Invention cost-efficiently combines optical lasers, high-speed detectors and modulators onto high-performing telecommunications chip
UCF researchers have designed and developed a low-cost way to combine optical devices onto a compact, stable integrated chip that operates over octave-spanning or multi-octave spectral windows. The invention provides the telecommunications industry with a new photonics platform produced using a unique, repeatable manufacturing method that yields wafer-scale systems with extremely low propagation losses and a wide transparency window.
The telecommunications industry depends on high-performing, reliable and affordable photonic devices, such as low-noise lasers, high-speed detectors, and modulators to expand digital networks. Companies typically use separate devices connected through expensive and sensitive packaging operations. Though alternative monolithic, integrated solutions exist, they incur high material costs, are difficult to fabricate, or have poor performance and reliability. In contrast, the UCF invention offers a solution for integrating devices onto a chip without using complicated or time-consuming fabrication steps. The invention greatly improves the thermal management of compact optical devices and reduces power consumption needs, resulting in longer lifetimes, higher speeds, and lower cost-of-ownership.
The UCF invention comprises an integrated photonics structure and fabrication methods. The structure is a robust, efficient platform for building high-speed, high-quality optical devices. For example, as shown in Figure 1, the structure can consist of semiconductor layers stacked on top of a substrate of bulk semiconductor material. One or more trench-like openings, separated by posts, serve to isolate part of the stack from the underlying substrate, forming a suspended semiconductor membrane. The semiconductor membrane is an optically active layer that defines a waveguiding region, such as a multiple quantum well or a two-dimensional electron gas channel. The region confines an optical mode to the center of the semiconductor stack. Manufacturers can also implant the layers with p-type or n-type dopants. The resulting structure resolves issues of conventional integrated photonic devices, such as thermal insulation, elevated temperatures at the laser junction, and bulky active regions.
To produce the platform, manufacturers can use various techniques, shown in the following examples: (Sketches for the examples below are available in the online image gallery for this tech summary.)
Example 1: One method uses a donor substrate to epitaxially grow a quantum heterostructure on a planar semiconductor membrane (the active layer). The layer is transferred from the donor substrate and bonded onto a new substrate pre-patterned with two openings. The donor wafer has an etch-stop layer for precise removal of the backside etch, leaving a thin membrane with the heterostructure.
Example 2: Another method bonds a donor substrate onto a pre-patterned substrate. The substrate is then thermally sliced to form a seed layer for epitaxially growing the quantum heterostructure.
Example 3: The invention enables many geometric arrangements for the optical waveguide mode: In (a) an etched ridge confines the optical mode. In (b), a “post” confines the optical mode.
Example 4: In an embodiment, the laser heterostructure in the suspended membrane emits photons at a specific wavelength when an electrical current crosses the P and N contacts.
- Scalable, simple, reliable and easily repeatable low-cost manufacturing method
- Boosts performance in harsh environments and provides greatly improved thermal management
- Reduces power consumption and increases operational lifetimes
- Integrated lasers, modulators or high-speed optical detectors that operate in the 1.55 µm wavelength