Intracavity-SHG telecom modelocked oscillator for compact quantum homodyne detection.

We demonstrate a compact telecom-wavelength modelocked laser source designed for pumping spontaneous parametric downconversion (SPDC), based on an erbium-ytterbium co-doped phosphate glass laser with intracavity second harmonic generation (SHG) to 773.5 nm. Using a 0.4 mm thick β-barium borate crystal, the system produces nearly 35 mW of average power with 191 fs pulses at 773.5 nm. This represents a 1000-fold increase in average power compared to previously reported intracavity SHG modelocked fs-level telecom oscillators (C. Hu, Y. Zhang, Q. Gao, et al., Jap. J. of App. Phys.59080902 (2020)10.35848/1347-4065/aba37c). This architecture provides a path toward homodyne detection of SPDC-generated single photons using a phase-coherent local oscillator derived from the same cavity.