Summary of the project

In this project, we apply Japan’s strength in blue-violet semiconductor laser technology to the field of fusion, with the aim of establishing a highly efficient laser driver for inertial fusion. Through this approach, we seek to reduce the electrical power required to generate the high-intensity laser pulses necessary for compressing fusion fuel. Furthermore, we challenge the long-standing requirement of approximately 100-fold fusion energy gain for future fusion power plants, with the objective of lowering this requirement to around 20-fold, thereby advancing the practical realization of fusion energy systems.

Specifically, the project will first pursue nanosecond‑pulse operation and high‑output performance of blue–violet semiconductor lasers. While such lasers can, at the device level, achieve continuous‑wave efficiencies exceeding 50%, stable generation of high‑power nanosecond pulses at a repetition rate of around 10 Hz has not yet been achieved.

To overcome this challenge, the project will adopt a Vertical Cavity Surface Emitting Laser (VCSEL) architecture and develop a 10‑J‑class, 1‑nanosecond, 10‑Hz blue–violet semiconductor laser capable of stable operation. Using this 10‑J‑class laser, the project will demonstrate compression of fusion fuel while suppressing laser–plasma interactions, thereby achieving fusion reactions at a repetition rate of 10 shots per second.
Furthermore, to realize a compact inertial‑fusion reactor capable of self‑preservation and autonomous operation even under harsh fusion‑reaction environments involving X‑ray and plasma‑debris heat and particle loads, the project will develop key technologies such as regenerative low‑melting‑point metal mirrors and debris‑shielding structures, and demonstrate their effectiveness. These technologies are expected not only to contribute to inertial‑fusion power systems but also to enable applications in the space domain, including space‑debris removal and space propulsion.

Milestone by 2034

• To stably operate a 10‑J‑class, 1‑ns, 10‑Hz blue–violet semiconductor laser and demonstrate fusion reactions via laser‑driven fuel compression.
• To develop and validate, under fusion‑reaction conditions, key technologies for a self‑preserving, autonomously operated, compact inertial‑fusion reactor—such as regenerative low‑melting‑point metal mirrors and flying‑debris armor—and to develop reactor‑design concepts aimed at future power‑plant deployment.
• To develop application scenarios beyond fusion energy, including space application such as space debris removal.

Milestone by 2029

• To integrate key enabling technologies—vertical stacking, array integration, thermal management, wavefront control, and beam focusing—to establish chip-level performance of blue-violet semiconductor lasers and achieve millijoule-class, 1-ns, 10-Hz operation.
• To demonstrate solid‑surface ablation using semiconductor lasers.
• To complete a conceptual design for a self‑preserving, autonomously operated compact inertial‑fusion reactor, assuming the availability of a high‑efficiency laser driver, and to clarify the technical requirements for commercial reactors and space applications.