Infrared optoelectronic and information acquisition sensing technology development


Junhao Chu

In 21st century, human being goes into the information age. The information acquisition technology which uses the optic as the information carrier, and multi-species information sensing technology mainly based on optical information sensing , have become one of the frontiers of the information and science technology. Nowadays, people not only have a deeper acknowledgement of optic, thermal, electric, magnetic and micro-force, also people have continuously strengthened capability of optoelectronic material and preparation, representation and property control of its micro-structure. This background promotes the information acquisition and sensing technology development, and drives the human being ¡°sense¡± extend and expand continuously.

1. Development trend

Information acquisition and sensing technology depends on the conversion achievement of the substance movement state in optoelectronic functional material and its device structure. The process and its law of optical-to electronically, electronically-to optical and optical-to optical conversion, and specifically device structure design and preparation technology are the scientific fundamental of information acquisition and sensing technology. Currently the information acquisition and sensing technology mainly have three important development trends.

1.1 Infrared optoelectronic physics research

The main driven force of infrared optoelectronic physics development is the requirement of important applications and subject development. Seen from the subject development, currently the infrared optoelectronic physics requires deeply research on infrared radiation of excitation, transmission and receiving physical process in substance, especially requires further research on infrared-to electronically conversion process, electronically-to infrared conversion process, infrared-to infrared infrared-to visible light mutual conversion and its micro-mechanics. Seen from the application requirements, the most important is the research of large scale infrared focal plane array (FPA) in different wave bands, mid-infrared and far-infrared wave bands laser, infrared mono-photon detector, THz optical source and detector, and so on. All of these have important applications in remote sensing technology, national defense and military affairs, resource and environment, quantum information, industry and agriculture, medical communication, scientific instrument and so on. The contemporary infrared optoelectronic physics research theme is composed of infrared functional material and its micro-structure preparation and property control, the law research of infrared-to optoelectronic excited conversion and optical-to optical conversion, various infrared devices physics and preparation, and the research of intercross of infrared physics with other subjects and so on.

1.2 Infrared optoelectronic material and FPA device information acquisition technology

Infrared optoelectronic material is the foundation of device. At present large scale infrared FPA is the most advanced 3rd generation infrared detector, which acquires information through the photo produced carrier that has been excited by infrared in optoelectronic functional material 2-D sensitive element array, then by signal processing, finally obtain the infrared image and spectrum of target object directly by staring way. Currently the infrared FPA based on narrow forbidden band gap semiconductor TeCdHg thin film material is the prevalent development trend. Meanwhile, III-V semiconductor quantum well structure has its advantage in multicolor infrared detector, which is the focus we have concerned. The above devices have to operate at the liquid nitrogen temperature (77K), therefore, on one hand explores the possibility of improving the operating temperature of photon-type infrared detector, on the other hand, develops the room temperature operating infrared devices, which are the important research direction, at present uncooled infrared focal plane technology like ferroelectric thin film is the focus that has been concerned a lot internationally. These three aspects research involves infrared functional material growth, optical-electrical excited dynamics research, FPA device physical model, FPA key technology foundation, and so on.

1.3 Multi-sensing, multi-spectrum as well as its fusion and integrating sensing technology

Based on the development of various information and multi-spectrum sensing technology, develop the multi-sensing and multi-spectrum information fusion technology, including wide area (land, ocean, air, space) wireless sensing system, which is the hotspot of the information acquisition and processing. It requires developing various sensors, including infrared, ultraviolet, pressure, vibration, sound, electromagnetic, chemistry, biology, mono-photon sensors, simultaneously, developing multi-spectrum range sensing technology, and research multi-spectrum information fusion algorithm, in order to obtain various target parameters information from the aspect of multi-sensing and multi-spectrum.

1.4 Advanced infrared detecting and sensing technology and subject intercross

The infrared optoelectronic physics is an intercrossed subject of optics and condensed state physics. Meanwhile it provides important research theme by intercrossing with other subjects. Advanced infrared detecting and sensing technology could obtain infrared spectrum and other characteristic spectrum and its image of target object, this information can be used to recognize, quantitatively analyze and monitor. It could be applied in both macro-object, such as ground, water area, weather and micro-object, such as cell, single atom or molecule; also both in immobile object and mobile object. Infrared optoelectronics intercrosses with life sciences, environment sciences and geosciences is an important research theme. People expect to judge biological and chemical process and other plentiful substance processes through spectrum of life or organic substance. People could apply infrared technology to recognize, monitor and control various condensed state substances. It requires to research the characteristic spectrum of condensed state substance in advance, research fixed coordinate curve, then apply to supervise reorganization or real-time monitor. These condensed state substance involves mineral resource, contamination, various crops, environmental object, life substance and other complicated substance system; spectrum characteristics involves reflection, transmission, absorption and radiation characteristics, and fluorescent, Raman, magneto-optic ,polarization and other characteristics. This aspect research is the important foundation of developing various special infrared monitoring system, also is the important approach of infrared optoelectronic physics fundamental research related to high-techoperational application and industrialization, which provides an extensive foreground.

In international, many countries have placed the information acquisition and sensing technology as the key research field. Concerning the FPA information acquisition and advanced sensing technology has become the theme of nearly ten international conferences.

2. Several important development directions

This field should emphasis under mentioned important development directions.

2.1 On the FPA information acquisition and its application aspect, mainly developing the high-performance large scale FPA, increasing the operating temperature of FPA, exploring new type FPA technology, also achieving multi-aspects applications.

At present it¡¯s primarily develops the high sensitivity large scale infrared FPA based on TeCdHg optic sensitive element, and applies in the aerospace remote sensing technology. Infrared focal plane subassembly is one of the key components of advanced space remote sensing apparatus. Prewarning, scout and other technologies development has an urgent requirement of engineering application of above 6000 elements long line array and above 256¡Á256 elements large scale infrared focal plane subassembly. Meanwhile the multi-spectrum channel technology will has a significant meaning.

The important development direction of FPA is to increase the operating temperature. At present the TeCdHg infrared focal plane detector operates at low temperature of 77K. Therefore on one hand we should increase the operating temperature of TeCdHg device reaching the thermoelectric coolingtemperature range, on the other handintegrating the uncooled infrared focal plane chip in single chip of silicon reading circuit is an importantendeavor direction. Developing the uncooled infrared focal plane can achieve infrared detect imaging of near-infrared, mid-infrared and far-infrared wave bands in room temperature, which is extremely significant. Besides, in order to use the FPA conveniently, infrared imaging sensor of flexible material also is the key research. Developing the uncooled infrared focal plane detectoron the flexible material, achieving including infrared imaging on the bendable focal plane. In the short wave band of electromagnetic wave , ultraviolet , X-ray and ¦Ã-ray, FPA information acquisition technology will has extensive applications in space, body checking , safety monitoring and other aspects.

At present infrared FPA reads out the infrared converted electric signal through silicon reading circuit, of which structure is complicated. Therefore, developing the observation mirror of infrared-to visible light direct conversion is another important development trend of infrared FPA. Expecting people can achieve observe target in short wave, middle wave and long wave infrared wave bands by putting on a tailor-made glasses like owl night sighting.

2.2 On the multi-sensing, multi-spectrum, integrating, minimizing and its information fusion technology aspects, mainly developing the various information sensing technology, multi-wavebands and multi-spectrum sensing device, as well as single cell, single molecule, single atom, single photon information sensing technology.

Developing multi-types information sensing, multi-spectrum information sensing as well as their fusion technology are the present hotspot of information acquisition and processing. At present, it requires to develop various sensors, including infrared, ultraviolet, X-radiation, ¦Ã-radiation, pressure, vibration, sound, electromagnetic, chemistry, biology, mono-photon and some other sensors, simultaneously, develop multi-spectrum information sensing technology. Multi-sensing, multi-spectrum information fusion technology collects information of various sensors, processes synthetically, and from the multi-spectrum aspect obtains various target parameter information, these information including land, ocean, air and space 4-D wide area wireless sensing system. Multi-sensing and multi-spectrum information acquisition and sensing as well as the information fusion technology will be applied practically. On the multi-spectrum information fusion technology aspect, for few years in the further the solid state infrared/visible light/ultraviolet focal plane imaging sensor will be applied on multi-wave band and multi-spectrum radiation measurement, and research the earth surface vegetation, environment, atmosphere and geology from the air. Simultaneously, it can recognize several complicated targets on the air. It has an urgent requirement of environment monitoring, satellite communication, missile flame detecting and some other military and civil fields.

Multi-type information sensing that mainly based on the electromagnetic wave is one of the important developing directions of advanced sensing technology. The radar wave band is the important wave band of information acquisition and sensing technology. High resolution satellite-carried synthesize aperture radar is expected to be applied practically in the future. Large aperture centimeter and millimeter wavelength staring imaging technology will be developed.

Micro-pressure sensing technology is an important direction. The touch sensor will be applied practically in the long-distance operation system. The haptical information of human being could be long-distance transferred and interacted through (wireless) network, which can be applied in the fields of aerospace, stimulated training, long-distance medical cure and tend, battlefield and antiterrorist danger obviation. By introducing the high resolving powered resonant sensor mechanics and nano-electro-mechanical system (NEMS) technology to develop the sensors that are sensitive to microcosmic mass, force or angular momentum, people can obtain the mass or force information at single cell, single molecule or single atom levels. Integrated micro-device sensor will be applied. By adopting the Micro-electromechanical Systems (MEMS) minimized integration technology, scientific instrument system which has sensitive detecting function like spectral gas analyzer could be cranked out at a device size level and sensor type, which can be carried to many occasions to do the detecting. Furthermore, the synthetically judgment technology through large quantity sensitive devices integrated array has been developed successfully.

2.3 On the aspect of advanced information acquisition and sensing technology application, mainly developing the acquisition technology on high resolution image, thermal image, spectrum image and characteristic image as well as the target object recognition technology, especially paying more attention on the space application and body healthy environment monitor application.

Satellite-carried high resolution infrared camera has a significant meaning of the information acquisition. Based on the development of multi-element and multi-color infrared detector integrated subassembly, it could achieve high resolution infrared camera to meet the requirement of the battlefield environmental air-to-ground high resolution detecting. The high resolution infrared camera adopts 15 channels of photovoltaic array and 2 channels of photoconductive array internationally, and the elements number has reached 94 to 192 unequally. The development trend is to increase the amount of the detector elements and spectrum channels and also improve the performance and the reliability.

The information acquisition technology related to the body health will be developed rapidly. Non-wounded blood sugar testing of diabetic, the physical analysis of the information in herbalism that obtained from ¡°inspection and observation, auscultation and olfaction, pulse-feeling and palpation¡± and acupuncture, and the laws of the frequency spectrum and the body interaction will be explored gradually. Based on these laws people will establish corresponding detecting instrument, not only in hospital, but also in your home, so that it will applied practically that people could detect themselves on the related body health items without any wounded. Real effective physical therapy instrument will also be practically applied.

Researching on chip subassembly of intelligent infrared system has significant meaning. Intelligent infrared system chip not only can obtain infrared object image, but also can obtain spectrum distribution of points on the object, also confirm the component and characteristic of object through spectrum characteristic, and achieve this function in the combined chip subassembly. For the hardware based on the infrared focal plane imaging spectrum, for the software based on the infrared characteristic spectrum of previous obtained target object, making a qualitative or quantitative judgment of pending measurement target object through measuring the imaging spectrum of pending measurement target object and making comparison. Miniature whole analysis system chip could integrate the sample processing, biochemicalreaction and detecting system into chip, achieving the whole system integrated and minimized, mostly applied in medical diagnose, environment monitoring and food safety detecting.

Polarized remote sensing and detecting technology has research development hopefully in the future. The remote sensing and detecting technology including polarized information will greatly increase the information capability of target object, which could be used to recognize and judge target object. Meanwhile the technology of detecting the atmosphere temperature, humidity and pressure at the same time from space, which could provide the date of global 3-D weather elements and minimal components in atmosphere for value weather forecast and atmosphere environment monitoring.

3. Development suggestion

Surrounding the abovementioned three aspects of development trends and several important development directions, China should organize resource designedly, and carry on the key point research. While developing the information acquisition and sensing technology, we must strengthen thefundamental research at the same time. Above all, the information acquisition and sensing technology depends on the conversion achievement of the substance movement state in optoelectronic functional materialand its device structure. The research of the process and its law of optical-to electronically, electronically-to optical and optical-to optical conversion, as well as the research of designed specific device structure and its preparation technology , which aims at achieving the information acquisition and sensing , these are the scientific foundation and innovative source of information acquisition and sensing technology. Based on the strong of the fundamental research, we should encourage raising and actualizing the new concept and new design of information acquisition and sensing technology. The extension and expansion of human being ¡°sense¡± is an infinite create process.

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