Scaling Up Production of Integrated Tunable Lasers

Introduction

The global demand for data and telecommunication services is soaring, driven in large part by initiatives like "Broadband China" and the rapid expansion of 5G networks in Asia. To meet this growing need, the industry is turning to compact, power-efficient, and scalable laser solutions that integrate all necessary functions onto a single chip.

One key technology at the forefront of this trend is the integrated tunable laser. Tunable lasers, combined with dense wavelength division multiplexing (DWDM), allow telecom and datacom networks to expand their capacity without the need for additional fiber infrastructure. Furthermore, the miniaturization of coherent technology into pluggable transceiver modules has enabled the widespread implementation of IP over DWDM solutions.

As the demand for coherent transceivers continues to rise, companies are consolidating through acquisitions and mergers to develop transceiver components internally and secure their supply. While this consolidation is expected to decrease sales of individual modulator and receiver components, the demand for tunable lasers is forecast to grow significantly. LightCounting market data projects the tunable laser market for transceivers to reach $400 million in 2026 (Figure 1).

Figure 1: Global Market sales for high-performance modulators and receivers as well as tunable lasers. (Historical Data and Forecast).

The Challenge of Scaling Integrated Tunable Lasers

To meet the growing demand for tunable lasers, the industry must address the challenge of making highly integrated, compact, and power-efficient laser solutions at scale. Smaller laser designs inherently operate at lower voltages and currents, offering improved heat dissipation and minimizing coupling losses. Photonic integration plays a crucial role in achieving these reductions, consolidating multiple functions onto a single chip to maximize efficiency.

The transition to 100G coherent technology in access networks requires compact and power-efficient coherent pluggables in the QSFP28 form factor. This, in turn, necessitates the development of compact and power-efficient tunable lasers that can fit within this form factor.

EFFECT Photonics has addressed this challenge by developing a novel pico-ITLA (pITLA) module, which it claims is the world's smallest integrated tunable laser assembly (ITLA) for coherent applications. The pITLA integrates all laser functions, including the wavelength locker, onto a single chip, occupying just 20% of the volume of a standard nano-ITLA module (Figure 2).

Figure 2: Volume reduction of ITLA form factors for coherent optics (2011-2023). A match of roughly 4cm in length is included for scale.

The key to EFFECT Photonics' approach is the monolithic integration of all tunable laser functions on a single chip. This setup is ideal for reducing power consumption and scaling into high production volumes.

The Economics of Scaling Photonics

As innovative as these new, small lasers may be, their impact will be limited if they cannot be manufactured at a high enough volume to satisfy the demands of mobile and cloud providers and drive down the cost per device. This economy-of-scale principle is the same one that has driven the success of the electronics industry, and it must be applied to the photonics industry as well.

The more optical components that can be integrated into a single chip, the more the price of each component can decrease. Similarly, the more optical System-on-Chip (SoC) devices that can be produced on a single wafer, the more the price of each SoC can decrease.

Researchers at the Technical University of Eindhoven and the JePPIX consortium have modeled the impact of this economy-of-scale principle on photonic integrated chips (PICs). Their analysis shows that if production volumes can increase from a few thousand chips per year to a few million, the price per optical chip can decrease from thousands of Euros to mere tens of Euros (Figure 3).

Figure 3: Modelling of photonic integrated chip (PIC) cost as a function of aggregate number of PICs produced per year. Exponential increases in production lead to an exponential decrease in cost.

Learning from Electronics Manufacturing

To achieve these economies of scale in photonics manufacturing, the industry can learn from the well-established and standardized techniques used in electronics packaging, assembly, and testing.

One key electronic technique that is essential to transfer into photonics is ball-grid array (BGA) packaging. BGA-style packaging has grown popular among electronics manufacturers over the last few decades. It places the chip connections under the chip package, allowing more efficient use of space in circuit boards, a smaller package size, and better soldering (Figure 4).

Figure 4: Top, bottom, and side views of a ball-grid array (BGA) style package.

Another critical technique to move into photonics is flip-chip bonding. This process involves depositing solder bumps on the chip in the final fabrication step, then flipping the chip over and aligning it with a circuit board for easier soldering (Figure 5).

Figure 5: Simplified steps of the flip chip bonding process.

Leveraging these well-established electronic manufacturing techniques can help the photonics industry overcome the challenges of scaling production and driving down costs. By modifying existing production flows, companies can avoid the high costs associated with building entirely new specialized production lines.

Strategies for Scaling Integrated Tunable Lasers

To effectively scale the production of integrated tunable lasers and realize the benefits of economies of scale, companies can employ the following strategies:

1. Photonic Integration: Integrate as many laser functions as possible onto a single chip, as demonstrated by EFFECT Photonics with their pITLA module. This reduces power consumption, package size, and manufacturing complexity.

2. Leverage Electronic Manufacturing Techniques**: Adopt proven electronic packaging, assembly, and testing methods, such as BGA packaging and flip-chip bonding, to streamline the production process and reduce costs.

3. *Increase Production Volumes**: Invest in the capacity to produce millions of optical chips per year, rather than just thousands, to drive down the per-unit cost dramatically, as shown in the Eindhoven University model.

4. Collaborate and Consolidate**: Engage in strategic acquisitions, mergers, and partnerships to combine resources, expertise, and manufacturing capabilities, enabling the industry to scale more effectively.

5. Optimize Design for Manufacturing**: Work closely with foundries and packaging providers to optimize the design of integrated tunable lasers for high-volume, low-cost manufacturing from the outset.

By implementing these strategies, the photonics industry can harness the power of economies of scale to make compact, power-efficient, and affordable integrated tunable lasers available to the growing global market for data and telecommunications services.

Conclusion

The surging demand for data and telecommunications, particularly in Asia, is driving the need for more compact, power-efficient, and scalable laser solutions. Integrated tunable lasers are at the forefront of this trend, offering the flexibility and performance required to meet the industry's evolving needs.

To effectively scale the production of these integrated tunable lasers, the photonics industry must apply the same principles of economies of scale that have proven successful in the electronics industry. This includes leveraging photonic integration, adopting established electronic manufacturing techniques, and increasing production volumes to drive down costs.

By embracing these strategies, companies can overcome the challenges of scaling integrated tunable laser production and make these advanced optical components widely available to mobile and cloud providers, enabling the continued growth and expansion of global data and telecommunication networks.

Reference

[2] EFFECT Photonics, "Making Smaller Lasers at a Big Scale," EFFECT Photonics Insights, April 10, 2024.