CO2 laser polishing of conical shaped optical fiber deflectors

A novel method for polishing conical shaped optical fiber deflectors by modulated CO2 laser exposure is reported. The conical shaped fiber deflector geometry was first formed with rough mechanical polishing, then it was exposed to modulated CO2 laser operating with wavelength at 10.6 µm to achieve fine polish surfaces. The motivation of this work is to demonstrate that the modulated CO2 laser exposure approach allows a fiber surface roughness at a nanometer scale without modifying the conical shape of the fiber deflector. The average surface roughness of mechanically polished fiber deflectors with 30 and 9 µm lapping films was smoothed down to 20.4 and 4.07 nm, respectively, after CO2 laser polishing process. By combining mechanical and laser polishing techniques, fabrication of conical shaped optical fiber deflectors takes less time and it becomes laborer independent and easy to apply. © 2017, Springer-Verlag Berlin Heidelberg

A twisted shaped cladding light stripper by CO2 laser processing for high power fiber lasers and amplifiers

Applications of high power lasers and amplifiers have been increasing because of its superior properties such as high wall-plug efficiency, excellent beam quality, and reliability [1]. Despite advances in high power fiber components, there is still component reliability based challenges on extraction process of unwanted cladding light [2]. There are several techniques to extract the cladding light from the fiber laser system such as high index polymer coating that of working principle is violating the total internal reflection [2], roughened cladding surface which uses the scattering to eliminate the cladding light [3], soft metal coating to absorb the cladding light [4] and CO2 laser processing of cladding to disturb the light path with the structural manipulations and strip the unwanted light from these structures. There are some limitations for each case. The high index polymer CLS are limited by the thermal degradation of recoated polymer [4]. For the roughened or etching CLS, even though very high attenuations levels were achieved, the roughing or etching process decrease the fiber strength. This could create undesired problems such as heat localization and microcrack formation on cladding wall. Here, we present novel method for practical, robust, compact, and all glass cladding light stripper fabrication on Ytterbium (Yb) doped octagonally shaped double clad fiber (DCF)

A reconfigurable RF MEMS triple stub impedance matching network

This paper presents a reconligurable triple stub impedance matching network using RF MEMS technology centered at 10GHz. The device is capable of covering impedances on the whole Smith Chart. The device structure consists of three variable length stubs which are designed as distributed MEMS transmission lines and two lambda(g)/8 length CPW transmission fines connecting the stubs. The variable length stubs are implemented with 12 MEMS switches over CPW lines and CPW lines connecting the switches. lambda(g)/8 spacing between the stubs is selected to obtain a uniform distribution of the impedance points on the Smith Chart. Initial measurement results of the fabricated structure show a good agreement with the simulation results

Investigation of on-wafer TRL calibration accuracy dependence on transitions and probe positioning

This paper presents the effects of various transition types from the measurement plane to the reference plane in TRL calibration and probe positioning effects for on wafer measurements of CPW based devices. Fourteen different transition types, with direct, linear and exponential transitions, including 3 different variations of ground-signal-ground (GSG) spacing are examined. To observe the performance of the transitions, simple CPW transmission lines of different characteristic impedances are fabricated using standard lithography techniques on glass substrate and S-parameters are measured in 4.5-20 GHz band. Results are compared with electromagnetic simulations. The effects of probe misplacement along the lateral and horizontal axis are also investigated