Indium-phosphide membrane on silicon is a nanophotonics platform which allows for monolithic integration of sub-micron nanophotonic waveguide circuits with native and efficient amplifiers and lasers. Active devices such as amplifiers have a high topography that requires a thick dielectric layer for planarization and wafer bonding, which poses challenges in thermal dissipation. Herein, we comprehensively analyzed the performance of distributed feedback lasers (DFBs) bonded on Si using a 2 mu m-thick benzocyclobutene (BCB) layer, and with and without a 5 mu m-thick gold thermal shunt to the substrate for efficient thermal dissipation. The thermal resistance of shunted devices is 176 and 115 K W-1 for 0.5 mm and 0.75 mm lengths, respectively, which is a 2x improvement compared to reference membrane devices with no thermal shunt. This thermal resistance is maintained across various BCB thicknesses up to 30 mu m, ensuring the possibility of using such devices for scalable 3D integration on other platforms or with electronics. Moreover, we showed that the thermal resistance value is around 110-120 K W-1 for 0.75 mm-long shunted DFBs having array density values in the range of 40-200 mu m, and that the temperature rise at the end of the DFB contact is as low as 1.3 degrees C at 8 kA cm-2 driving current. Both of these characteristics demonstrate the density scaling potential of these nanophotonic devices.

We experimentally demonstrate an efficient TM0 filter on InP membrane. The filter exhibits an extinction ratio exceeding 34 dB for TM0 and a loss lower than 0.5 dB for TE0 at 1570 nm.

Managing insertion losses, polarizations and device footprint is crucial in developing large-scale photonic integrated circuits (PICs). This paper presents a solution to these critical challenges by designing a semiconductor optical amplifier (SOA) in the O-band with reduced polarization sensitivity, leveraging the ultra-compact InP Membrane on Silicon (IMOS) platform. The platform is compatible with close integration atop electronics, via densely populated vertical interconnects. The SOA incorporates a thin tensile-strained bulk active layer to mitigate polarization sensitivity. The developed 500 um long SOA has a peak gain of 11.5 dB at 1350 nm and an optimal polarization dependency of less than 1 dB across a 25 nm bandwidth, ranging from 1312 nm to 1337 nm. The device is practical for integrated circuits where multiple amplifiers work in cascades with a minimal 6.5 dB noise figure (NF) measured at the gain peak. The designed vertical active-passive transition, achieved through inverse tapering, allows for effective field coupling in the vertical direction resulting in a transmission efficiency of over 95% at the transition and minimal polarization sensitivity of less than 3%. The device yields significant gain at a small current density of less than 3 kA/cm2 as the result of minimalist gain medium structure, reducing joule heating and improving energy efficiency. This is especially relevant in applications such as optical switching, where multiple SOAs populate the PIC within a small area. Consequently, the simulated and fabricated low polarization sensitive O-band SOA is a suitable candidate for integration into large-scale, ultra-compact photonic integrated circuits.

Optical switches (OS) are vital for meeting modern data centers' capacity and latency needs, overcoming the bandwidth and speed limitations that electronic switches encounter. To this end, this work proposes a semiconductor optical amplifier (SOA)-based OS on the IMOS, a unique platform with a combination of high refractive index contrast for compactness and monolithic active-passive integration for active functionalities, thereby enabling the creation of compact SOA-based OSes. An 8 x 8 Banyan SOA-based OS is integrated on a 4 x 4 mm2 area on the standard 4 x 6 mm2 IMOS cell. This marks the first application of the IMOS technology platform for SOA-based OSes and sets the stage for compact and large-scale monolithic photonic integrated OS circuits. The basic 2 x 2 switch module delivers a high optical signal-to-noise ratio (OSNR) and an extinction ratio (ER) above 45 dB. Employing NRZ-OOK routing on the 2 x 2 basic OS module, a 15 dB input power dynamic range (IPDR) is achieved within a 1 dB power penalty at 12.5 Gb/s. Data routing at higher data rates of 25 Gb/s and 40 Gb/s incurs power penalties of 0.8 and 1.4 dB, respectively. Furthermore, data routing for a 3-stage 8 x 8 switch operating at 25 Gb/s results in a power penalty of 1.2 dB. Compared to the 1-stage 2 x 2 switch, only a 0.4 dB additional penalty is observed despite incorporating 2 additional SOAs in the cascade. This indicates that the switch can scale to higher radix to accommodate multi-stage switches with numerous ports, large bandwidth, and fast speed, which is essential in modern large-scale data centers. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

We report a versatile method for improving post-bonding wafer alignment accuracy and BCB thickness uniformity in stacks bonded with soft-baked BCB. It is based on novel BCB-based micro-pillars that act as anchors during bonding. The anchor structures become a natural part of the bonding interface therefore causing minimal interference to the optical, electrical and mechanical properties of the bonded stack. We studied these properties for fixed anchor density and various anchor heights with respect to the adhesive BCB thickness. We demonstrated that the alignment accuracy can be improved by approximately an order of magnitude and approach the fundamental pre-bond alignment accuracy by the tool. We also demonstrated that this technique is effective for a large range of BCB thicknesses of 2-16 µm. Furthermore we observed that the thickness non-uniformities were reduced by a factor of 2-3x for BCB thicknesses in the 8-16 µm range.

Herein we present a novel method to improve the post-bonding alignment accuracy of substrates assembled via adhesive bonding with Benzocyclobutene (BCB). The method relies on hard BCB anchors to block misalignment. As a result, the alignment accuracy has been improved by an order of magnitude for a wide range of bonding BCB thicknesses (2-16 µm) without influencing the continuity of this adhesive layer.

We propose a novel co-packaged optical transceiver architecture capable of operating at 112 Gbaud per lane and scalable to 1.6 Tb/s capacity and beyond for next generation 51.2T and 102.4T digital switches.

Electron Beam Lithography (EBL) metrology and least-square estimation of wafer-scale distortions is used to determine InP membrane deformation as a result of bonding to different substrate materials. First, the accuracy of EBL as a metrology tool for this particular application was assessed. Next, modelling of distortions was tested on unbonded InP wafers as a reference for extracting post-bonding distortions. Then we investigated the effect of substrate material choice on InP membrane deformation after bonding. We found residual expansion factors of 4.53±1, 312.4±1, and 317±1 ppm of the InP membrane bonded to InP, Si, and 3C-SiC carriers, respectively. For the SiO 2 carrier, the 3inch InP membrane split into smaller membranes to reduce the stress, highlighting the importance of substrate choice.