Photonic Crystal Multiplxing Dual-Parameter Sensor Array Based On Photonic Crystal Multimode Cavities

Owing to the great capability to manipulate light propagation,lab-on-a-chip optical devices utilizing photonic crystal(PC)are attractive in optical communication systems.Particularly,PC sensors seem to be very promising in lab-on-a-chip applications,because of their ultra-compact sizes,small footprints,low power consumptions and fitting in monolithic integration.Recently,PC sensors using one resonant mode have been widely applied in refractive index(RI)sensing,temperature sensing,pressure sensing and biochemical sensing.With the development of sensing research,dual-parameter sensing has drawn extensive attentions.In this paper,the concept of"multiplexing dual-parameter sensing" is introduced and studied.We combine the concept of"multiplexing" with dual-parameter sensing and design sensor structures whose each sensor unit is qualified for dual-parameter sensing.The achievements of this paper can be summarized as follows:Firstly,the temperature and RI dual-parameter sensing principle and feasibility condition of PC multimode cavity sensor are deduced.In detail,after obtaining the RI sensitivity of 0th-order and lst-order modes and the temperature sensitivity of 0th-order and lst-order modes,based on a sensing matrix and our observing resonant wavelengths of Oth-order and 1St-order modes,the change of RI and temperature can be calculated.Only one PC cavity is used in dual-parameter sensing and this method is essential for optical integrated circuit in the future.Secondly,a PC ellipical holes multimode nanobeam cavity dual-parameter sensor(PC-EDPS)is introduced.PC-EDPS is degined by tapering the lattice space of elliptical holes from the center to both ends quadratically,while other structural parameters remain.Based on the 0th-order and 1St-order modes,PC-EDPS can be used in dual-parameter sensing with a much smaller footprint of 12?mx0.7?mx0.22?m(width x length x height).Thirdlly,the concept of "multiplexing dual-parameter sensing" is introduced.A line-defect based PC multimode cavity(PC-MLC)is des:igned and two cascaded PC-MLCs,whose Q-factors are both over 29000 for 0th-order mode and over 7000 for the 1St-order mode,are coupled to a photonic crystal waveguide as two sensing units(Sensor Unit#1 and Sensor Unit#2),to form a photonic crystal multiplexing dual-parameter sensor array(MDPSA).Based on a sensing matrix,Sensor Unit#1 and Sensor Unit#2 can be used in simultaneous detection of RI and temperature at the same time.In addition,the total footprint of the proposed sensor array is ultra-compactness of 14.5?m×18.6?m × 0.22?m(width x length x height).Last but not least,an ultra-compact low crosstalk photonic crystal dual-channel sensor array(DCSA)for multiplexing dual-parameter sensing is proposed.Firstly,a PC elliptical holes multimode nanobeam cavity(EMNC)is designed.By applying three-dimensional finite-difference time-domain(3D-FDTD)simulations,high Q-factors above 1×106 of 0th-order mode and 1×105 of 1St-order mode can be simultaneously achieved.Next,an equal power splitter,a power combiner and two EMNCs are introduced to form a PhC dual-channel sensor(DCSA).Based on a sensing matrix,each channel of DCSA(EMNC-1 and EMNC-2)can be used in simultaneous detection of RI and temperature independently.Particularly,the total footprint is only about 26.5?m x6.2?m × 0.22?m(length x width x high),which is potentially a promising platform for complex optical multi-sensing network.