Four-channel CWDM transmitter chip based on thin-film lithium niobate platform

Multi-lane integrated transmitter chips are key components in future compact optical modules to realize high-speed optical interconnects.Thin-film lithium niobate(TFLN)photonics have emerged as a promising platform for achieving high-performance chip-scale optical systems.Combining a coarse wavelength-division multiplexing(CWDM)devices using fabrication-tolerant angled multimode interferometer structure and high-performance electro-optical modulators,we demonstrate monolithic on-chip four-channel CWDM transmitter on the TFLN platform for the first time.The four-channel CWDM transmitter enables high-speed transmissions of 100 Gb/s data rate per wavelength channel(i.e.,an aggregated date rate of 400 Gb/s).

Anisotropy-free arrayed waveguide gratings on X-cut thin film lithium niobate platform of in-plane anisotropy

Arrayed waveguide grating is a versatile and scalable integrated light dispersion device,which has been widely adopted in various applications,including,optical communications and optical sensing.Recently,thin-film lithium niobate emerges as a promising photonic integration platform,due to its ability of shrinking largely the size of typical lithium niobate based optical devices.This would also enable multifunctional photonic integrated chips on a single lithium niobate substrate.However,due to the intrinsic anisotropy of the material,to build an arrayed waveguide grating on X-cut thin-film lithium niobate has never been successful.Here,a universal strategy to design anisotropyfree dispersive components on a uniaxial in-plane anisotropic photonic integration platform is introduced for the first time.This leads to the first implementation of arrayed waveguide gratings on X-cut thin-film lithium niobate with various configurations and high-performances.The best insertion loss of 2.4 dB and crosstalk of−24.1 dB is obtained for the fabricated arrayed waveguide grating devices.Applications of such arrayed waveguide gratings as a wavelength router and in a wavelength-division multiplexed optical transmission system are also demonstrated.

Bias-drift-free Mach–Zehnder modulators based on a heterogeneous silicon and lithium niobate platform

Optical modulators have been and will continue to be essential devices for energy-and cost-efficient optical communication networks.Heterogeneous silicon and lithium niobate modulators have demonstrated promising performances of low optical loss,low drive voltage,and large modulation bandwidth.However,DC bias drift is a major drawback of optical modulators using lithium niobate as the active electro-optic material.Here,we demonstrate high-speed and bias-drift-free Mach–Zehnder modulators based on the heterogeneous silicon and lithium niobate platform.The devices combine stable thermo-optic DC biases in silicon and ultra-fast electro-optic modulation in lithium niobate,and exhibit a low insertion loss of 1.8 d B,a low half-wave voltage of 3 V,an electro-optic modulation bandwidth of at least 70 GHz,and modulation data rates up to 128 Gb/s.

Four-channel CWDM device on a thin-film lithium niobate platform using an angled multimode interferometer structure

A compact and high-performance coarse wavelength-division multiplexing(CWDM) device is introduced with a footprint of 2.1 mm × 0.02 mm using an angled multimode interferometer structure based on a thin-film lithium niobate(TFLN) platform.The demonstrated device built on a 400 nm thick x-cut TFLN shows ultra-low insertion losses of <0.72 dB.Measured 3 dB bandwidths are 12.1 nm for all channels,and cross talks from adjacent channels are better than 18 dB.Its peak wavelength positions comply with the CWDM standard with a channel spacing of 20 nm.The filter bandwidth of the proposed CWDM device can be tuned by adjusting the structural parameters.This demonstrated CWDM device will promote future realization of multi-channel and multi-wavelength transmitter chips on TFLN.