Development of On-Board Optics Technology for TF-LN Device

News

March 25, 2025
Fujitsu Optical Components

Development of On-Board Optics Technology 

for TF-LN Device

~Towards the High-Performance, Compacto, and Low-Cost Optical Components~

【Background and Overview】

With the rapid growth of internet traffic due to the widespread adoption of generative AI, streaming services, and more, the demand for higher treansmission capacity in optical networks continues to grow. Optical transceivers used in these optical networks are required to be not only high-capacity but also compact, low-cost, and low-power. FOC has been developing high-performance thin-film lithium niobate (TF-LN) modulator device that enable faster and more efficient operation compared to conventional bulk LN modulator. This time, we have developed an on-board optics technology that directly mounts these TF-LN device onto PCB boards used in optical transceivers and other devices, and established as a mass-production technology. By applying this technology, it is possible to realize compact and low-cost optical transceivers and optical devices that meet the performance requirements of the 800Gbps generation.

【Technology】

FOC has pioneered the development of a wideband and low-loss thin-film lithium niobate (thin-film LiNbO₃: TF-LN) modulator that supports a modulation rate of 128 Gbaud. Conventionally, such optical devices were mounted in hermetically sealed packages using materials such as ceramics or stainless steel before being integrated into optical transceivers (Fig. 1 Right). This type of implementation has been a limitation in achieving compact, low-cost, and high-speed performance for optical transceivers.

In contrast, FOC has now developed an on-board optics technology that directly mounts these high-performance TF-LN optical modulator onto PCB boards commonly used inside optical transceivers (Fig. 1 Left). As shown in the figure, not only the TF-LN modulator device, but also Si-photonics device used on the receiver does not require a thermoelectric cooler (TEC), making it possible to apply this on-board optics technology without hermetic sealing.

The technology developed this time provides the following advantages:

1. Cost Reduction: By using this developed technology, it is possible to directly mount the device on a low-cost PCB board without using hermetically sealed packages, which are a factor in increasing costs.

2. Low Power Consumption: While compound semiconductor optical devices require a TEC with high power consumption, this technology eliminates the need for a TEC, enabling a reduction in power consumption.

3. Increased Transmission Capacity: Furthermore, by eliminating the optical device package and the TEC with large size, high-speed electrical signal wiring can be achieved between the optical devices and electronic circuits such as drivers, transimpedance amplifiers and DSPs for signal processing, with close proximity placement on PCB or package boards suitable for high-speed transmission, without the need for BGA (Ball Grid Array) terminals or flexible cables. This technology enables to reduce the electrical signal loss between circuit elements by approximately half (5dB at 130GHz) compared to conventional packaging. It is also possible to expand this technology to the next 1.6Tbps generation beyond 800Gbps.

Fujitsu Optical Components Limited

Sales & Marketing Div.
E-mail： foc-contact-pr@dl.jp.fujitsu.com

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