High-quality integrated diamond photonic devices have previously been demonstrated in applications from non-linear photonics to on-chip quantum optics. However, the small sample sizes of single crystal material available, and the difficulty in tuning its optical properties, are barriers to the scaling of these technologies. Both of these issues can be addressed by integrating micrometer-scale diamond devices onto host photonic integrated circuits using a highly accurate micro-assembly method. In this work a diamond micro-disk resonator is integrated with a standard single-mode silicon-on-insulator waveguide, exhibiting an average loaded Q-factor of 3.1×104 across a range of spatial modes, with a maximum loaded Q-factor of 1.05×105. The micrometer-scale device size and high thermal impedance of the silica interface layer allow for significant thermal loading and continuous resonant wavelength tuning across a 450 pm range using a milliwatt-level optical pump. This diamond-on-demand integration technique paves the way for tunable devices coupled across large-scale photonic circuits.

Passive mode-locking in semiconductor lasers in a Fabry–Perot configuration with a bandgap blueshift applied to the saturable absorber (SA) section has been experimentally characterized. For the first time a fully post-growth technique, quantum well intermixing, was adopted to modify the material bandgap in the SA section. The measurements showed not only an expected narrowing of the pulse width but also a significant expansion of the range of bias conditions generating a stable train of optical pulses. Moreover, the pulses from lasers with bandgap shifted absorbers presented reduced chirp and increased peak power with respect to the nonshifted case.