This paper reports the parameters that affect the fabrication of Flat Fibers, including preform size and doping, furnace temperature, preform feed speed, fiber drawing speed, fiber dimension, fiber quality and shape, vacuum pressure and core dimension. The feed and draw speed generally follows the simplified mass conservation law to draw the fiber to a specific dimension. The preform wall thickness affects the vacuum pressure and furnace temperature that is needed to 'flatten' the fiber. The preform wall thickness is directly proportional to the volume of glass inside the neck-down region. The wall thickness of the preform and its dopant will also affect the size of the cladding and core dimension. Finally, some issues associated with the fabrication of Flat Fibers are also observed and discussed, including fabrication of Flat Fibers with non-uniform dimensions, deformed shapes, unwanted airholes and poor quality of the Flat Fibers.
The rapid growth of information technology is closely linked to our ability to modulate and demodulate a signal, whether in the frequency or in the time domain. Recent demonstrations of terahertz (THz) modulation involve active semiconductor metamaterial surfaces or use of a grating-based micromirror for frequency offset tuning. However, a wideband and active differentiator in the THz frequency band is yet to be demonstrated. Here, we propose a simple method to differentiate a THz pulse by inducing tiny phase changes on the THz beam path using a piezoelectric micromachined ultrasonic transducer array. We precisely demonstrate that the modulated THz signal detected after the piezoelectric device is proportional to the first-order derivative of the THz pulse. The proposed technique will be able to support a wide range of THz applications, such as peak detection schemes for telecommunication systems.
A new method of fabricating multicore flat fiber (MCFF) is proposed. A 40-m long, 230-µm × 670-µm MCFF with six cores arranged in one row is demonstrated with polymer coating. The fabricated fiber with and without polymer coating can tolerate down to 1 and 2 cm of bending diameter, respectively. The intercore crosstalk over 40 m of MCFF is shown to be less than -74 dB. This method significantly simplifies fabrication of MCFF and provides rapid and flexible manufacturing of km-length MCFF for telecommunication applications.
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