However, whereas an EDFA is made using a free-standing fiber, an EDWA is typically produced on a planar substrate, sometimes in ways that are very similar to the methods used in electronic integrated circuit manufacturing.
MOEC developed a unique micro-mechanical approach to producing channel waveguides that can be doped with rare-earth elements at high concentrations.
The primary way to couple light in and out of such a waveguide was by using bulk optical components, such as prisms, mirrors and lenses, which further complicated their use in fiber-optic systems.
[4] However, due to a relatively low refractive index contrast between the core and the cladding in these waveguides, the selection of optical elements that can be produced on such a platform was rather limited and the resulting circuit size tended to be large, i.e. comparable to then available fiber-optic counterparts.
[5] They experimented with different glass compositions, including aluminosilicate, phosphate, soda-lime and others, which could be deposited as thin layers on top of silicon substrates.
Those lead to relatively higher noise figures and lower saturation powers, although the differences can be very small, sometimes amounting a fraction of dB (decibel).
The EDWA technology allows one to potentially produce a whole system using a single integrated optical circuit, as in a system-on-a-chip,[14] rather than an assembly of individual fiber-optic components.
In such systems, EDWA may then hold an advantage over EDFA-based solutions, due to the smaller size and potentially lower cost.