Emulation of deep-ultraviolet lithography using rapid-prototyping, electron-beam lithography for silicon photonics design.

We demonstrate a method to emulate the optical performance of silicon photonic devices fabricated using advanced deep-ultraviolet lithography (DUV) processes on a rapid-prototyping electron-beam lithography process. The method is enabled by a computational lithography predictive model generated by processing SEM image data of the DUV lithography process. We experimentally demonstrate the emulation method's accuracy on integrated silicon Bragg grating waveguides and grating-based, add-drop filter devices, two devices that are particularly susceptible to DUV lithography effects. The emulation method allows silicon photonic device and system designers to experimentally observe the effects of DUV lithography on device performance in a low-cost, rapid-prototyping, electron-beam lithography process to enable a first-time-right design flow.

Contra-directional pump reject filters integrated with a micro-ring resonator photon-pair source in silicon.

High coincidence-to-accidental ratio (CAR) is crucial for photon-pair sources (PPSs) integrated with pump reject filters (PRFs) in silicon, but CAR values currently reported for integrated PPS/PRF chips still fall short of those achieved using stand-alone sources with external PRFs. Here we report measured and modelled CAR values for a micro-ring resonator PPS integrated with a PRF consisting of a three-stage, cascaded (via their through ports), contra-directional coupler (CDC) that compare favorably even with some stand-alone sources. CDC-based PRFs provide the benefits of compact area and wide reject bands without a need for tuning, in comparison to prior-art implementations.

Broadband, silicon photonic, optical add-drop filters with 3 dB bandwidths up to 11 THz: publisher's note.

This publisher's note contains corrections to Opt. Lett.46, 2738 (2021)OPLEDP0146-959210.1364/OL.423745.

Broadband, silicon photonic, optical add-drop filters with 3 dB bandwidths up to 11 THz.

We present the designs, theory, and experimental demonstrations of ultra-broadband, optical add-drop filters on the silicon-on-insulator platform, realized using period-chirped contra-directional couplers. Our fabricated devices have ultra-broad 3 dB bandwidths of up to 11 THz (88.1 nm), with flat-top responses at their drop ports. All of our devices were fabricated using a commercial, CMOS-compatible, 193 nm deep-ultraviolet lithography process. By using lithography-prediction models, the measured bandwidths, insertion losses, central wavelengths, and extinction ratios of our devices are all in good agreement with our predicted, simulated results. Such filters are necessary for photonic integrated circuits to operate over multiple optical bands.

Broadband flat-top SOI add-drop filters using apodized sub-wavelength grating contradirectional couplers.

We report on broadband, flat-top, optical add-drop filters using apodized, sub-wavelength grating contradirectional couplers (SWG CDCs) on a silicon-on-insulator platform. In our device, two asymmetric SWG waveguides, having corrugation-apodized Bragg gratings, are used to couple light contradirectionally between the fundamental and next higher-order transverse electric modes of a two-waveguide system. We demonstrate an apodized, SWG CDC that has a flat-top, drop-port response with a 3 dB bandwidth of 32.6 nm, a sidelobe suppression ratio of 19 dB, and a low excess loss of 0.26 dB. We also demonstrate series-cascaded, apodized, SWG CDCs that have square-shaped, drop-port responses with 3 dB bandwidths >30 nm, sidelobe suppressions >50 dB, and low excess losses <0.85 dB.

Compact, silicon-on-insulator, series-cascaded, contradirectional-coupling-based filters with >50 dB adjacent channel isolation.

In this work, we present optical add/drop multiplexer (OADM) filters for coarse wavelength-division-multiplexing (CWDM) systems with high sidelobe suppressions that result in high adjacent channel isolations (Ai). The filters are realized by using a compact, series-cascaded configuration of apodized, contradirectional-coupling-based filters. We experimentally demonstrate a device with a measured Ai of 53 dB (these devices hold the promise of achieving even higher Ais). While having large Ais, our devices have the wide bandwidths and low insertion losses required for CWDM applications. In addition, our demonstrated OADM has a nearly constant group delay, which results in low dispersion in the passband.

Bandwidth-tunable, FSR-free, microring-based, SOI filter with integrated contra-directional couplers.

A silicon-on-insulator (SOI), bandwidth (BW)-tunable, free-spectral-range (FSR)-free, microring resonator (MRR)-based filter is experimentally demonstrated. The device achieves an FSR-free response at its through and drop ports by using a grating-assisted coupler in one coupling region of the MRR and achieves a non-adjacent channel isolation, (nAi), for 400 GHz WDM, greater than 26.7 dB. A thermally tunable Mach-Zehnder Interferometer-based coupling scheme is also utilized to compensate for fabrication variations and enable the BW tunability of the filter. The BW of the filter can be continuously tuned from 25 to 60 GHz while maintaining an nAi greater than 26.7 dB.