High power direct diode lasers have made significant impact in the industry as an alternative heat source for material processing. In order, to be readily adopted by the industry they have to show >99% uptimes. One of the much-discussed issues associated with copper based micro channel coolers has been the lifetime of the micro channel cooler in High Power Direct Diode Laser (HPDDL) systems. HPDDLs with micro channel coolers have shown long life in some installations, but have shown to work only a few thousands of hours in others. These have been attributed to the erosion, corrosion, or clogging of the micro channel coolers. This paper will describe the proper design of the water system for use with a micro channel cooled laser system. This paper focuses on the water chemistry and its impact on erosion and corrosion of the copper based micro channel coolers. Using previously reported data; we will give erosion rates for different water chemistries.
As tools for use in industrial applications, High Power Direct Diode Lasers [HPDDL], also known as semiconductor lasers, are becoming more prevalent as a heat source for industrial applications. Diode laser technology has now been used in production for a number of years. Their unique beam shape, low ownership cost, high efficiency (~60%), and compact design make them an economic alternative to traditional heat technologies for heat treating and cladding of overlay operations. The benefits of using HPDL for laser surface transformation hardening and cladding are discussed.
Direct diode laser will become much more prevalent in the solar system of manufacturing due to their high efficiency, small portable size, unique beam profiles, and low ownership costs. There has been many novel applications described for high power direct diode laser [HPDDL] systems but few have been implemented in extreme production environments due to diode and diode system reliability. We discuss several novel applications in which the HPDDL have been implemented and proven reliable and cost-effective in production environments. These applications are laser hardening/surface modification, laser wire feed welding and laser paint stripping. Each of these applications uniquely tests the direct diode laser systems capabilities and confirms their reliability in production environments. A comparison of the advantages direct diode laser versus traditional industrial lasers such as CO2 and Nd:YAG and non-laser technologies such a RF induction, and MIG welders for each of these production applications is presented.
We propose the utilization of a Smart In-Package [Micro] ALigner (SIMPAL) to enable fiber optical sensors for thick walled composite structures. Fiber optic coupling is the barrier preventing single mode and multimode fiber optical sensors systems from being incorporated into composite structures. A fiber optic connector that has a MEMS in-package micro aligner, integrated optical detectors, and control electronics is proposed to overcome the incompatibility between structural manufacturing tolerances and fiber optic alignment tolerances. The SIMPAL technology will enable affordable optical connection with sub-micron alignment tolerances to be made after the fiber optics are machined off at the egress point during a standard trimming process. We have demonstrated and described the MEMS actuator part of the SIMPAL. This active part is a 3-axis active fiber optic micro-aligner small enough to fit into current electro-optical packages. The micro-aligner is fabricated on a silicon wafer with the high aspect MEMS/LIGA process technology. The electrically controllable actuators demonstrate the high force and displacements necessary for in-package alignment of a micro-optics. The integration of lenses, optical sensors and control electronics is proposed to realize a smart optical backplane interconnect system.
We describe and demonstrate what we believe is the first 3- axis MEMS active fiber optic micro-aligner, which will allow for in-package alignment of fiber optic and micro-optic components. The micro-aligner is a wafer level fabricated device, based on a combination of silicon micromachining and LIGA technology. The electrically controllable actuators demonstrate the high force and displacement necessary to overcome fiber optic, counterforce springs, friction, and wirebonds to perform in-package alignment of a fiber optic. We have demonstrated movement of > 20 microns in all three axes in an in-package configuration. The first prototype device are currently small enough (4 X 4 X 0.5 mm3) to fit into a standard 14 pin butterfly package. We will show that future devices with the same forces and displacements can be made smaller than 1 X 1 X 0.5 mm3 thus allowing for multiple single mode fiber optic attachments inside a standard opto-electronic package.
Satellite programs are moving in the direction of smaller and lighter structures. Technological advances have permitted more sophisticated equipment to be consolidated into compact spaces. Micro-satellites, between 10 and 100 kg, will incorporate micro-electric devices into the lay-up of the satellite structure. These structures will be designed to carry load, provide thermal control, enhance damping, and include integrated passive electronics. These multifunctional structures offer lighter weight, reduced volume, and a 'smarter' overall package for incorporation of sensors, electronics, fiber optics, powered appendages or active components. McDonnell Douglas Corporation (MDC) has applied technology from the synthesis and processing of intelligent cost effective structures (SPICES) and independent research and development (IRAD) programs to the modular instrument support system (MISS) for multifunctional space structures and micro-satellites. The SPICES program was funded by the Defense Advanced Research Projects Agency (DARPA) to develop affordable manufacturing processes for smart materials to be used in vibration control, and the MISS program was funded by NASA-Langley. The MISS program was conceived to develop concepts and techniques to make connections between different multifunctional structures. MDA fabricated a trapezoidal carbon composite structure out of IM7/977-3 tape prepreg. Flex circuits, thermal and optical conduits were embedded to realize a utility modular connector. These provide electrical, thermal, optical and mechanical connections between micro- satellite components. A quick disconnect mount was also developed to accommodate a variety of devices such as solar arrays, power sources, thermal transfer and vibration control modules.
A demonstration of the capabilities of an active AlGaAs based 1 X 10 photonic coupler is presented along with an Optically Coherent Frequency-Domain Reflectometer (OCFDR) Fabry-Perot demodulation system. The increased capability of the active 1 X 10 photonic coupler allows for the simultaneous multiplexing and demodulating of up to ten parallel Intrinsic Fabry-Perot Interferometric (IFPI) fiber optic sensors. A demonstration of the amplification and switching ability of the photonic device is also presented along with a comparison of the active photonic device with current polarization preserving fiber optic couplers. Future developments and improvements of photonic devices and their effect on future fiber optic sensors systems will also be discussed.
An integrated phase modulator/signal multiplexer has been demonstrated that can be used to demodulate a fiber optic interferometer's output. The phase demodulator/optical switches are monolithically integrated with an active 1 X 10 photonics polarization preserving coupler. This device was fabricated with rib waveguides and etched-facet turning mirrors. Active multiplexing and demultiplexing of a fiberoptic interferometer has also been demonstrated using the active photonics chip. The active photonics demodulation/multiplexing system offers the advantage of nearly lossless splitting and functionality in an extremely small package size.
1.1 W cw has been achieved from a 10-amplifier coherent array with an electrical to optical conversion efficiency of 28%. The amplifiers were injected with 20 mW from a master oscillator via a single-mode polarization-preserving optical fiber. Approximately 90% of the output power from the amplifier array was locked to the master oscillator's frequency.
The performance of AlGaAs/GaAs GRIN-SCH-SQW ridge waveguide amplifiers has been characterized as a function of the rib-width, the amplifier bias and the master oscillator injection power. The results of this study revealed that the mode width is weakly dependent on the rib-width, the bias voltage increases with the injection signal level, and the 3 dB gain bandwidth is approximately 45 nm.
Recent advances in the development of a 10-amplifier active integrated-optic device are reviewed. High coherence is demonstrated for the array, which integrated power splitters, turning mirrors, phase modulators, and optical amplifiers on a single chip. Techniques for controlling the most significant parameters, the rib dimensions and the turning mirror roughness, are described. The performance of the various component and integrated devices is discussed.
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