Tannersfriend: Could it be that for most of the functionallities of POET you just do not need this fourth terminal ?

Yes and no. The most recent MD&A explains that conventionally three terminals are enough for the desired functionality as such. However, if you want the thyristor to switch really fast, you need the forth one.

Well, they could have known that since 1977: "Use the forth, Luke!" :-)

Over the past several months we have encountered challenges in the design and manufacturing of the GaAs-based monolithic chip. The primary POET technology utilizes a Thyristor (Double Heterojunction Opto-Electronic Switch – DOES) as the fundamental switch element for the lasers and detectors. Conventional Thyristors are typically three terminal devices, but they lack the ability for fast switching. High speed switching requires access to all four terminals of the POET Thyristor, but electrical access to the fourth terminal has proved extremely challenging. As an alternative to the original thyristor-based switch, we began a program using a bipolar design and we have demonstrated proof of concept with this approach. However, the bipolar switch design is fabricated on a different epitaxial stack design than the thyristor, requiring either the completion of the development using a thyristor switch, or re-developing the detector, VCSEL and the HFETs on a new epitaxial stack. Because of the high cost and relatively long development cycles related to GaAs platform, we have determined that we should not proceed with the GaAs development program without a strategic partner and the funding such a partner would provide. Instead, we are focusing on the nearer-term, higher return on investment opportunities by addressing the much larger, high-growth markets afforded to us with the InP-based hybrid technology.