In recent years, the surge in Co-packaged optics (CPO) exploration has been driven by the escalating demand for faster data processing, notably at speeds of 400 Gb/s, 800 Gb/s, and 1.6 Tb/s in Ethernet networks. This particular technology stands out by seamlessly integrating optical components with compute engines, enabling more efficient designs. However, the absence of established techniques to efficiently power densely packed chip-level optical links remains a significant challenge in this technology. To overcome this, it has become imperative to redirect substantial focus toward improving the capabilities of lasers integrated into CPO systems.
The exceptional characteristics and compatibility of DFB lasers has made it widely utilized as optical source in CPO. Their hybrid integration with silicon chips, combined with attributes such as precise wavelength control, narrow linewidth, single-mode operation, reliability, and optical fiber compatibility, makes them a practical and efficient solution for enabling robust and high-performance optical communication systems in data center environments. By optimizing DFB lasers to deliver higher output power, it becomes feasible to mitigate the power constraints that impede the scaling and performance of CPO systems.
The main objective of this thesis is to conduct a comprehensive analysis aimed at enhancing the performance of Distributed-Feedback (DFB) lasers for different wavelength channels, specifically engineered for use as light sources in co-packaged optics. These laser channels are individually designed with distinct grating pitches. Our approach involves employing a cascading technique that integrates multiple partially corrugated DFB lasers to showcase superior performance compared to the conventional PCG-DFB standard. Throughout this study, we have extensively investigated the partially corrugated grating distributed feedback (PCG-DFB) structure, implementing up to 10 segmentations, where each segmentation comprises a Fabry-Perot and grating section.
The device characterization in this study encompassed various analyses including L-I curves, Relative Intensity Noise (RIN), optical spectrum, and linewidth evaluation of the PCG-DFB structure. L-I results unveiled notable findings: for grating length (Lg) of 400 μm, the device with the highest segmentation (S = 5) demonstrated a peak power (Ppeak) of 224.83 mW, showcasing a 12.07% increase compared to S = 1. Similarly, Lg = 500 μm, S = 10 exhibited a significant enhancement of 13.74% in Ppeak, while Lg = 600, S = 5 displayed an 8.2% increase. Channel D achieved the highest output power across all wavelength channels achieving 231.1 mW output with slope efficiency >0.4395 mW/mA reaching the minimum demanded output power of light sources for co-packaged optics. The RIN characteristics displayed reduced relative intensity noise with increased segmentation, with the lowest measured RIN of -169.29 dB/Hz for Lg 400 µm, S=5, -170 dB/Hz for Lg 500 µm, S=10, and -168.61 dB/Hz for Lg 600 µm, S=5. Additionally, the optical spectrum showcased a consistently high side mode suppression ratio (>50 dB) for all PCG-DFB devices. Lastly, experimental linewidth results showed a significant improvement with increased segmentation. Notably, Lg = 500 µm, S=5 exhibited the narrowest linewidth of 16.95 kHz.
The experimental results confirm a successful performance enhancement by increasing the partitions of the PCG-DFB devices. The efficacy of this novel technique has been validated, effectively meeting the stringent requirements for a laser source within co-packaged optics, showcasing its capability to address the industry's demands for efficient and high-performing optical systems.

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