In this article, a high-efficiency grating coupler based on a lithium niobate platform is presented. To enhance the coupling efficiency, a silicon nitride strip waveguide grating is introduced beneath the lithium niobate grating. Through the optimization of grating period, duty cycle, and other parameters using a particle swarm optimization (PSO) algorithm, a TE-polarized grating coupler with high coupling efficiency is achieved, resulting in a simulated peak coupling efficiency of approximately -2.19 dB. To further improve the performance of the grating coupler, a chirped design of the grating etch slots is implemented. A double-layer design with inversely linear variation in duty cycle is adopted, and the variation coefficients are optimized using the PSO algorithm, achieving a simulated peak coupling efficiency of approximately -1.72 dB with a 1 dB bandwidth of approximately 42 nm. Process tolerance simulations are also performed on the key parameters of the double-layer grating coupler, demonstrating good process tolerance of this design.
Applying various functional materials to silicon to enhance the functionality of silicon photonics is a potential solution for silicon photonics platform under the requirement of CMOS compatibility. In this paper, two LN heterogeneous integration platforms have been proposed. One is the integration of LN film with a 220 nm top silicon SOI platform, in which the simulated results demonstrate that the designed modulator has a low half wave-voltage length product of 2.27 V·cm. And the other is the integration of LN film with a 400 nm top silicon nitride on insulator platform, in which the the proposed device achieves a VpiL of 2.58 V·cm and a 3-dB bandwidth of ~130 GHz with 7-mm long modulation region is verified by simulation.
A polarization-insensitive four-channel wavelength-division multiplexing (WDM) (de)multiplexer based on Mach-Zehnder interferometers is proposed and demonstrated. Polarization insensitivity can be achieved by utilizing the square waveguides and bend directional couplers (bend DCs) based on silicon oxynitride (SiON) waveguides. The WDM (de)multiplexer has an 800GHz spacing for LAN-WDM application. Two stages of cascaded MZIs are utilized to achieve a four-channel spectral response. For the realized WDM (de)multiplexer with Gaussian-like passbands, the polarization-dependent losses (PDL) are less than 0.7dB for all 1-dB passbands. The insertion losses are <~ 3dB and the crosstalk is <~ -12dB for both TE and TM polarizations at channel central wavelengths.
The 3D photonic integrated structure can increase the integration density of the device on a limited chip area, so that the chip has a higher optical interconnection capability. A polarization beam splitter (PBS) is one of the key components for manipulating different polarization states in the areas of optical interconnection and communication. In this paper, a novel interlayer PBS based on an asymmetrical directional coupler (DC) was proposed, which consists of a silicon rib waveguide (WG) and a silicon nitride (Si3N4) strip WG with a gap of 850 nm. By carefully adjusting the geometric parameters of the DC, the phase matching condition between these two WGs can be satisfied for the TM polarization, while the coupling efficiency of the TE polarization is frustrated due to the large phase mismatch. By adding a filter to the thru port the performance of the proposed PBS is improved. The device with a 220 nm Silicon-On-Insulator (SOI) WG and a 700 nm × 400 nm Si3N4 WG operates in a broadband width of 100 nm, with an extinction ratio (ER) <20 dB. The insertion losses (ILs) are <0.22 dB for both TE and TM polarizations at a wavelength of 1550 nm. At the same time, our design parameters conform to the Multi Project Wafer (MPW) process conditions, and the device is highly implementable. The device is potential to use for the on-chip 3D optical interconnect in the future.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.