High-performance lithium-niobate-on-insulator optical filter based on multimode waveguide gratings

Abstract

A high-performance optical filter is proposed and realized with multimode waveguide grating (MWG) and two-mode multiplexers on the x-cut lithium-niobate-on-insulator (LNOI) platform for the first time, to the best of our knowledge. The present optical filter is designed appropriately to avoid material anisotropy as well as mode hybridness, and has a low excess loss of 0.05 dB and a high sidelobe suppression ratio (SLSR) of 32 dB in theory with Gaussian apodization. The fabricated filters show a box-like response with 1-dB bandwidth of 6–23 nm, excess loss of ∼0.15 dB, sidelobe suppression ratio of >26 dB. The device performance is further improved with a sidelobe suppression ratio as high as 48 dB and a low excess loss of ∼0.25 dB by cascading two identical MWGs.

First Realization of a Three-Channel Lithium-Niobate Photonic Filter for 50G Passive Optical Networks

“…The performance can be further improved by cascading more than one stage. 23 In summary, the proposed device has shown very excellent performance.…”

“…Figure 8a shows the normalized spectral The crosstalk between the two channels of 1270/1300 nm is as low as ∼−30 dB and the channel crosstalk can be reduced to −50 dB by cascading more than one MWG at the drop port. 23 The measured SLSR for the channel at 1342 nm is about 20 dB.…”

“…More recently, we demonstrated a high-performance singlechannel photonic filter by utilizing a MWG with Gaussian apodization on the X-cut LNOI platform, 23 exhibiting a boxlike response with low excess loss of ∼0.15 dB, a large 1 dB bandwidth of 6−23 nm, and a high sidelobe suppression ratio (SLSR) of ∼26 dB (even ∼48 dB when cascaded). This provides an effective solution for further realizing multichannel photonic filters.…”

Perspective on Lithium-Niobate-on-Insulator Photonics Utilizing the Electro-optic and Acousto-optic Effects

“…However, this AMMI-based multiplexer operates without a flat-top spectral response and has a very large size. As an alternative, an LNOI optical filter based on the combination of multimode waveguide gratings (MWGs) and mode (de)­multiplexers has been proposed with a box-like response and high sidelobe suppression ratio (SLSR) . Progress has also been made in capacity expansion with PDM.…”

“…As an alternative, an LNOI optical filter based on the combination of multimode waveguide gratings (MWGs) and mode (de)multiplexers has been proposed with a box-like response and high sidelobe suppression ratio (SLSR). 44 Progress has also been made in capacity expansion with PDM. Integrated with high-performance polarization rotators and combiners (PRCs), a dual-polarization IQ modulator presents a single-wavelength 1.96-Tb/s net data rate with ultrahigh energy efficiency of 1.04 fJ/bit.…”