Reconfigurable waveguide components are promising building blocks for photonic neural networks and as an optical analogue to field-programmable gate arrays. By changing the effective index of the waveguide, reconfigurable waveguide components can achieve on-chip light routing and modulation. In this paper, we design and demonstrate an Sb ₂ S ₃ -reconfigurable InP membrane Mach–Zehnder interferometer (MZI) on a silicon substrate. Sb ₂ S ₃ , which has tunable refractive index and low absorption in the near-infrared spectrum, was patterned on the InP waveguide MZIs to make an optical switch in the telecoms conventional-band. By laser induced crystallisation of the Sb ₂ S ₃ , it was possible to control interference in the MZI and achieve 18 dB on/off switching at 1540 nm. Laser reamorphisation and reversible switching of the Sb ₂ S ₃ layer resulted in damage to the waveguide structure. However, simulations show that transition metal di-chalcogenide two-dimensional crystal layers can act as efficient thermal barriers that prevent thermal damage to the waveguide during laser amorphisation. Therefore, combining Sb ₂ S ₃ with InP waveguides seems to be a feasible approach to achieve low-loss reprogrammable waveguide components for on-chip photonics routing and neural networks.

Optical beam steerers on InP integrated photonics have not been able to offer high angular resolution, due to the technological challenges in realizing a large emission aperture. In this paper, we propose the creation of waveguide-based grating antennas fabricated in SiO2 super-cladding on InP membrane on silicon (IMOS) to achieve simultaneously high resolution and good compatibility with InP-based active devices. By exploiting the high dry etch selectivity between SiO2 and InP, a tolerant fabrication process is proposed and demonstrated, allowing for high controllability in the process. Device parameters including buffer thickness and pitch have been explored to obtain an optimized design. A 2-mm long grating antenna is fabricated and shows a record narrow full-width-half-maximum angular beam width of 0.05° and a high spatial resolution of more than 250 points when the wavelength is tuned over a range of 100 nm.

In this work we have demonstrated a waveguide integrated uni-traveling carrier photodiode on an InP-membrane-on-silicon platform with 3 dB bandwidth beyond 110 GHz. With design optimization and an improved process, devices as small as $ \text{3}\times \text{2}\;\mu \text{m}^2$ are successfully realized. An electrical equivalent circuit model based on measured S-parameters revealed ultra-small series resistance and junction capacitance as low as 6.5 $\Omega$ and 4.4 fF, respectively, in the diodes. The model also provided insight in the photocurrent dependent characteristics in the bandwidth and resonsivity of the devices. Finally, data transmission measurements are demonstrated, showcasing the high speed telecommunication abilities of the UTC-PD.

We present waveguide photonic crystal reflectors on the InP-membrane-on-silicon (IMOS) platform, and a method to accurately measure the reflectivity of those reflectors. The photonic crystal holes are patterned on a waveguide using electron-beam lithography and etched through the waveguiding layer to create a broadband distributed Bragg reflector. We show simulations of these reflectors and experimental results of fabricated devices, both showing a high, free-to-choose reflectivity, and high quality factor Fabry-Pérot cavities. We experimentally show reflectivities higher than 95% for the reflectors and a quality factor as high as 15,911±511 for a Fabry-Pérot cavity, using reflectors with a length of only 4 microns. For the first time, to our knowledge, two methods for measuring the reflectivity are used for characterization of on-chip reflectors to accurately determine the reflection. The first method is based on analysis of the transmission through a Fabry-Pérot cavity, the second is based on a direct four-port measurement of the reflector. A systematic error is made in both methods, resulting in an upper and lower boundary for the actual reflection coefficient.

In this paper, an on-chip optical circulator on the InP-membrane-on-Si (IMOS) platform is demonstrated. The circulator is composed of two multi-mode interferometers (MMIs), four polarization converters (PCs), and a Cerium-doped Yttrium Iron Garnet (Ce:YIG) die. The Ce:YIG die is adhesively bonded on the InP membrane via a 125-nm thin bonding layer. Nonreciprocal phase shift (NRPS) is employed in the presence of a transverse magnetic field. The device works as a 4-port optical circulator with a maximum optical isolation of 27.0 dB and a minimum optical isolation of 18.6 dB for the TE mode. The measured optical isolation bandwidth is 0.12 nm. Two methods are proposed in order to improve the optical isolation bandwidth.

We present a characterization method for polarization converters which improves the accuracy of traditional characterization methods significantly. An experimental demonstration of the method is presented on the InP-membrane-on-silicon (IMOS) platform. The design and fabrication of the polarization converter is discussed, as well as the simulated polarization conversion efficiency. A device of only 4 microns is shown to achieve 97.5%±0.5% polarization conversion, corresponding to an extinction ratio of -16± 0.9 dB. The traditional characterization method is compared to the new 4-port method, and the accuracy is improved from up to 20% to 0.5%.