Micro-optical electromechanical systems in optical communications, digital image acquisition, display and processing, IT peripherals, environmental protection, automated biomedical equipment, industrial maintenance and so on has a very good prospect of application, foreign countries in the above areas to carry out a series of micro-optical electromechanical systems technology and product research and development. The switching element is the core component of the optical network, and its performance is the key to determine the performance of the network. MOEMS-based optical switch, due to its format, wavelength, protocol, modulation, polarization and transmission direction of the optical signal are independent of, and in the loss and scalability are better than other types, and the future development of optical networks required by the transparency and scalability and other trends in line with the development of optical networks, is becoming the mainstream in the core optical switching devices. The vast majority of recent innovations and advances in MOEMS are reflected in the field of optical communications, which has become one of the major application areas for MOEMS.
In recent years is vigorously developing an integrated MOEMS optical switch, that is, on a silicon wafer with micromachining technology to make a large number of movable miniature lenses composed of switch arrays. AT&T Laboratories used MOEMS technology to develop an 8 × 8 optical switch array. The size of this micro-mechanical optical switch is about 1 cm × 1 cm, each input port corresponds to a collimated microlens, each output port corresponds to a focusing microlens, the main components of the optical switch is a matrix of 8 rows and 8 columns of micromirrors as well as each micromirror corresponds to the control system, the mirrors are linked by pins. The micromirrors are rotated 90 degrees by a grip-and-climb actuator so that the light beam from the input fiber is reflected into the desired output fiber. The switching speed of the optical switch is sub-millisecond. The intervening loss of this optical switch is high, up to 19.9 dB. MOEMS optical switches are still in the research stage and are not industrialized. With the development of optical communication technology and the expansion of network bandwidth, MOEMS optical switches will receive more and more attention and have important research value and broad application prospects.
In addition to MOEMS optical switches, MOEMS devices used in optical networks are fiber optic switches, optical cross-connect devices, wavelength-division multiplexing/demultiplexing, tunable filters, dispersion compensators, optical couplers, etc. The U.S. Defense Advanced Research Projects Agency (DARPA) and the U.S. Department of Defense (DOD) have developed a series of optical switches that can be used in optical networks. The U.S. Defense Advanced Research Projects Agency (DARPA) for MOEMS research attaches great importance to MOEMS technology and its applications around a series of research programs, such as beam flexibility control (STAB) system, optical micro-networks, ultra-large-scale integrated optics, processing optical wavelengths and spatial signals program, high-definition systems program, based on the soldier system MOEMS technology development program. development programs, etc., only a few of which are described here.
■ Beam Flexible Control (STAB) system STAB program is to develop a chip-level beam manipulation elements, the purpose is to develop small, lightweight laser beam control technology to replace the optical communications and infrared countermeasures in the large, mechanically controlled lens system. The program can be used to solve the problem of narrow directional angles of laser beams in laser communication systems, which affects the practicality of laser communication systems. The overall goal of the program is to achieve a 30-fold reduction in the size and 60-fold reduction in the weight of the beam flexible control system.
■Optical micro-networksThe program focuses on affordable demonstrations of high-speed optical data networks with practical applications in aircraft and warships. It has been demonstrated to synthesize a vertical cavity laser into the top of the drive electronics and combine it with the necessary micro-optics to form an optical connection. This was then scaled up to a 16 x 16 dexterity cell array optical communication block for chip-to-chip communication demonstrations. In terms of real-world flight tests, flight tests of a 10 Mbps optical network were conducted through a live-fire exercise utilizing an AV-8B aircraft.
■■ The purpose of the ultra-large-scale integrated optics program is to use optical links instead of electronic links for chip-to-chip and board-to-board communications, so that the data transfer rate between circuit boards reaches terabits per second, which is conducive to high-speed data processing such as synthetic aperture radar and automatic target recognition, and which can reduce the volumetric power of these systems by a factor of 100 to 1,000. As planned, its dexterous image element array will be scaled up to 100×100 and demonstrate data processing for synthetic aperture radar.
DARPA study that MOEMS applications in defense include the following seven areas: weapons guidance and personal navigation chip on the inertial navigation portfolio; armament tracking, environmental monitoring, security surveys unattended distributed sensor systems; small analytical instrumentation, hydraulics and pneumatics, propulsion and combustion control of the integrated flow system; replacement of the current warhead system with improved safety Weapons safety restoration, safing and fuzing for replacement of current warhead systems and improved safety and reliability; embedded sensors and actuators for conditioned maintenance on mobile vehicles and carriers, on-demand structural strength enhancement in light weapons systems/platforms and disaster-resistant buildings; mass data storage devices and systems for gigabyte per square centimeter storage density; integrated micro-optomechanical devices for friend-or-foe identification, displays and fiber optic switches/regulators; integrated micro-optomechanical devices for aircraft, adaptive optics, and other applications. devices; active, *** shaped surfaces for aircraft, adaptive optics and precision components and materials handling. Optical communications and optical remote sensing are the main applications of MOEMS in space.
Micro/nano-satellite networking when the communication between satellites if through the ground station, the noise interference and low power and other reasons will affect the transmission quality. The solution is to use optical communication, which has a large transmission capacity (theoretical value of up to 7.5 Gbps), high transmission rate, wide bandwidth, and does not occupy the radio wave band. Satellites use optical scanners, which can be used to accomplish inter-satellite network capture, targeting and tracking because of their small size, large turning angle, small scattering and high frequency. The U.S. Department of Space has included space optical communications in the "New Century" program and "deep space system technology" program. With the maturity of MOEMS products, it is possible to micro-optical components, micro-adjusters, light sources, detectors and processing circuits integrated on the same chip, composed of a variety of specialized free space optical platform, thus realizing the miniaturization of optical platforms. At present, the Jet Propulsion Laboratory of the U.S. Department of Aeronautics and Space has assembled multiple MOEMS and processing circuits into a multi-chip optical communication module. A module for low-power optical modulation and beam control researched abroad has a size of 10 cm × 10 cm × 2 cm, a mass of only 0.4 kg, and a power consumption of less than 5 watts.
With the microminiaturization of satellites, the aperture and the available space of the optical system for various optical instruments used for attitude determination, autonomous navigation, scientific imaging and imaging spectroscopy techniques are rapidly decreasing. To this end, on the one hand, the size of the optical system can be reduced by using MEMS technology manufactured microlens arrays, micro-diffractive elements, micro-optical scanners and fiber-optic photoreceptor plate, etc.; on the other hand, the micro-optical components, micro-mechanical components, detectors and processing circuits can be integrated building-block type modules to further reduce the size. Jet Propulsion Laboratory completed for optical navigation and imaging science of the basic optical building block type module, the size of 10 cm × 10 cm × 16 cm, the mass of only 0.17 kg, power consumption of less than 0.3 watts. The wide-field star tracker developed by Lawrence Livermore National Laboratory in the United States in collaboration with OCA Applied Optics has a very wide field of view (28 degrees x 43 degrees), can find the center point of a bright star within 50 milliseconds, and can track a target with a high accuracy of 20 microradians (3σ value). The star tracker, including microelectronic circuits, has a mass of only 175 grams and consumes 3 watts of power.