Planar Lightwave Circuits (PLC)
Physical and optical properties of Silica-on-Si waveguides are well controlled during the manufacturing process on large diameter wafers. Silica provides good process control, uniformity of refractive indexes, repeatability of parameters and low sensitivity to temperature. The design of grating on the waveguides is critical to achieve ultra-narrow linewidth on external cavity laser design. Bragg grating fabrication can be achieved with direct etching in Ge-doped silica waveguides, according to RIO’s proprietary processes.
Hybrid Integration Technology
RIO’s PLANEX™ laser cavity consists of the combination of two sub-components:
- Low noise InP or GaAs gain chip
- PLC (Planar Lightwave Circuit). Waveguide Bragg gratings on the PLC determines wavelength of external cavity laser.
- Mode size conversion enables an efficient coupling between gain chip and waveguides.
Along with PLC grating design, low noise gain chip design is another critical element to achieve ultra-narrow linewidth. Mode size conversion enables an efficient coupling between gain chip and waveguides. The hybrid integration of these sub-components results in a high performance that matches or exceeds the low noise and narrow linewidth performance of more complicated and higher cost lasers. The novelty of RIO’s approach includes:
- use of semiconductor process technology to build planar Bragg gratings on PLC rather than in fiber
- new hybrid integration technology to assemble optical components
- unique design technology to add significant performance advantages
- Scalability of the manufacturing processes to achieve significant cost reduction at large volume
RIO’s PLANEX technology has a path to integration in both parallel form (multiple wavelengths on the same chip) and functional form (additional component functionality) on the same platform. Parallel integration reduces the sequence of discrete manufacturing steps and parts, necessary to provide equivalent functionality.
High Reliability Packaging
RIO proprietary packaging technology enables very high reliability of lasers, suitable for the long term operation in the demanding conditions, including space and proven by various field applications in the harsh environments over more than a decade.