In this report, we present a new type of non-contact detection method for glucose molecule using nano antenna array based bio sensing chip that operates at terahertz frequency range (0.5 – 2.5 THz). Localized and hugely enhanced transmitted terahertz field by nano antenna array in the sensing chip induced enhancement of absorption coefficient of glucose molecule that enables us to detect even very small volume of molecules. Nano antenna based terahertz sensing chip can be expected to offer accurate identification of glucose level as a non-invasive and painless sensing tool with high sensitivity.
An efficient split-step time-domain modeling method is developed for the simulation of pulse propagation characteristics through all-pass and add/drop filters made of ring resonators. The bus and ring waveguides are divided into several sections of equal size and the phase and coupling is updated during each time step corresponding to the propagation time over a section. The pulse propagation dependence on the coupling ratio of the all-pass and add/drop filters is investigated. It is shown that very large scale ring resonator devices such as cascaded add/drop filters can be very efficiently modeled in time domain.
We investigate the properties of a multimode-interference (MMI) coupled micro ring cavity resonator with
total-internal-reflection (TIR) mirrors and a semiconductor optical amplifier (SOA). The TIR mirrors were fabricated
by the self-aligned process with a loss of 0.7 dB per mirror. The length and width of an MMI are 142 &mgr;m and 10 &mgr;m,
respectively. The resulting free spectral range (FSR) of the resonator was approximately 1.698 nm near 1571 nm and
the extinction ratio was about 17 dB. These devices might be useful as optical switching and add-drop filters in a
photonic integrated circuit or as small and fast resonator devices.
The butt-coupled (BT) sampled grating distributed Bragg reflector laser diode (SGDBR-LD) was designed and fabricated using planar buried heterostructure (PBH), enabling a low threshold current and a stable fundamental transverse mode. The but-coupled SGDBR-LD's with target tuning ranges of 44.4nm was fabricated, and the tuning ranges were experimentally measured to be 44.4nm. The measured peak periods of the fabricated SGDBR-LD's were well matched with theoretical values and output power is close to calculated values. The side mode suppression ratio of more than 35dB was obtained in the whole tuning range. The output power variation was less than 5dB, which is 4dB smaller than that of RWG structure.
Wavelength tuning and dynamic characteristics due to the vernier effect of a coupled-ring reflector (CRR) laser diode including active region within resonators are investigated using a split-step time-domain modelling approach. A CRR provides a strong mode-selection filter and could significantly extend the effective cavity length of a conventional Fabry-Perot laser. The simulation results for a particular design show that the tuning range as wide as 33 nm is possible with side mode suppression ratio exceeding 35dB. The modulation frequency could be 8 GHz and the frequency chirp could be in the range of 50 ~ 200 MHz/mA.