Performance parameter decoupled high efficiency micro ring laser cavity for biosensing

High quality (Q) factor micro resonators have shown many promising biosensing applications during recent years[1-5]. A higher Q means a narrower resonant peak, thus, in principle, a smaller resonant wavelength shift can be detected which corresponding to a lower detection limit. One way to dramatically increasing the Q of a micro cavity is to provide gain inside the cavity and transform it into a laser. Recently, a Yb³⁺ doped Al₂O₃ micro ring laser sensor has been demonstrated[6]. However, design and optimize the performance of an optically pumped micro ring laser sensor is very difficult with the typical ring structure. This is due to the fact that every physical parameter (such as waveguide width, thickness, ring radius, and gap size) is entangled with multiple performance parameters (such as sensitivity, free spectral range and laser threshold). We proposed a design methodology in our previous work[7] to overcome this difficulty by decoupling the performance parameters into several regions in the cavity as shown in Fig. 1. (a). In this work, we describe the fabricated device and shown its preliminary experimental results.