gratings to compensate for GVD [21; 22]. Depending on the synchronization requirements, the injected optical parameters may vary for different fiber lengths; thus, the compensation process needs to be reconstructed, which makes the process time inefficient and time-consuming.