Multi-Pass Optical Parametric Amplifier for Broad Gain Bandwidth

The patent divides the amplification process into multiple passes through a shorter crystal rather than using a single long crystal. The amplifier crystal is traversed multiple times in different directions, with each pass contributing to the overall conversion efficiency while the multi-pass geometry maintains broad spectral bandwidth.

The patent introduces spatial dimensionality by using a multi-pass geometry with mirrors arranged to guide light through the crystal in multiple directions. This transforms the problem from a one-dimensional length issue to a multi-dimensional spatial arrangement, achieving high efficiency without requiring increased crystal length.

The patent designs the amplifier crystal and mirror arrangement to serve multiple functions simultaneously: the same crystal and mirrors handle both phase matching for different wavelengths and the amplification process. The system achieves wide spectral coverage without requiring separate adjustment mechanisms for different wavelength ranges.

The patent employs a pump-probe configuration where the pump beam automatically establishes the phase matching conditions for the signal and idler beams. The system self-adjusts to different wavelengths through the nonlinear optical properties of the crystal without requiring external mechanical adjustment of multiple elements.

The patent segments the total interaction length into multiple passes through a shorter crystal. Each pass provides a portion of the total gain, and the cumulative effect of multiple passes achieves high overall gain while maintaining the short crystal length necessary for broad bandwidth.

The patent ensures continuous amplification by arranging multiple passes through the crystal, where the signal beam interacts with the pump beam in each pass. This continuous interaction across multiple passes accumulates gain without interruption, achieving high gain with a short crystal.