Abstract:This paper discusses the influence of Sb/In ratio on the transport properties and crystal quality of the 200 nm InAs_xSb_1-x thin film. The Sb content of InAs_xSb_1-x thin film in all samples was verified by HRXRD of the symmetrical 004 reflections and asymmetrical 115 reflections. The calculation results show that the Sb component was 0.6 in the InAs_xSb_1-x thin film grown under the conditions of Sb/In ratio of 6 and As/In ratio of 3， which has the highest electron mobility （28 560 cm²/V·s） at 300 K. At the same time， the influence of V/III ratio on the transport properties and crystal quality of Al_0.2In_0.8Sb/InAs_xSb_1-x quantum well heterostructures also has been investigated. As a result， the Al_0.2In_0.8Sb/InAs_0.4Sb_0.6 quantum well heterostructure with a channel thickness of 30 nm grown under the conditions of Sb/In ratio of 6 and As/In ratio of 3 has a maximum electron mobility of 28 300 cm²/V·s and a minimum RMS roughness of 0.68 nm. Through optimizing the growth conditions， our samples have higher electron mobility and smoother surface morphology.

Abstract:Colloidal quantum dots （CQDs） are affected by the quantum confinement effect， which makes their bandgap tunable. This characteristic allows these materials to cover a broader infrared spectrum， providing a cost-effective alternative to traditional infrared detector technology. Recently， thanks to the solution processing properties of quantum dots and their ability to integrate with silicon-based readout circuits on a single chip， infrared detectors based on HgTe CQDs have shown great application prospects. However， facing the challenges of vertically stacked photovoltaic devices， such as barrier layer matching and film non-uniformity， most devices integrated with readout circuits still use a planar structure， which limits the efficiency of light absorption and the effective separation and collection of photo-generated carriers. Here， by synthesizing high-quality HgTe CQDs and precisely controlling the interface quality， we have successfully fabricated a photovoltaic detector based on HgTe and ZnO QDs. At a working temperature of 80 K， this detector achieved a low dark current of 5.23×10^-9 A cm^-2， a high rectification ratio， and satisfactory detection sensitivity. This work paves a new way for the vertical integration of HgTe CQDs on silicon-based readout circuits， demonstrating their great potential in the field of high-performance infrared detection.

Abstract:In this work， we investigate the impact of the whole small recess offset on DC and RF characteristics of InP high electron mobility transistors （HEMTs）. L_g = 80 nm HEMTs are fabricated with a double-recessed gate process. We focus on their DC and RF responses， including the maximum transconductance （g_{m_max}）， ON-resistance （R_ON）， current-gain cutoff frequency （f_T）， and maximum oscillation frequency （f_max）. The devices have almost same R_ON. The g_{m_max} improves as the whole small recess moves toward the source. However， a small gate to source capacitance （C_gs） and a small drain output conductance （g_ds） lead to the largest f_T， although the whole small gate recess moves toward the drain leads to the smaller g_{m_max}. According to the small-signal modeling， the device with the whole small recess toward drain exhibits an excellent RF characteristics， such as f_T = 372 GHz and f_max = 394 GHz. This result is achieved by paying attention to adjust resistive and capacitive parasitics， which play a key role in high-frequency response.

Abstract:Organic semiconductor materials have shown unique advantages in the development of optoelectronic devices due to their ease of preparation， low cost， lightweight， and flexibility. In this work， we explored the application of the organic semiconductor Y6-1O single crystal in photodetection devices. Firstly， Y6-1O single crystal material was prepared on a silicon substrate using solution droplet casting method. The optical properties of Y6-1O material were characterized by polarized optical microscopy， fluorescence spectroscopy， etc.， confirming its highly single crystalline performance and emission properties in the near-infrared region. Phototransistors based on Y6-1O materials with different thicknesses were then fabricated and tested. It was found that the devices exhibited good visible to near-infrared photoresponse， with the maximum photoresponse in the near-infrared region at 785 nm. The photocurrent on/off ratio reaches 10²， and photoresponsivity reaches 16 mA/W. It was also found that the spectral response of the device could be regulated by gate voltage as well as the material thickness， providing important conditions for optimizing the performance of near-infrared photodetectors. This study not only demonstrates the excellent performance of organic phototransistors based on Y6-1O single crystal material in near-infrared detection but also provides new ideas and directions for the future development of infrared detectors.

Abstract:Dual-band thermal emitters with narrow bandwidths are important in various applications in the infrared field， such as in infrared sensing and infrared imaging. However， conditions for narrowband emission in different wavelengths can conflict with each other， making it difficult to achieve dual-band emitter. In this paper， a new type of lithography-free infrared dual-band thermal emitter is proposed， which consists of alternately deposited Ge and YbF₃ films on Al films. The narrowband emission characteristics stem from the Tamm plasmon polaritons （TPP） that can be excited by the distributed Bragg reflector and the Al substrate under certain conditions. The geometric parameters are optimized using multi-objective particle swarm optimization. The experiment results confirm that dual-band emitter can simultaneously exhibit narrowband emitter characteristics in both mid-wave infrared （MWIR） and long-wave infrared （LWIR） regions. The proposed method can be used in the design of multi-band emitssion modulation applications， which can be applied in the fields of multi-gas sensing and multi-band infrared camouflage.

Abstract:With the development of remote sensing technology， the detection sensitivity of infrared system is increasingly required. The infrared imaging detection technology based on linear avalanche device can effectively improve the detection sensitivity in high frame frequency applications. Based on the short-wave infrared linear avalanche detector assembly of 512×512， a small-aperture and lightweight infrared imaging system is designed and its performance is tested under low reverse bias. The test results show that the increase of SNR of the imaging system based on the linear avalanche infrared detector is basically linear with the multiplication factor M under short integration time， and the SNR of the system is 3 times that of the traditional camera of the same caliber.

Abstract:In the realm of optoelectronics， photodetectors play pivotal roles， with applications spanning from high-speed data communication to precise environmental sensing. Despite the advancements， conventional photodetectors grapple with challenges with response speed and dark current. In this study， we present a photodetector based on a lateral MoTe₂ p-n junction， defined by a semi-floating ferroelectric gate. The strong ferroelectric fields and the depletion region of the p-n junction in the device are notably compact， which diminish the carrier transit time， thereby enhancing the speed of the photoelectric response. The non-volatile MoTe₂ homojunction， under the influence of external gate voltage pulses， can alter the orientation of the intrinsic electric field within the junction. As a photovoltaic detector， it achieves an ultra-low dark current of 20 pA， and a fast photo response of 2 μs. The spectral response is extended to the shortwave infrared range at 1550 nm. Furthermore， a logic computing system with light/no light as binary input is designed to convert the current signal to the voltage output. This research not only underscores the versatility of 2D materials in the realm of sophisticated photodetector design but also heralds new avenues for their application in energy-efficient， high-performance optoelectronic devices.

Abstract:Due to its distinctive traits such as low energy consumption， high transmittance， potent anti-interference capacity， fingerprint， THz flexible regulation assumes a crucial role in detection， imaging， radar， and military defense， and has garnered significant attention from scholars both domestically and internationally in recent years. Nevertheless， high costs and losses remain significant factors restricting the advancement of terahertz regulation. Perovskite materials possess outstanding photoelectric properties， a straightforward preparation process， the capacity for mass production， and thereby become one of the most promising materials for the fabrication of terahertz detectors. Additionally， the facile tunability of perovskite compensates for the difficulty in adjusting the metasurface and meets the requirement for tunable metasurface. The combination of the two enables effective regulation of terahertz in the light field. In this paper， we have designed two types of coded metasurface composed of organic-inorganic hybrid perovskite CH₃NH₃PbI₃， polyimide， and aluminum， and manipulated the operating frequencies of the two structures through light field control. The results were compared with theoretical calculations to verify the effect. The first structure can be controlled by the light field to select between a broadband operating frequency and high efficiency. The second structure functions only at 0.1THz and can vary the phase through light， thereby reversing the phase of the original structure to control the direction of beam reflection. On this basis， we fabricated the device and verified it. To a certain extent， this paper fills the void in the field of optical field regulation of coded metasurface and offers a train of thought for subsequent research.

Abstract:The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction. In satellite laser communication systems， the use of short-wave infrared wavelengths as beacon light can reduce atmospheric absorption and signal attenuation. However， there are strong non-uniformity and blind pixels in the short-wave infrared image， which makes the image distorted and leads to the decrease of spot centroid positioning accuracy. Therefore， the high-precision localization of the spot centroid of the short-wave infrared images is of great research significance. A high-precision spot centroid positioning model for short-wave infrared is proposed to correct for non-uniformity and blind pixels in short-wave infrared images and quantify the localization errors caused by the two， further model-based localization error simulations are performed， and a novel spot centroid positioning payload for satellite laser communications has been designed using the latest 640×512 planar array InGaAs shortwave infrared detector. The experimental results show that the non-uniformity of the corrected image is reduced from 7% to 0.6%， the blind pixels rejection rate reaches 100%， the frame rate can be up to 2000 Hz， and the spot centroid localization accuracy is as high as 0.1 pixel point， which realizes high-precision spot centroid localization of high-frame-frequency short-wave infrared images.

Abstract:In sub nanometer carbon nanotubes， water exhibits unique dynamic characteristics， and in the high-frequency region of the infrared spectrum， where the stretching vibrations of the internal oxygen-hydrogen （O-H） bonds are closely related to the hydrogen bonds （H-bonds） network between water molecules. Therefore， it is crucial to analyze the relationship between these two aspects. In this paper， the infrared spectrum and motion characteristics of the stretching vibrations of the O-H bonds in one-dimensional confined water （1DCW） and bulk water （BW） in （6， 6） single-walled carbon nanotubes （SWNT） are studied by molecular dynamics simulations. The results show that the stretching vibrations of the two O-H bonds in 1DCW exhibit different frequencies in the infrared spectrum， while the O-H bonds in BW display two identical main frequency peaks. Further analysis using the spring oscillator model reveals that the difference in the stretching amplitude of the O-H bonds is the main factor causing the change in vibration frequency， where an increase in stretching amplitude leads to a decrease in spring stiffness and， consequently， a lower vibration frequency. A more in-depth study found that the interaction of H-bonds between water molecules is the fundamental cause of the increased stretching amplitude and decreased vibration frequency of the O-H bonds. Finally， by analyzing the motion trajectory of the H atoms， the dynamic differences between 1DCW and BW are clearly revealed. These findings provide a new perspective for understanding the behavior of water molecules at the nanoscale and are of significant importance in advancing the development of infrared spectroscopy detection technology.

Abstract:The effects of calcium fluoride （CaF₂） doping on the optical and physical and chemical properties of Ytterbium fluoride （YbF₃） materials were studied. Pure YbF₃ thin films and YbF₃ thin films doped with different proportions of CaF₂ were deposited by electron beam and thermal evaporation， respectively. The characteristics of single layer were measured by spectrometer， stress measurement system， X-ray Diffraction （XRD）， Atomic Force Microscope （AFM） and other measuring devices. The optical constants were fitted by the classical Lorentz oscillator model. The results show that the single-layer film with better optical and physical and chemical properties is obtained by electron beam deposition， in the condition of 1% CaF₂ doping. A long-wave infrared anti-reflection multi-layer sample was designed and fabricated and its spectrum and reliability test were carried out. The results show that its transmittance in the long-wave infrared region is as high as 99%， and the reliability meets the requirements of space application.

Abstract:The near-infrared femtosecond laser induced ferroelectric domain inversion in an important method in 3D nonlinear photonic crystal fabrication. Using structures produced by this technique， a series of attractive results have been achieved in optical frequency conversion and nonlinear wavefront shaping. At present， the reported laser induced domain inversion were all implemented at room temperature. For ferroelectric crystals， it would reach the Curie point during heating， and many characterizations such as coercive field which relate to domain inversion may change seriously. However， the effect of crystal temperature on femtosecond laser induced domain inversion is undefined. In this work， the strontium barium niobate （Sr_xBa_1-xNbO₃） ferroelectric crystal with the Curie point of about 70-80 ℃ depends on component proportion of Sr and Ba was used for domain inversion. Direct near-infrared femtosecond laser writing was implemented at the temperature of 25-65 ℃. The domain inversion condition was judged based on the second-harmonic pattern in the far field. The variation tendency of threshold laser power for domain inversion depends on temperature was tested and possible reason was predicted.

Abstract:In response to the scarcity of infrared aircraft samples and the tendency of traditional deep learning to overfit， a few-shot infrared aircraft classification method based on cross-correlation networks is proposed. This method combines two core modules： a simple parameter-free self-attention and cross-attention. By analyzing the self-correlation and cross-correlation between support images and query images， it achieves effective classification of infrared aircraft under few-shot conditions. The proposed cross-correlation network integrates these two modules and is trained in an end-to-end manner. The simple parameter-free self-attention is responsible for extracting the internal structure of the image while the cross-attention can calculate the cross-correlation between images further extracting and fusing the features between images. Compared with existing few-shot infrared target classification models， this model focuses on the geometric structure and thermal texture information of infrared images by modeling the semantic relevance between the features of the support set and query set， thus better attending to the target objects. Experimental results show that this method outperforms existing infrared aircraft classification methods in various classification tasks， with the highest classification accuracy improvement exceeding 3%. In addition， ablation experiments and comparative experiments also prove the effectiveness of the method.

Abstract:This paper presents an innovative three-dimensional （3D） heterogeneously integrated photoreceiver， which is optimized for analog microwave optical links that demand both wide bandwidth and high input optical power. The key of this design is the uni-traveling-carrier photodiode （UTC-PD）， which has been flip-chip integrated onto a microwave integrated circuit submount. This integration approach enhances the photoreceiver''s bandwidth and high power handling capabilities. The material doping and epitaxial processes of the UTC photodiode were optimized to augment its power endurance. Meanwhile， the responsivity of the photodiode was improved through the adoption of an integrated back-illuminated lens complemented by the addition of a metallic reflective layer. By establishing a precise model of the photodiode， we have refined the bandwidth characteristic of the photoreceiver using impedance compensation and broadband matching circuit design techniques. Flip-chip bonding the photodiode chip onto the microwave integrated circuit chip has substantially mitigated the impact of interconnect circuits on high-frequency performance. Furthermore， the thermal conductivity and high-power resilience of the detector chip were enhanced via gold-tin alloy micro-bump interconnections and the design of a high thermal conductivity substrate layer. The three-dimensional heterogeneous integrated photoreceiver features a 1-dB bandwidth of 42 GHz， an RF return loss exceeding 11 dB， a responsivity surpassing 0.85 A/W， a dark current below 50 nA， and a saturated input optical power of over 120 mW.By leveraging the distinctive properties of the UTC-PD， our three-dimensional （3D） heterogeneous integrated photoreceiver design achieves superior efficiency and responsiveness， positioning it as a leading solution for cutting-edge microwave photonics applications.

Abstract:The three-dimensional perception of road objects in challenging environments is crucial for the development of autonomous vehicles that operating in all conditions， at all hours. Infrared binocular vision mimics the human binocular system， facilitating stereoscopic perception of objects in challenging conditions such as dim or zero-light environments. The core technology for stereoscopic perception in binocular vision systems is accurate object detection and matching. To streamline the complex sequence of object detection and matching procedures， a synchronous object detection and matching network （SODMNet） is proposed， which can perform synchronous detection and matching of infrared objects. SODMNet innovatively combines an object detection network with an object matching module， leveraging the deep features from the classification and regression branches as inputs for the object matching module. By concatenating these features with relative position encoding from the feature maps and processing the concatenated features through a convolutional network， the network generates feature descriptors for the left and right images. Object matching is then achieved by calculating the Euclidean distances between these descriptors， thus facilitating synchronous object detection and matching in binocular vision. In addition， a novel nighttime infrared binocular dataset， annotated with targets such as pedestrians and vehicles， is created to support the development and evaluation of the proposed network. Experimental results indicate that SODMNet achieves a significant improvement of more than 84.9% in object detection mean average precision （mAP） on this dataset， with an object matching average precision （AP） of 0.5777. These results demonstrate that SODMNet is capable of high-precision， synchronized object detection and matching in infrared binocular vision， marking a significant advancement in the field.

Abstract:In this paper， we propose an RLC equivalent circuit model theory which can accurately predict the spectral response and resonance characteristics of metamaterial absorption structures， extend its design， and characterize the parameters of the model in detail. By employing this model， we conducted computations to characterize the response wavelength and bandwidth of variously sized metamaterial absorbers. A comparative analysis with Finite Difference Time Domain （FDTD） simulations demonstrated a remarkable level of consistency in the results. The designed absorbers were fabricated using micro-nano fabrication processes， and were experimentally tested to demonstrate absorption rates exceeding 90% at a wavelength of 9.28 μm. The predicted results are then compared with test results. The comparison reveals good consistency in two aspects of the resonance responses， thereby confirming the rationality and accuracy of this model.