Photonic computing company Lightmatter has raised $400 million in Series D funding, which the company plans to use to prepare its reconfigurable optical interposer Passage for mass deployment in partner data centers. According to the company, its Passage photonic engine technology addresses bottlenecks presented by traditional electronic interconnects by leveraging 3D-stacked photonics chips to move data, increasing AI cluster bandwidth and performance while reducing power consumption. Earlier this year, the MIT spinout named former NVIDIA executive Simona Jankowski as its CFO and added semiconductor and computing specialists Richard Breyer and Robin Washington to its board of directors. Since its last funding announcement in December 2023, Lightmatter has expanded its footprint with an office in Toronto and has continued to grow its workforce. The company has raised $850 million to date and is valued at $4.4 billion.