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We present the development of Ag/Ge based ohmic contacts to n-type InP with both low contact resistances and relatively low optical losses. A specific contact resistance as low as 1.5×10 −6 Ω cm 2 is achieved by optimizing the Ge layer thickness and annealing conditions. The use of Ge instead of metal as the first deposited layer results in a low optical absorption loss in the telecommunication wavelength range. Compared to Au based contacts, the Ag based metallization also shows considerably reduced spiking effects after annealing. Contacts with different lengths are deposited on top of InP membrane waveguides to characterize the optical loss before and after annealing. A factor of 5 reduction of the propagation loss compared to the conventional Au/Ge/Ni contact is demonstrated. This allows for much more optimized designs for membrane photonic devices.

An automatic method to discriminate between adiabatic and transient-chirp dominated directly modulated semiconductor lasers (DML), useful to classify telecommunications transmitters, is presented. It is based on calculating the crosscorrelation between the optical power and chirp waveforms of the device under test and the use of a decision threshold. The accuracy of the algorithm is demonstrated using simulated signals obtained from a well-tested laser model complemented with experimentally-derived parameters for several real lasers. By modifying the confinement factor, the laser chirp behavior can gradually be transformed from transient to adiabatic, thus enabling the validation of the proposed algorithm. Correct classification results are reported. Due to its flexibility, ease of implementation, simplicity and accuracy, the classification algorithm here put forward, represents a practical tool for testing and fabrication of DMLs.

We present experimental studies of semiconductor optical amplifiers with a high integration density in an InP generic photonic integration platform. We study the activepassive butt-joint integration of dense arrays of active islands with widths ranging from 2 to 30 µm, and pitches ranging from 4 to 270 µm. We show that reducing the active island width from 20 µm to 4 µm enables a decrease of pitch by almost 4 times while keeping a similar growth rate enhancement (GRE) in between the active islands. The impact of narrow active islands on amplifier performance is also studied with an array of Fabry-Pérot lasers fabricated in a commercial generic platform. We demonstrate the manufacturability of lasers with a pitch of 25µm and evaluate individual device performance. Threshold currents and slope efficiencies are not impaired with narrow active island down to 6 µm, with values of 19-26 mA and 0.08-0.15 W/A respectively.