Weijing Kong

Nearly three orders of magnitude enhancement of Goos-Hanchen shift by exciting Bloch surface wave

Goos-Hanchen effect is experimentally studied when the Bloch surface wave is excited in the forbidden band of a one-dimensional photonic band-gap structure. By tuning the refractive index of the cladding covering the truncated photonic crystal structure, either a guided or a surface mode can be excited. In the latter case, strong enhancement of the Goos-Hanchen shift induced by the Bloch-surface-wave results in sub-millimeter shifts of the reflected beam position. Such giant Goos-Hanchen shift, ~750 times of the wavelength, could enable many intriguing applications that had been less than feasible to implement before.

Direct experimental observation of giant Goos–Hänchen shifts from bandgap-enhanced total internal reflection

Giant Goos-Hänchen (GH) shifts are experimentally demonstrated from a prism-coupled multilayer structure incorporating a one-dimensional photonic crystal (PC) through a bandgap-enhanced total internal reflection scheme. By combining the large phase changes near the bandgap of the PC and the low reflection loss of the total internal reflection, 2 orders of magnitude enhancement of the GH shift is realized with rather low extra optical loss, which might help to open the door toward many interesting applications for GH effects.

Fiber-to-Fiber Optical Switching Based on Gigantic Bloch-Surface-Wave-Induced Goos–Hanchen Shifts

Fiber-to-fiber on-off optical switching based on the gigantic Goos-Hanchen (GH) shift on an optical beam induced by the Bloch surface wave is experimentally demonstrated for the first time. Through changing the refractive index of the cladding covering a truncated 1-D photonic crystal, the enhanced GH shift can be toggled dynamically from zero to submillimeter range. By using the finite coupling aperture of the fiber and selecting an optimized pass region of the beam to the output fiber, high extinction ratio can be achieved with reasonable insertion loss. It is also demonstrated that a refractive index change of <; 2*10-3 is sufficient to realize the switching, which opens the way to realize faster and more compact integrated GH switches.

Highly Sensitive, Bloch Surface Wave D-Type Fiber Sensor

A novel sensor based on a D-type optical fiber coated with a specially designed dielectric multilayer forming a one-dimensional photonic bandgap structure is proposed. The characteristics of its propagation modes are numerically analyzed at a wavelength of 785 nm to evaluate the sensors performance. The results show that its sensitivity can drastically exceed that of its metal-coated, surface plasmon resonance counterpart, due to the sharp resonance and low wave-propagation loss of its Bloch surface wave. The novel sensor can also be easily adapted for all kinds of aqueous analytes of different refractive indices by modifying the photonic bandgap structure. This could lead to the development of compact, ultra-sensitive biochemical sensing devices.

Giant non-specular effects at the interface of Bloch surface wave structures

The interference of reflections and refractions in a periodical dielectric structure generates a surface electromagnetic wave named Bloch surface wave. The absence of ohmic losses renders the Bloch surface wave strongly enhance the non-specular effect, like the Goos-Hanchen shift, with low optical loss. In that case, giant non-specular effect induced by the Bloch-surface-wave is easy to observe. Here the spatial phase distribution is experimentally measured as well as the intensity distribution. Experiments reveal that the non-specular reflection could lead to strong spatial phase variation across the beam profile besides the intensity distortion. This discovery helps better understanding of the physical process of the non-specular reflection, and the observed giant non-specular effect provides potential applications involving high performance optical sensors.

Characteristic Optimization of Multilayer Dielectric for the Bloch-Surface-Wave Based Sensor

Through numerical simulations, some rules among the BSW characteristic information can be obtained. This paper points out that the narrowest reflectance dip, the maximum GH shift, the maximum penetration depth are obtained when the resonant angles close to the critical angle. And at that position the sensitivity is higher.

Boosting Goos-Hanchen shift from a Bloch surface wave structure by optimizing excitation angles

The Goos-Hanchen shift is studied via varying the theoretical model of photonic crystal structure. The giant GH shift is obtained when resonant angle near the critical angle, and enhanced about an order of magnitude.

Ultrasensitive Goos-Hanchen shift sensing using a photonic crystal structure

A novel Goos-Hanchen shift scheme solves the dilemma faced by similar schemes by offering both greatly enhanced Goos-Hanchen shifts and no optical loss, using a simple one-dimensional photonic crystal structure beyond the critical angle.

Giant Goos-Hanchen shift enhancement under total internal reflection by one-dimensional photonic crystals

Giant Goos-Hanchen shifts are experimentally demonstrated from a prism-coupled one-dimensional photonic crystal beyond the critical angle. Lossless reflection with such large GH shifts could enable many interesting applications.