tailieunhanh - Apodization technique for fiber grating fabrication with a halftone transmission amplitude mask

Not all materials can be etched in an easy and cheap way. Especially, noble metals or tantalum are stable against most of these corrosive structuring methods. Hence, precision machining may be used to generate microstructures from these metals as well as from standard metal alloys such as stainless steel or hastelloy. Depending on the material, precision machining can be performed by spark erosion (wire spark erosion and countersunk spark erosion), laser machining or mechanical precision machining. In this case, mechanical precision machining means milling, drilling, slotting and planning. Although themachining technology used is comparable to the techniques well known from conventional dimensions in the millimeter range or above, the. | Apodization technique for fiber grating fabrication with a halftone transmission amplitude mask Stephen J. Mihailov Francois Bilodeau Kenneth O. Hill Derwyn C. Johnson Jacques Albert and Andrew S. Holmes Experimental results of fiber Bragg gratings fabricated with halftone amplitude transmission masks and 10-cm-long phase masks are presented for the first time to our knowledge. The performance of the devices is evaluated in terms of their spectral characteristics and deviation from linear group delay. Good out-of-band sidelobe suppression of 27 dB and group-delay ripple of ps is achieved for fully apodized grating devices. 2000 Optical Society of America OCIS codes . 1. Introduction Fiber Bragg gratings FBG s have proven themselves to be cost-effective fiber-compatible devices for use in optical network systems. They have certain advantages over other passive components such as interference lters or arrayed waveguide technology in that any desired spectral pro le and dispersion characteristic can be easily generated by means of controlling the FBG grating pitch apodization and device chirp. Precise control of the reflection bandwidth makes FBG s strong candidates for dense wavelength division multiplexing DWDM applications such as channel When its dispersion characteristic and chirp are tailored a FBG can be used to compensate for the chromatic dispersion in optical ber communication When a nite-length FBG has a uniform modulation of its index of refraction the main peak or Bragg resonance lBr in the reflection spectrum is accompanied by a series of sidelobes at adjacent wavelengths. In DWDM-type applications in which high rejection of nonresonant light is required it is important to lower the reflectivity of the sidelobes or to S. J. Mihailov F. Bilodeau K. O. Hill D. C. Johnson and J. Albert are with the Department of Optoelectronic Technologies Communications Research