Rajic S, Corbeil J L, Datskos P G
Oak Ridge National Laboratory, P.O. Box 2008, MS-6141, Oak Ridge, TN 37831-6141, USA.
Ultramicroscopy. 2003 Oct-Nov;97(1-4):473-9. doi: 10.1016/S0304-3991(03)00076-7.
Periodic photonic crystal structures channel electromagnetic waves much as semiconductors/quantum wells channel electrons. Photonic bandgap crystals (PBC) are fabricated by arranging sub-wavelength alternating materials with high and low dielectric constants to produce a desired effective bandgap. Photons with energy within this bandgap cannot propagate through the structure. This property has made these structures useful for microwave applications such as frequency-selective surfaces, narrowband filters, and antenna substrates when the dimensions are on the order of millimeters. They are also potentially very useful, albeit much more difficult to fabricate, in the visible/near-infrared region for various applications when the smallest dimensions are at the edge of current micro-lithography fabrication tools. We micro-fabricated suspended free standing micro-structure bridge waveguides to serve as substrates for PBC features. These micro-bridges were fabricated onto commercial silicon-on-insulator wafers. Nanoscale periodic features were fabricated onto these micro-structure bridges to form a tunable system. When this combined structure is perturbed, such as mechanical deflection of the suspended composite structure at resonance, there can be a realtime shift in the material effective bandgap due to slight geometric alterations due to the induced mechanical stress. Extremely high resonance frequencies/device speeds are possible with these very small dimension MEMS.
周期性光子晶体结构对电磁波的传导作用，类似于半导体/量子阱对电子的传导作用。光子带隙晶体（PBC）是通过排列具有高介电常数和低介电常数的亚波长交替材料来制造的，以产生所需的有效带隙。能量在该带隙内的光子无法通过该结构传播。当尺寸在毫米量级时，这种特性使这些结构可用于诸如频率选择表面、窄带滤波器和天线基板等微波应用。当最小尺寸处于当前微光刻制造工具的边缘时，它们在可见光/近红外区域用于各种应用时也可能非常有用，尽管制造起来要困难得多。我们微制造了悬空的独立微结构桥形波导，用作具有PBC特性的基板。这些微桥被制造在商用绝缘体上硅晶圆上。在这些微结构桥上制造纳米级周期性特征，以形成一个可调谐系统。当这种组合结构受到扰动时，例如在共振时悬空复合结构的机械偏转，由于诱导机械应力导致的轻微几何变化，材料有效带隙可能会实时偏移。利用这些非常小尺寸的微机电系统（MEMS），可以实现极高的共振频率/器件速度。
