## 5 Experimentally Measuring the PSL of LFM Pulse
### Performance Comparison with the Buffer Made of a Bank of Lasers  
For performance comparison, we replace the Kerr comb with four discrete laser sources. In Figure 10a, we show the modified setup of the optical memory buffer, where we use four lasers with <10 kHz linewidth (Teraxion TNL). The lasers are set to the wavelengths of 1540.16 nm, 1544.92 nm, 1549.72 nm, and 1554.54 nm as shown in Figure 10b. Every laser emits \(\sim\)10 dBm of optical power with more than 35 dB of optical OSNR. We repeat the same systematic analysis of the prior subsection for penalty analysis.  
In Figure 11a, we measure the PSL of the LFM pulses when we send the signal through the optical buffer while bypassing the FBGs. The measured PSL values are 36.78-37.43 dB due to the non-flat frequency response of the optical system of the modulator and detector. We design a digital filter \(H(f)\) for each channel and apply the filter. The PSL values become similar to the baseline at 42.68 dB as shown in Figure 11b. Then, we insert the FBGs into the optical buffer system and measure the PSL as in Figure 11c. The measured PSL values range between 41.11 and 41.32 dB for the delayed pulses, indicating a PSL penalty of only 1.36-1.57 dB.  
Figure 9: **(a)** The PSL for three versions of the LFM pulse after compression when the FBGs are bypassed in the optical delay buffer. **(b)** The PSL for three delayed versions of the LFM pulse after compression and after using the equalization filter \(H(f)\). **(c)** The PSL for three delayed versions of the LFM pulse after compression when inserting the FBGs for the delay and using the equalization filter \(H(f)\).  
Figure 10: (**a**) The modified setup for measuring the PSL of an LFM pulse that is delayed using the optical buffer. (**b**) The spectrum of the FBG delay channels and the wavelengths of the laser carriers.  
For further analysis, we investigate increasing the LFM pulse bandwidth to 10 GHz at a center frequency of 5 GHz (10 times greater bandwidth than the precedent experiment). This study could validate the benefit of concatenating the LC-FBG and CS-FBG. Here, we repeat the systematic analysis approach, where in Figure 12a,b, we show the captured 10 GHz bandwidth LFM pulse experimentally in the time and frequency domains in the back-to-back RF configuration. In Figure 12c, we show the compressed pulse in the back-to-back configuration after applying a matched filter and windowing, where the compressed pulse shows a PSL of 42.68 dB. Figure 12c-e show the PSL when we send the signal through the optical memory buffer while bypassing the FBGs, the PSL when we insert the FBGs into the optical buffer system, and the PSL when we design and apply the digital filter \(H(f)\). The results in Figure 12e show that the system can potentially be used to delay broadband signals with a penalty of 3.95-6.7 dB.  
Figure 11: The results when we replace the Kerr comb carriers with a bank of lasers. (**a**) The PSL for the four versions of the LFM pulse after compression when the FBGs are bypassed in the optical delay buffer. (**b**) The PSL for the four versions of the LFM pulse after compression and after using the equalization filter \(H(f)\). (**c**) The PSL for the four delayed versions of the LFM pulse after compression when inserting the FBGs for the delay and using the equalization filter \(H(f)\).