A silicon photonics-based high-energy passively Q-switched laser is demonstrated with a compact footprint, achieving pulse energies of over 150 nJ and 250 ns pulse duration in the retina-safe spectral region (1.9 μm) with a slope efficiency of ~40% in a footprint of ~9 mm². This performance is comparable to or exceeds that of fiber lasers. The laser utilizes a rare-earth gain-based large-mode-area waveguide, enabling high energy storage and efficient signal amplification. The design supports a single transverse fundamental mode and allows for tight integration with conventional nonlinear photonics components. The device is CMOS compatible and can be co-integrated with electronics using emerging 3D/2.5D co-integration techniques. The laser operates using a passively Q-switched mechanism with an artificial saturable absorber, which is durable and has a high damage threshold. The laser is capable of generating high-energy pulses with sub-microsecond durations and high beam quality, making it suitable for applications in medicine, space, and other fields where size, weight, and power are critical. The device can be scaled to different wavelength windows and is designed to support larger mode areas for increased energy storage. The laser's performance is validated through experimental measurements, demonstrating its potential for a wide range of applications.A silicon photonics-based high-energy passively Q-switched laser is demonstrated with a compact footprint, achieving pulse energies of over 150 nJ and 250 ns pulse duration in the retina-safe spectral region (1.9 μm) with a slope efficiency of ~40% in a footprint of ~9 mm². This performance is comparable to or exceeds that of fiber lasers. The laser utilizes a rare-earth gain-based large-mode-area waveguide, enabling high energy storage and efficient signal amplification. The design supports a single transverse fundamental mode and allows for tight integration with conventional nonlinear photonics components. The device is CMOS compatible and can be co-integrated with electronics using emerging 3D/2.5D co-integration techniques. The laser operates using a passively Q-switched mechanism with an artificial saturable absorber, which is durable and has a high damage threshold. The laser is capable of generating high-energy pulses with sub-microsecond durations and high beam quality, making it suitable for applications in medicine, space, and other fields where size, weight, and power are critical. The device can be scaled to different wavelength windows and is designed to support larger mode areas for increased energy storage. The laser's performance is validated through experimental measurements, demonstrating its potential for a wide range of applications.