This article presents a silicon photonics-based passively Q-switched laser that generates high-energy optical pulses with a compact footprint. The laser operates in the retina-safe spectral region (1.9 μm) and achieves pulse energies of over 150 nJ and durations of 250 ns, with a slope efficiency of approximately 40% in a footprint of about 9 mm². This performance is comparable to or exceeds that of many benchtop Q-switched fiber lasers, making it suitable for applications in medicine and space. The laser is based on a rare-earth gain-based large-mode-area (LMA) waveguide, which supports a mode area of several tens of square micrometers while allowing for a long cavity within a compact design. The device is CMOS compatible and can be co-integrated with electronics using emerging 3D/2D co-integration techniques. The laser's operation is enabled by a nonlinear Michelson interferometer-based saturable absorber (NLI-SA), which acts as an intensity-dependent reflector, increasing reflectivity with signal intensity. The NLI-SA's reflectivity curve can be tuned to switch the laser between pulsed and continuous wave (CW) modes, offering flexibility for various applications such as laser surgery and LiDAR systems. The study demonstrates the potential of silicon photonics for high-energy, compact, and efficient laser applications.This article presents a silicon photonics-based passively Q-switched laser that generates high-energy optical pulses with a compact footprint. The laser operates in the retina-safe spectral region (1.9 μm) and achieves pulse energies of over 150 nJ and durations of 250 ns, with a slope efficiency of approximately 40% in a footprint of about 9 mm². This performance is comparable to or exceeds that of many benchtop Q-switched fiber lasers, making it suitable for applications in medicine and space. The laser is based on a rare-earth gain-based large-mode-area (LMA) waveguide, which supports a mode area of several tens of square micrometers while allowing for a long cavity within a compact design. The device is CMOS compatible and can be co-integrated with electronics using emerging 3D/2D co-integration techniques. The laser's operation is enabled by a nonlinear Michelson interferometer-based saturable absorber (NLI-SA), which acts as an intensity-dependent reflector, increasing reflectivity with signal intensity. The NLI-SA's reflectivity curve can be tuned to switch the laser between pulsed and continuous wave (CW) modes, offering flexibility for various applications such as laser surgery and LiDAR systems. The study demonstrates the potential of silicon photonics for high-energy, compact, and efficient laser applications.