High performance waveguide uni-travelling carrier photodiode grown by solid source molecular beam epitaxy

Abstract

The first waveguide coupled phosphide-based UTC photodiodes grown by Solid Source Molecular Beam Epitaxy (SSMBE) are reported in this paper. Metal Organic Vapour Phase Epitaxy (MOVPE) and Gas Source MBE (GSMBE) have long been the predominant growth techniques for the production of high quality InGaAsP materials. The use of SSMBE overcomes the major issue associated with the unintentional diffusion of zinc in MOVPE and gives the benefit of the superior control provided by MBE growth techniques without the costs and the risks of handling toxic gases of GSMBE. The UTC epitaxial structure contains a 300 nm n-InP collection layer and a 300 nm n ++ -InGaAsP waveguide layer. UTC-PDs integrated with Coplanar Waveguides (CPW) exhibit 3 dB bandwidth greater than 65 GHz and output RF power of 1.1 dBm at 100 GHz. We also demonstrate accurate prediction of the absolute level of power radiated by our antenna integrated UTCs, between 200 GHz and 260 GHz, using 3d full-wave modelling and taking the UTC-to-antenna impedance match into account. Further, we present the first optical 3d full-wave modelling of waveguide UTCs, which provides a detailed insight into the coupling between a lensed optical fibre and the UTC chip.

Integrated Wireless-Optical Backhaul and Fronthaul Provision Through Multicore Fiber

“…3 (a), (d) and (g), saturation effects occurred for squared photocurrent values higher than approximately 10 mA 2 (corresponding to an optical input power to the UTC of around 14.5 dBm). These saturation effects originated in the UTC and are likely to be due to either thermal or space-charge effects [12]. The UTC was biased with a voltage of -2 V as lower voltages did not improve the transmission performance.…”

Low Dark Current 1.55 Micrometer InAs Quantum Dash Waveguide Photodiodes

“…The bandwidth can be further improved by engineering the design of the epitaxial layers, reducing the device size, and applying traveling wave electrodes to better balance between the bandwidth and the quantum efficiency. 49…”

Design and Fabrication of sub-THz Steerable Photonic Transmitter 1×4 Array for Short-Distance Wireless Links

“…The measured leakage current was below 100 nA at 1 V of negative bias and the responsivity was 0.16 A/W. Powers of 32 μW and 60 μW (with respective photocurrents of 10 mA and 13.5 mA) were measured at 250 GHz from one of these UTCs mounted in a 6 mm diameter Si lens [21]. The lower-thanexpected output powers have been attributed to inaccurate modelling parameters [22] which have now been refined by experimental measurement for this newer design.…”

“…Compared to vertically illuminated UTCs, waveguide integrated PDs have shown to ease the strong responsivity-bandwidth trade-off found in the former and have produced record output powers [20]. The UTC epitaxial structure -detailed in [21] -contains a 300 nm n-InP collection layer and a 300 nm n++-InGaAsP waveguide layer.…”