Butterfly Packages in Depth — Why Do High-End Optical Modules All Choose Them?

I. The Structural Code of the Butterfly Package: Why the “Wings”?

If the TO package is economy class, the butterfly package is business class — more room, more features, more pins. It takes its name from the pins on both sides, which resemble a butterfly’s wings, and has three structural hallmarks:

Pins on both sides— 14 pins or even more are led out from both sides of the body, simultaneously carrying multiple signals such as laser drive, TEC temperature control, and monitor-photodiode feedback.

Large planar mounting platform— the package cavity can hold a TEC, thermistor, monitor detector, and other components, like a miniature “motherboard.”

Pigtail exit— a fiber-coupling port at one end of the body couples the laser directly into the fiber output, with the optical path fully sealed.

II. Fiber Coupling: Where Hermeticity Meets the Optical Path

The most demanding step in butterfly packaging is fiber coupling: the light emitted by the laser chip must be precisely aligned and coupled into a single-mode fiber.

Once coupling is complete, the fiber is fixed in position and the body receives its final hermetic seal. Every link in the chain — die attach, wire bonding, fiber coupling, seam welding — sets the performance ceiling of the optical module.

Xuri’s butterfly package product line (BTF-30*12.7-S, 14PIN side-window, 8PIN packages, etc.) supports TEC integration and customized pin layouts, providing package bases for high-speed optical-module and pump-laser customers.

[Next Episode] Next time: the two routes of ceramic packaging — HTCC or LTCC, how to choose?

[Glossary]

1. Pigtail: an optical fiber fixed to the package body and routed out from inside the package

2. Fiber Coupling: the precision process of aligning and coupling laser output light into an optical fiber

3. Monitor Photodiode: a detector inside the package that monitors laser output power