利用二氧化碳气体分子在4.25 μｍ处的基频吸收带，研制了一种差分式中红外二氧化碳检测系统.系统的光路部分由热辐射红外光源、双通道热释电探测器和球面反射镜构成，电路部分主要包括信号处理、光源驱动及主控模块.采用Tracepro软件对气室结构进行仿真和优化设计，使气体吸收光程达到30 cm，改善了系统的性能.实验研究了系统对不同浓度二氧化碳气体样品的传感特性.实验结果表明，由拟合曲线得到的浓度与实际浓度误差较小，在0~5 000 ppm范围内，测得二氧化碳浓度的标准差小于45 ppm，而在500 ppm以下，测量浓度的标准差小于5 ppm；对浓度为0 ppm的二氧化碳气体样品连续测量2h，测量结果的标准差约为2.8 ppm；根据Allan方差分析得到系统的1σ检测下限为2.5 ppm.在每个二氧化碳传感器上增加无线模块nRF24L01，构成传感器节点，在选定的日光温室大棚中构建了无线传感器网络，采集了温室大棚中的二氧化碳浓度信息，验证了所研制的传感器性能.

A mid-infrared carbon dioxide (CO₂) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease response time and suppress environmental influence, respectively. An optical module is developed using a cost-effective wideband mid-infrared light source, a dual-channel pyre electrical detector and a spherical mirror, and the moisture-proof function is specially designed for enabling the application of this sensor in greenhouse with high humidity. Experiments are carried out to evaluate the sensing performance on CO₂concentration. According to the experimental results, the limit of detection (LoD) is about 3×10^{-5with an absorption length of 30 cm. The relative detection error is less than 5% within the measurement range of 3×10-5—5×10-3. Based on 10 h long-term stability measurement on 5×10-4and 2×10-3standard CO2 samples, the maximum fluctuations are 1.08% and 3.6%, respectively. By using a 2.4 GHz wireless network communication system for remote monitoring and data recording, a field measurement of this sensor in a greenhouse is conducted, and good performance is proven in such circumstance.}

A portable dual-channel digital/analogue hybrid lock-in amplifier (LIA) is developed, and its amplitude detection error is less than 10% when the signal-to-noise ratio (SNR) is larger than -12 dB. Then, a differential mid-infrared methane (CH4) detection device is experimentally demonstrated based on a wideband incandescence wire-source and a multi-pass spherical reflector. The experiments are carried out to obtain the sensing performance of the device. With the absorption length of only ~4.8 cm, the limit of detection (LoD) is about 71.43 mg/m³, and the detection range is from 0 mg/m³ to 5.00×10⁴ mg/m³. As the concentration gets larger than 714.30 mg/m³, the relative detection error falls into the range of -5%—+5%. Two seven-hour-measurements are done on the CH₄ samples with concentrations of 1.43×10³ mg/m³and 4.29×10³ mg/m³, respectively, and the results show that the maximum relative error is less than 5%. Because of the cost effective incandescence wire-source, the small-size and inexpensive dual-channel LIA, and the small-size absorption pool and reflector, the developed device shows potential applications of CH₄ detection in coal mine production and environmental protection.

Eight-port optical routers are widely used in cluster-mesh photonic networks-on-chip (NoC). By using 24 groups of cross-coupling two-ring resonators, a 1-stage 8-port polymer optical router is proposed, which can optically route 7 channel wavelength data streams along definite path in two-dimensional (2D) plane. Under the selected 7 channel wavelengths, the insertion losses along all routing paths are within 0.02-0.58 dB, the maximum crosstalk of all routing operations is less than -39 dB, and the device footprint size is about 0.79 mm². Then, a universal novel structure and routing scheme of N-stage cascaded 8-port optical router are presented, which contains 7N channel wavelengths. Because of the good scalability in wavelength, this device shows potential application of wideband signal routing in optical NoC.