InP DFB lasers are flip-chip bonded to 300mm Si photonic wafers using a pick-and-place tool with an advanced vision system, realizing high-precision and high-throughput passive assembly. By careful co-design of the InP-Si Photonics electrical, optical and mechanical interface, as well as dedicated alignment fiducials, sub-300nm post-bonding alignment precision is realized in a 25s cycle time. Optical coupling losses of -1.5±-0.5dB are achieved at 1550nm wavelength after epoxy underfill, with up to 40 mW of optical power coupled to the SiN waveguides on the Si photonics wafer. The bonding interface adds less than 10% to the series resistance of the laser diodes and post-bonding thermal resistance is measured to be 76K/W (or 27K.mm/W), mostly dominated by heat spreading resistance in the InP lasers as suggested by in-depth thermal modeling. Although the assembled lasers suffer from significant, unintentional optical backreflection from the fiber grating couplers used for optical characterization, laser linewidths well below 1MHz have been measured under specific drive conditions, as supported by a detailed laser noise analysis. Finally, we demonstrate the ability of bonded laser assemblies to pass early reliability tests.

Optical phase errors are inherent to practical waveguides and will degrade the beam quality of optical phased arrays. This paper demonstrates a scalable approach to on-chip phase calibration of optical phased arrays using a compact phase interrogator structure. This phase interrogator is designed for optical phased arrays with a 2.5μm pitch and demonstrated in a 64-channel optical phased array realized in a Si/SiN photonic stack. The optical phased array exhibits 38° of unambiguous beam steering range and a side lobe level of at most -9.8 dB after calibration. The calibration algorithm is model-based and does not rely on any iterative optimization algorithm. This enables calibration with linear scaling of both the computational complexity and the area of the calibration structures. By including wavelength dependent effects, the model allows for 2D beam steering without any need for re-calibration.

In the current work we present Si and SiN combined photonic built-up for optical phased arrays (OPAs) and other large area photonic integrated circuits. We report low-loss co-integrated SiN waveguides and nearly lossless vertical transitions between Si and SiN layers, as well as efficient Si thermo-optical phase shifter module. OPA consisting of 64 optical antennas forming highly collimated beam with 0.4° × 0.47° divergence is reported. By changing input wavelength, solid-state beam steering of 0°–10° is achieved.

WA detailed thermal analysis of a hybrid, flip-chip InP-Si DFB laser is presented in this work. The lasers were experimentally tested at different operating temperatures, which allowed for deriving their thermal performance characteristics: the temperature dependence of threshold current, lasing slope, and output spectrum. Using these data, the laser thermal resistance was calculated (R_th = 75.9 K/W), which allows for predicting the laser temperature during operation. This metric is also used to validate the thermal finite element models of the laser. A sensitivity study of the laser temperature was performed using these models, and multiple routes for minimising both the laser thermal resistance and thermal coupling to the carrier die are presented. The most effective way of decreasing the laser temperature is the direct attachment of a heat sink on the laser top surface.

Integrated polymer photonics brings low cost and high fabrication flexibility to optoelectronic industry. However, this platform needs to overcome several issues to be effective enough for practical applications. In this work, we experimentally demonstrate a decrease of propagation losses and polarization sensitivity of polymer waveguide-based devices as a result of thermal treatment. Heating of poly(methyl methacrylate) strip optical waveguides above the glass transition temperature initiates a waveguide surface reflow due to a decrease of the polymer viscosity and surface tension energy. This results in a decrease of surface roughness and shape change from rectangular to cylindrical. Thus, scattering losses and polarization sensitivity are minimized.