Search Results (2)

Spectrally flat-topped and polarization-insensitive coarse wavelength division multiplexing (CWDM)-targeted optical demultiplexers based on distributed multimode-interference (MMI) phase compensations are analytically calculated and experimentally demonstrated. The proposed device for use in a CWDM optical receiver consists of a polarization splitter-rotator (PSR) and two identical silicon-nanowire multiple delayed interferometric (MDI) demultiplexers. The broadband operating nature of MMI couplers is highly suitable for applying the proposed device to >60 nm wide CWDM applications. Moreover, by properly adjusting the relative output phase relations of MMI couplers according to their optical splitting ratios, we experimentally validated a flat-topped CWDM spectral response within the O-band spectral range. Concurrently, stable optical demultiplexing operations were maintained regardless of the input signal polarization states via the monolithically integrated PSR. Fabricated using a silicon photonics foundry process based on ArF-dry lithography technology, the devices exhibited a 1 dB flat bandwidth of >12 nm, a polarization-dependent loss of <1.0 dB, an adjacent-channel isolation of >10 dB, and a polarization crosstalk of <−20 dB across the measured output channels. Although the current spectral crosstalk is ~−10 dB, it can be further suppressed to the −20 dB level through fabrication process optimization to minimize random phase fluctuations, or by incorporating a double-filtering scheme. This distributed MMI phase compensation strategy can be broadly applied to scalable WDM architectures in datacom applications. Full article

Integrated optical isolators are important building blocks for photonic integrated chips. Despite significant advances in isolators integrated on silicon-on-insulator (SOI) platforms, integrated isolators on GaAs-on-insulator platforms are rarely reported. In this paper, two structural designs of optical isolators based on the TM basic mode of GaAs-on-insulator are proposed. The non-reciprocal phase shift (NRPS) of GaAs/Ce:YIG waveguides with different geometric structures are calculated using numerical simulation. The isolators achieve 35 dB isolation bandwidths greater than 53.5 nm and 70 nm at 1550 nm, with total insertion losses of 2.59 dB and 2.25 dB, respectively. A multi-mode interferometric (MMI) coupler suitable for these two structures is proposed. In addition, suitable manufacturing processes are discussed based on the simulated process tolerances. Full article