Table 3.
Examples for microcavities that have been utilized or proposed for utilization in biosensing applications.
| Optical resonator | Device example | Q in air/in water | Diameter | Fabrication |
|---|---|---|---|---|
| Microsphere waveguide coupled [13, 32, 38, 75, 87, 102, 117, 118] |
|
8×109/107–108 | 50–500 μm | Usually formed by melting a fiber tip |
| Microsphere, prism coupled [48, 119] (reprinted with permission from [48], copyright (2008), American Institute of Physics) |
|
/9×105 | 30~40 μm | Arrayed from a batch of polystyrene microspheres in solution |
| Microsphere, angle polished fiber coupled [120, 121] (reproduced with permission, © (1999) Optical Society of America) |
|
1×108 | ~500 μm | Microspheres fabricated by fusing high-purity silica preforms in a hydrogen-oxygen flame |
| Microtoroid, fiber coupled [16, 66, 67, 70] |
|
8×108/107–108 | 30~200 μm | CO2 reflow of an under-cut silica micro-disk on silicon wafer |
| Ring resonator, waveguide coupled [24, 52, 53, 111, 122–125] (image reproduced with permission from the publisher, [24]) |
|
/4×104–2×105 | ~20–200 μm | Ring resonator sensor arrays fabricated by lithography technology |
| Fluorescent microsphere [93, 101, 126–129] (image reproduced with permission from the publisher, [127]) |
|
/5000 | ~8–15 μm | Microspheres doped with optical gain medium, such as dye |
| Capillary, fiber coupled (LCORR) [42, 56] (reproduced with permission, ©(2006) Optical Society of America) |
|
/105–107 | ~150 μm | Softening (CO2 laser) and stretching a fused silica capillary |
| Disk resonator [130, 131], waveguide coupled (reprinted from [131], copyright (2010), with permission from Elsevier) |
|
~104 | 10 μm–100 μm | Fabricated from silicon oxy-nitride film on a silicon wafer by lithography technology |
| Bottleneck resonator [132] |
|
~108 | 30–40 μm | Fabricated from standard optical glass using a two-step heat-and-pull process |
| Microtube ring resonators [133, 134] (reprinted with permission from [133], copyright (2011) American Chemical Society) |
|
/100~300 | <10 μm | Roll up of a strained SiO/nanomembrane to SiO2 form a micro-tube with thin wall |
| Photonic crystal resonator [115, 116, 106, 135–137] (reproduced with permission, © (2007) Optical Society of America) |
|
106 | Micron-scale | e-beam lithography and reactive ion etching |
| Fabry perot resonator [138] |
|
Finesse: 38 | 40 μm | Resonator is formed between two highly reflecting reflectors composed of Bragg two period Si/SiO2 structures |
| Fiber-based [139, 140] (reprinted with permission from [139], copyright (2005), American Institute of Physics) |
|
104~106 | 20~200 μm | Resonator is formed beween the plane tip of a fiber and a concave micro-mirror fabricated by standard silicon etching and optical coating techniques |
| Microbubble [141–143] (reproduced with permission, © (2011) Optical Society of America) |
|
103~107 | 70~500 μm | Heating a glass capillary with a CO2 laser |
| Micro-coil [144–146] |
|
106 | 500 μm | Wind a microfiber coil on a cylindrical rod with lower refractive index |
| Photonic-plasmonic WGM: microsphere coupled to nanoantenna [58, 147–149] (reprinted with permission from [147], copyright (2011), American Institute of Physics) |
|
/106 | Light localized at the nanoantenna site | Nanoparticle layer deposition, nanoparticle WGM trapping |