Compact broadband suspended silicon photonic directional coupler

Directional couplers are extensively used in photonic integrated circuits as basic components for efficient on-chip photonic signal routing. Conventionally, directional couplers are fully encapsulated in the technology's waveguide cladding material. In this Letter, we demonstrate a compact broadband directional coupler, fully suspended in air and exhibiting efficient power coupling in the cross state. The coupler is designed and built based on IMEC's iSiPP50G standard platform, and hydrofluoric (HF) vapor-etching-based post-processing allows to release the freestanding component. A low insertion loss of 0.5 dB at lambda = 1560 nm and a 1 dB bandwidth of 35 nm at lambda = 1550 nm have been confirmed experimentally. With a small footprint of 20 mu m x 30 mu m and high mechanical stability, this directional coupler can serve as a basic building block for large-scale silicon photonic microelectromechanical systems (MEMS) circuits. (C) 2020 Optical Society of Americ

MEMS-enabled silicon photonic integrated devices and circuits

Photonic integrated circuits have seen a dramatic increase in complexity over the past decades. This development has been spurred by recent applications in datacenter communications and enabled by the availability of standardized mature technology platforms. Mechanical movement of wave-guiding structures at the micro- and nanoscale provides unique opportunities to further enhance functionality and to reduce power consumption in photonic integrated circuits. We here demonstrate integration of MEMS-enabled components in a simplified silicon photonics process based on IMEC's Standard iSiPP50G Silicon Photonics Platform and a custom release process

MEMS for Photonic Integrated Circuits

The field of microelectromechanical Systems (MEMS) for photonic integrated circuits (PICs) is reviewed. This field leverages mechanics at the nanometer to micrometer scale to improve existing components and introduce novel functionalities in PICs. This review covers the MEMS actuation principles and the mechanical tuning mechanisms for integrated photonics. The state of the art of MEMS tunable components in PICs is quantitatively reviewed and critically assessed with respect to suitability for large-scale integration in existing PIC technology platforms. MEMS provide a powerful approach to overcome current limitations in PIC technologies and to enable a new design dimension with a wide range of applications

Silicon photonic MEMS add-drop filter

We demonstrate a compact add-drop filter based on a MEMS ring resonator implemented in IMEC's iSiPP50G silicon photonics platform. The device exhibits a port extinction of 20 dB and a port isolation of > 50 dB, upon actuation range of 0 V to 27 V

Integration of MEMS in Silicon Photonics

Like integrated electronics, integrated photonics such as Silicon Photonics benefit from increased device-density on a single chip. Silicon is an excellent material for integrated photonics because its high refractive index allows devices to be made small, and the established silicon CMOS fabrication infrastructure provides a convenient route towards scaling up production. However, standard Silicon Photonics faces a bottleneck in scaling up device-density due to excessive power consumption and high optical losses associated with individual devices. Microelectromechanical systems (MEMS) provide a unique solution to this problem by providing a physical redistribution of optical media to perform the necessary active functions in photonic integrated circuits (PICs) with minimal power consumption and low loss. This thesis tackles two important aspects needed for implementing large-scale MEMS-enabled PICs in silicon. First, the required microfabrication processes are developed for the first-time, by full process integration of MEMS in an established foundry platform, the Interuniversity Microelectronic Centre's (IMEC) iSiPP50G Silicon Photonics technology. By demonstrating MEMS-compatibility, the barrier to adopting this new technology is reduced, and the devices and circuits themselves benefit from co-integration with high-performance standard components. Second, a new class of electrostatic MEMS-enabled photonic building blocks are designed, simulated, and experimentally characterized. Demonstrated devices include a set of remarkably broadband (bandwidth > 80 nm) tunable couplers capable of continuous optical power tuning between output ports to produce extinction ratios greater than 20 dB with minimal insertion loss (reaching < 0.4 dB). In terms of switching, a very low-voltage, six-port count device and a particularly compact (65 um x 62 um) photonic MEMS switch with sub-microsecond switching time are also presented. Further MEMS-enabled functionality is demonstrated with a wavelength-selective add-drop filter and a discussion of phase-shifters and multi-device sub-circuits. These components can be repeated and combined with one another to create complex and reconfigurable networks, and therefore represent an essential stepping stone towards the realization of very large-scale PICs. Together, these key developments in microfabrication and device design promise PIC designers MEMS-enabled photonic components as standard elements in their circuits to efficiently implement functions such as switching, tuning, and filtering for application in photonic switch matrices, weighted interconnects for neural networks, and programmable PICs

Silicon Photonic Broadband Suspended Directional Coupler

We demonstrate a broadband Silicon Photonic directional coupler that is entirely suspended in air. The device has been fabricated in a simplified Silicon Photonics process based on the standard IMEC ISIPP5OG platform, combined with custom post-processing including an HF vapor release step. The coupler exhibits a 1 dB bandwidth of 35 nm at lambda=1550 nm, and an insertion loss of 0.5 dB at 1560 nm, confirmed experimentally. With an extinction ratio of 25 dB at 1550 nm and a compact footprint of similar to 30 x 20 mu m(2), the coupler can serve as basis for a new generation of compact standard Silicon Photonic MEMS library components

Freestanding Silicon Photonic Ring and Disk Resonators

We report freestanding silicon photonic ring and disk resonators fabricated in a simplified silicon photonics process based on IMEC's iSiPP5OG standard platform that have been released by a custom MEMS post-processing step. Experimental results show high optical Q-factors up to 3.6x10(4) for both ring and disk resonators, and extinction ratios larger than 20 dB. These functional, freestanding resonators demonstrate the compatibility of MEMS processing within a silicon photonics platform and open the possibility for large-scale integration of more complex photonic devices

Forward stimulated brillouin scattering in free-standing waveguides on a silicon photonics platform

Stimulated Brillouin Scattering (SBS) is demonstrated on a standard active silicon photonics platform, the forward SBS gain and opto-mechanical coupling rates are calculated for two different rib waveguide geometries