The photonics industry is entering one of the most transformative phases in its history. Once seen as an emerging technology, photonic integrated circuits (PICs) have become fundamental to some of the world’s fastest-growing markets. Artificial intelligence, cloud computing, data center interconnects, LiDAR, quantum computing, and next-generation telecom networks all rely heavily on compact, power-efficient optical circuits. Analysts project the PIC market to surge from approximately $14-17 billion in 2024-2025 to $65-98 billion by the early 2030s, a staggering ~20% CAGR that reflects the explosive momentum behind advanced photonics.

Yet beneath this success story lies a serious and persistent challenge: how to improve the imperfect manufacturing yield.

As PICs integrate more complex optical architectures, nanometer-scale variations in waveguide geometry can introduce significant phase errors. These errors degrade device performance and push a substantial portion of dies outside acceptable specifications, ultimately limiting scalability and profitability.

This systemic challenge is so fundamental that it threatens to bottleneck the industry just as global demand reaches unprecedented levels.

The Yield Problem: Implications of Nanometric Variations on Profitability

Photonic wafers are fabricated using highly controlled lithography and etching techniques; however, even the most advanced processes introduce minimal dimensional deviations, often only a few nanometers, that affect the effective refractive index of waveguides. While such variations may be manageable in basic circuits, they present significant challenges for complex applications involving tens, hundreds and even thousands of arrays of Mach-Zehnder interferometers (MZIs), filters, switches, or resonators, where these minor discrepancies can result in substantial phase misalignments.

This issue manifests in two principal outcomes:

  • Firstly, a notable number of dies do not meet wafer-level testing criteria, as their spectral response falls outside required tolerances (known bad dies). 
  • Secondly, even chips that pass (known good dies) require active tuning to adjust the phase. This increases system complexity, power consumption, and creates long-term reliability concerns.

Currently, photonic integrated circuits (PICs) frequently utilize thermal phase shifters (TPS) to address manufacturing imperfections. Each heater individually changes the refractive index by applying localized heat to the waveguide. Reliance on TPS introduces several drawbacks:

  •    Constant electrical power consumption, often tens of milliwatts per heater
  •   Increased chip size and routing demands
  •    Elevated thermal loads necessitating robust cooling solutions
  •    Decreased device reliability due to continuous heating and repeated thermal cycling

As the complexity of PICs advances to support artificial intelligence and quantum photonics applications, architectures dependent on TPS become both economically and electrically unsustainable.

The photonics sector now faces critical challenges driven by manufacturing yield constraints and the need for improved power efficiency, rather than by limitations in design.

Laser Trimming: A Permanent Solution to Manufacturing Errors

Femtum’s laser trimming technology offers a breakthrough approach to correcting fabrication errors directly at the wafer or die level. Unlike previous trimming techniques that targeted the silicon waveguide itself, which showed high and unacceptable optical losses because of amorphisation, Femtum’s process operates through a novel indirect mechanism.

Instead of modifying silicon, the laser is tightly focused into the glass cladding surrounding the waveguide. The laser pulse induces a small, highly localized modification in the glass matrix to create a stable stress field. Through the elasto-optic effect, that stress alters the waveguide’s effective refractive index, enabling highly controlled phase shifts.

Key characteristics of the process include:

  • High linearity per pulse, enabling predictable incremental tuning
  • Permanent correction, eliminating the need for continuous electrical power
  • Ultra-low insertion loss (<0.1 dB added loss)
  • Sub-micron spatial localization for precise phase alignment
  • Fast processing, with each correction taking milliseconds
  • Automation-ready integration with standard wafer-level testers

The result is a reliable, scalable method for restoring phase accuracy across an entire wafer.

Turning Failed Dies into Revenue

One of the most transformative impacts of laser trimming is its ability to recover dies that would otherwise be discarded.

Figure 1: Impact of FEMTUM’s laser trimming on Photonics Integrated circuit spectral response.

Before trimming, the spectral responses across dies show wide variability, with many failing to meet specifications. After trimming, responses become tightly grouped around the target, significantly improving yield.

This transforms wafer economics:

  • Less waste
  • More sellable chips
  • Higher ROI per wafer
  • Greater process resilience against variation

Laser trimming can be deployed directly into the manufacturing line, after existing wafer testing stations. Dies that fail are automatically redirected to the trimming system, corrected, and returned to the validated flow. It’s a high-throughput, low-disruption process that fits seamlessly into current manufacturing lines.

Overcoming the Yield Barrier

The fast-growing PIC market needs efficient manufacturing. Femtum’s laser trimming technology tackles yield issues and enables improved performance, scalability, and design flexibility.

In a world where nanometers define success or failure, laser trimming isn’t just a manufacturing step. It’s a strategic enabler for the entire future of integrated photonics.