9: Chapter 9 The Birth of the First Prototype

The changes brought about by the "Chasing Light" project were immediate and revolutionary.

The first thing to arrive was an upgrade in access privileges.

Comrade Sun—now Lin Shen knew his name was Sun Qiming, the technical liaison for the early coordination group of the "Chasing Light" project—personally brought a specially security-hardened laptop and opened up a brand-new internal network access channel codenamed "firefly" for him.

Through this channel, Lin Shen could access a top-secret knowledge base named "Star Sea."

When Lin Shen logged into "Star Sea" for the first time, even though he had been mentally prepared, he was still shocked by its vastness and depth.

It not only gathered almost all of the Dragon Kingdom's undisclosed cutting-edge research results, experimental data, failed case analyses, and strategic assessment reports in fields such as photonics, microelectronics, and materials science, but also contained a vast amount of filtered and verified dynamic information from overseas related fields and some non-core raw technical data obtained through special channels.

The magnitude of its information and its level of confidentiality were far beyond anything comparable to any database he had previously been able to access.

More importantly, the "Star Sea" knowledge base possessed powerful intelligent correlation and deduction assistance functions.

When he entered keywords for his research direction, the system could not only retrieve massive amounts of relevant literature but also automatically construct knowledge graphs, marking key nodes on the technical path, known bottlenecks, and potential risks, while also suggesting interdisciplinary connection points that might have been overlooked.

This greatly improved his information processing efficiency and the quality of his deductions.

On the technology tree, the glowing veins around the [Photonic Chip Basic Architecture] node were becoming more solid and detailed at a speed visible to the naked eye.

Many detailed parameters, material phase diagrams, and process windows that originally required him to expend a great deal of energy to deduce or guess could now find partial relevant or adjacent research foundations in the "Star Sea" database, providing him with a solid springboard and basis for verification.

Secondly, there was unobstructed access to resources.

Sun Qiming gave him a list that enumerated all the high-end equipment platforms available for coordination in the early stages of the "Chasing Light" project, distributed across several top-tier research institutes and national laboratories in the capital and its surrounding areas.

From ultra-precision thin-film growth equipment like Atomic Layer Deposition (ALD) and Molecular Beam Epitaxy (MBE), to cutting-edge analytical instruments such as High-Resolution Transmission Electron Microscopy (HRTEM) and Secondary Ion Mass Spectrometry (SIMS), and even some extreme condition experimental devices used for special material synthesis (such as high pressure and strong magnetic fields), as long as he proposed a reasonable experimental plan and passed a brief security and necessity review, he could obtain priority access to machine time.

Lin Shen did not aim too high.

He kept in mind Academician Qin's admonition to "start with small problems" and understood that he must first prove his value with tangible, controllable results to earn deeper trust.

The first phased goal he set was very clear: utilize the resources provided by the "Chasing Light" project to optimize and implement the "selective ion implantation and rapid thermal annealing process" proposed in his application, and prepare a modified interface layer on a silicon wafer with measurable, repeatable, and low optical loss characteristics.

This was not only a key step in verifying his theoretical assumptions but also an indispensable process foundation for building any silicon-based photonic device in the future.

In the small cubicle of the old laboratory building, with the assistance of Sun Qiming and Engineer Li (Engineer Li was temporarily seconded as the confidentiality supervisor and technical support personnel for the "Chasing Light" project in that laboratory), Lin Shen set up a simplified but fully functional pre-experimental platform.

In addition to that old SEM, they also obtained a relatively new ellipsometer (used for measuring thin-film thickness and optical constants), a modified rapid thermal annealing furnace with sufficient precision, and a set of clean workstations for sample pre-cleaning and processing.

The actual ion implantation step required borrowing equipment from the institute's microelectronics process platform.

Under Sun Qiming's coordination, Lin Shen obtained precious machine time.

Carrying his carefully designed mask patterns and strictly cleaned silicon wafers, he walked into that modern process line for the first time, filled with the "humming" sound of the ultra-clean environment and a distinct odor.

The person responsible for operating the ion implanter was an experienced master named Zhao, who possessed superb technical skills, but when he heard that this young man from the old laboratory building, Lin Shen, wanted to conduct "non-standard" optical device-related experiments, and that the combination of doping types and energy doses was very peculiar (based on the results of Lin Shen's deductions and the comprehensive optimization of "Star Sea" data), he couldn't help but frown.

"Young man, your parameters... are a bit unconventional. No one has ever tried this before, so it's hard to say what the success rate will be. If you damage the substrate or if the implantation is uneven..." Master Zhao warned.

"Master Zhao, sorry to trouble you. Theoretical calculations and simulations show that this parameter window is promising, and I would like to give it a try," Lin Shen said sincerely. "Even if it fails, it will still be valuable experimental data."

Considering the "special project" approval slip brought by Sun Qiming, Master Zhao didn't say anything more and, following the parameters provided by Lin Shen, carefully injected beams of rare-earth ions (erbium ions) with specific energy and doses into specific areas on the surface of the silicon wafer.

The silicon wafer looked no different after the injection was completed.

The real challenge lay in the subsequent heat treatment—how to use precisely controlled rapid thermal annealing to activate the injected ions, repair lattice damage, and simultaneously promote the migration and aggregation of ions at the interface to form an ideal structure, rather than simply "driving them away" or forming harmful clusters.

This required precise control over temperature, time, heating rate, and the annealing environment (nitrogen, argon, or forming gas).

Lin Shen based on the large amount of relevant experimental data and thermodynamic simulation results in the "Star Sea" database, combined with his own deductions, designed as many as twenty different annealing process combinations.

Over the next few weeks, Lin Shen almost made the laboratory his home.

During the day, he conducted round after round of annealing experiments in the small cubicle, using the ellipsometer to preliminarily characterize the thin-film changes; at night, he would analyze data, adjust parameters, consult the "Star Sea" database for inspiration, and conduct online discussions with Sun Qiming (who was often able to provide valuable suggestions on engineering practices) via the "firefly" channel.

Engineer Li silently took on more of the daily maintenance and equipment support work, ensuring that Lin Shen's experiments were not disturbed.

He would occasionally stand outside the cubicle, watching the busy figure inside and the flickering indicator lights of the instruments, his eyes complex, not knowing what he was thinking.

Failure was a common occurrence.

After annealing, many samples showed increased loss in optical measurement results, or their parameters were extremely unstable.

Under SEM observation, some samples showed micro-cracks on the surface, while others had obvious non-uniform precipitates at the interface.

Lin Shen was not discouraged.

He recorded every failure in detail and compared and analyzed them with similar cases in the "Star Sea" database.

He gradually discovered that the problem often did not lie in a single parameter, but was the result of the coupling of multiple factors such as the temperature curve, injection damage distribution, interface stress, and atmospheric environment.

He needed a more precise model to guide the process.

Using his newly acquired privileges, he applied for a portion of machine time at the National Supercomputing Center and ran a complex multi-physics coupled simulation program for "ion implantation - thermal annealing - microstructure evolution."

Although computational resources were limited and the simulations had to be simplified, it still revealed several key temperature "windows" and "minefields" that could trigger catastrophic defects.

Based on these new insights, he significantly reduced his experimental matrix, focusing on the three most promising process windows.

After another round of intense experiments, when Lin Shen placed the sample numbered "S7-19" into the ellipsometer, the optical constant curve that jumped onto the screen made him hold his breath.

The spectral lines for the refractive index and extinction coefficient showed a small but very clear "dip" and "platform" near the target wavelength (1550nm communication band).

This meant that in this region, the material's absorption and scattering characteristics for light had changed favorably!

The preliminary estimate of the loss coefficient was nearly an order of magnitude lower than that of the untreated silicon-silicon dioxide interface!

Suppressing his excitement, he immediately placed the sample under the old SEM for observation.

After careful searching and comparison, at the boundary between the modified area and the unmodified area, he saw the long-awaited signs: it seemed that an extremely uniform, dense, and well-bonded amorphous thin layer had formed at the interface with the substrate, without obvious defects or voids.

Although the SEM's resolution was not enough to see the atomic arrangement, the improvement in morphology was obvious.

"Engineer Li! Engineer Sun! Come look at this!" Lin Shen's voice trembled with excitement.

Engineer Li and Sun Qiming (who happened to be on-site today) immediately gathered around.

Looking at the data and images on the screen, both of their expressions turned serious.

"The data looks... interesting," Sun Qiming said, carefully looking at the curve. "How is the repeatability? How many parallel samples were made?"

"For this process combination, three pieces have been made so far; S7-19 is the best one, and the other two also show similar trends, but the degree of optimization is slightly weaker. I am currently analyzing the reasons for the deviation," Lin Shen quickly brought up the data for the other two samples.

"The interface morphology is indeed much more uniform," Engineer Li said, pointing to the SEM image. "It's much better than those lumpy ones from before, which were full of cracks and precipitates. Did you adjust this annealing curve?"

"Yes, I combined it with the simulation results, focused on controlling the heating and cooling rates, and held it at several specific temperatures for a short time," Lin Shen explained.

"Continue to repeat it and expand the sample size. At the same time, measure the loss using a more precise method," Sun Qiming decided decisively. "I will coordinate with partners at the Optoelectronics Institute to help you perform direct measurements of insertion loss and transmission loss using their high-precision optical waveguide test platform. That is much more accurate than indirect estimation via an ellipsometer."

Two days later, a batch of new samples prepared using the optimized process was sent to the Optoelectronics Institute.

Three days later, the test results were sent back.

When Lin Shen saw the test report stamped with "Confidential" in the "firefly" channel, his heart almost jumped out of his chest.

The report showed that at a 1550nm wavelength, the silicon-based modified interface layer prepared using his optimized process had an optical transmission loss that was a full order of magnitude (more than 10 times!) lower than that of the standard thermal silicon oxide-silicon interface, and it showed good repeatability (deviation within 15%) across different batches and different positions on the samples.

Although it was still a huge distance from the theoretical limit and far from the requirements for truly practical ultra-low-loss photonic devices, this was the first time that a significant, directional improvement in interface optical loss had been achieved on silicon, the most mature and mainstream semiconductor substrate, through a repeatable and controllable process!

This was not just experimental data; it was a proof of principle!

It proved that through ingenious ion engineering and heat treatment, it was indeed possible to "tame" the silicon-based interface—the "killer" of photon transmission—and open a new door for silicon-based photonic integration!

The news spread rapidly within a very small circle inside the "Chasing Light" project.

Academician Qin sent a brief congratulatory message immediately: "Initial victory, extraordinary significance. Guard against arrogance and rashness, deepen the mechanism research, and advance toward practical application."

Professor Zhang Mingyuan specifically called, his tone full of emotion and joy: "Xiao Lin, well done! I knew you could do it! The institute is proud of you!"

Sun Qiming even came directly to the old laboratory building, wearing a rare, heartfelt smile: "Comrade Lin Shen, congratulations! The 'Chasing Light' project headquarters has given high praise to your preliminary results. They believe that you have not only verified a key technical path, but more importantly, you have demonstrated a highly valuable research paradigm that closely combines cutting-edge theoretical thinking with solid process practice. The headquarters has decided to officially list 'Silicon-Based Photonic Interface Engineering' as a Class A key support direction for the 'Chasing Light' project and will increase resources for you."

He handed Lin Shen a new document: "This is the preliminary support plan for the next stage. It includes: forming a lean, small research team for you, with members nominated by you and reviewed and allocated by the headquarters; a significant increase in the annual special funding amount; priority guarantee of machine time for you to conduct more in-depth characterization and process experiments at top-tier platforms like the National Center for Nanoscience and Technology; in addition, the headquarters suggests that while you continue in-depth mechanism research, you can start considering the design of the simplest prototype optical waveguide device based on this modified interface for functional verification."

Lin Shen took the document, feeling its weight in his hands.

He knew that he was no longer that marginal person fighting alone in the corner of the old laboratory building.

His work had officially entered the vision of the nation's highest-level strategic technology project and had been endowed with clear expectations and missions.

He walked over to the old SEM, where the clear interface image of the "S7-19" sample was on the screen.

This old piece of equipment had witnessed his struggle from scratch, and it also witnessed this small but solid breakthrough.

The first prototype—perhaps it couldn't yet be called a chip, just an interface layer with improved performance—but it had been born.

It was like a seed that, although small, tenaciously penetrated the thick rock layer, proving that the seemingly impossible path did indeed exist.

The "Dragon Core" path for photonic chips had finally taken its first real, tangible step, landing on the soil of reality from the ethereal deductions and blueprints.

Outside the window, spring was deep; the flowering period of the camphor trees had passed, and the branches and leaves were becoming increasingly lush and deep green, shimmering with vigorous vitality in the sunlight.

Lin Shen knew that even more arduous challenges lay ahead.

Device design, integration, testing... every hurdle was full of thorns.

But his heart was filled with unprecedented confidence and strength.

Because light had already found its first gap through which it could pass more smoothly.