18 December 2020
POET unveils first flip-chip DML lasers
POET Technologies Inc of Toronto, Ontario, Canada — designer and developer of the POET Optical Interposer and photonic integrated circuits (PICs) for the data-center and telecom markets — has completed and tested its high-speed directly modulated laser (DML) designs using a distributed feedback (DFB) structure and flip-chipped these lasers onto its Optical Interposer platform, which also incorporates several other industry-first accomplishments, it is claimed.
The flip-chip assembly technique enables a true single-chip, fully integrated Optical Engine to be produced at wafer scale, resulting in what is reckoned to be the lowest-cost, smallest-size 100G CWDM4 Optical Engine (with a form factor of 9mm x 6mm), while including banks of four lasers, four monitor photodiodes, four high-speed photodiodes, a multiplexer, demultiplexer, taps for power monitoring and features supporting a self-aligned fiber attach unit.
“Without being able to flip-chip the lasers, we would be unable to assemble Optical Engines at wafer scale, which is the single most important driver of cost,” says chairman & CEO Suresh Venkatesan. “Wafer-scale processing enables the production of high unit volumes at low incremental costs, ultimately allowing us to reduce the cost of building photonics devices by 25-40% compared to conventional approaches,” he adds. “Following our successful demonstration of this flip-chip assembly process, POET can now readily incorporate these lasers and other active devices into derivative optical engine configurations, supporting data communications applications such as 200G CWDM4, 100G CWDM6 and 100G LR4, telecom applications such as 5G, as well as other applications that could benefit from the small size and low cost of our platform technology.”
Four DML lasers are commonly used in 100G transceiver applications (a key initial target market for POET’s Optical Interposer), enabling high-speed optical communication in the 2-10km range. Operating at speeds of 25Gb/s, POET’s family of four DML lasers of different wavelengths comprise the first known commercial 25G DFB-type DML lasers to utilize a flip-chip process to passively align and bond to electronic and optical circuitry on the interposer platform, while maintaining optimal performance. Given the estimated total available market (TAM) for 100G transceivers of about $2.5bn, POET believes that its recently formed joint venture SuperPhotonics Xiamen can achieve annual revenue of over $100m within this single market segment in the 2024-25 time frame.
Flip-chip assembly of electronic devices on circuit boards, MEMS (micro-electro-mechanical systems) and other devices is a manufacturing process for achieving electrical interconnection (2D, 2.5D and 3D) in semiconductor architectures. To achieve the benefits of the planar architecture of POET’s Optical Interposer that facilitates wafer-scale processing, flip-chipping of lasers was an important development milestone, requiring POET to demonstrate that it could simultaneously optimize the radio-frequency performance of the flip-chipped DML laser on interposer while preserving a low RIN (relative intensity noise) measurement both before and after assembly.