New Technology Offers Thin-Film Integration Compatible with Silicon Photonics Foundry Production

Technology #33647

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Figure 1. Example method of fabricating a device using the inventionFigure 2. Example embodiment of the invention shows a BEOL heterogeneous integration of lithium niobate modulators and silicon photonicsFigure 3. Example of the ability to vertically transmit the mode into the modulator via rib-loaded optical waveguides.
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Researchers
Sasan Fathpour, Ph.D.
External Link (www.creol.ucf.edu)
Amirmahdi Honardoost
External Link (www.creol.ucf.edu)
Saeed Khan
External Link (www.creol.ucf.edu)
Managed By
John Miner
Assistant Director 407.882.1136
Patent Protection

US Patent Pending

Invention can dramatically improve the efficiency and reliability of analog integrated photonic systems for high-speed telecommunications in the 1.55 μm wavelength regime

UCF researchers have invented a novel way to produce heterogeneous photonic integrated circuits using fabrication methods that are compatible with photonics foundry production. The new process enables manufacturers to incorporate thin-film lithium niobate (LiNbO3) high-speed modulators onto silicon (Si) chips to support high-performance analog photonic applications. Design libraries for foundry high-volume production provide an opportunity to apply an economy of scale to photonics and to market inexpensive, complex and functional photonic integrated circuits (PICs). However, the prevailing silicon photonics and indium phosphide (InP) PICs do not offer high-performance analog signal processingparticularly, reliable, linearized and compact analog optical modulators with broad bandwidth operation. Thus, most radio frequency photonic systems still rely on commercial off-the-shelf bulky LiNbO3 modulators. As a solution, the new UCF technology enables manufacturers to produce a hybrid thin-film LiNbO3 platform for integrated analog photonic applications. The new platform offers better analog system performance with standard integrated photonic circuits. Additionally, the following fabrication techniques enable compatibility with silicon photonic foundry production methods:

  • Integration of LiNbO3 occurs at the back end of line (BEOL) foundry integrated circuit fabrication process
  • Methods to connect LiNbO3 and Si compact modulators enables the optical mode to transfer between them with superior results
  • Low-cost fabrication method involves cleaving for LiNbO3

Technical Details

The invention consists of a platform technology for an analog photonic integrated circuit and fabrication methods for hybrid integration of LiNbO3 devices with silicon photonic devices. The novel scheme relies on bonding a thin-film of LiNbO3 on top of a prefabricated silicon photonic chip. The process also includes vertical coupling between SOI optical waveguides and LiNbO3 slab layers via silicon nitride (Si3N4 or SiN) with tapered ends. The lateral confinement of LiNbO3 waveguides is achieved by rib-loading the devices with a refractive index matching material and placing the ribs underneath the LiNbO3 slab to facilitate the optical flow between the Si and LiNbO3 regions.

Benefits

  • Smaller, cheaper and faster than commercially available products
  • Uses industry standard manufacturing methods
  • Higher speeds and smaller form factor increase the number of applications that use the technology

Applications

  • Integrated photonic circuits and foundries
  • Optical sensors
  • High-speed telecommunications in the 1.55 μm range