Performance evaluation of WDM components based on tunable dielectric membrane technology

Wavelength division multiplexing has become a leading technology for long-haul transmission systems which operate at 1550 nm wavelength. The recent slump in the fibre optics industry has put a strong focus on the development of new flexible and tunable components, as well as cost effectiveness and reliability. Two-chip micromachined devices are very promising candidates to fulfil these demands. A tunable optical filter structure is discussed, which uses a simple bulk-micromachining process based on low-cost dielectric Bragg mirrors. The tuning is achieved by current-induced thermal heating of the membrane suspensions. This concept combines the advantages of low-cost dielectric mirror processing and the simple actuation principle by current flow to create a best-of-breed two-chip solution. The alignment process of the two-chip cavity has been simplified to the point where a simple place-and-fix strategy can be applied. Based on this concept, a tunable two-chip resonant-cavity light-emitting diode (RC-LED) is presented, which utilises the same bulk-micromachined chip. This validates that these micromachined tunable membranes can serve as basic building blocks for a wide variety of tunable components for wavelength division multiplexing systems, such as optical filters, receivers and vertical-cavity surface-emitting lasers (VCSELs).