Luminescence of phosphorus doped silica glass

Abstract

A fiber preform with P-doped silica core is studied by luminescence methods. P-doped silica was synthesized via the SPCVD method on a substrate tube made of pure silica glass F300. Two luminescence bands were detected under excitation of the F2 excimer laser (157 nm). One band is in UV range at 4.6 eV (265 nm) with two time constants ~30 ns and 5 μs and the other at 3.1 eV (400 nm) with time constant ~5.5 ms. Fast decay of the blue band with time constant ~20 ns was also observed. The main excitation band of the UV luminescence is at 7.1 eV (~170 nm) and that for blue band is at 6.3 eV (~195 nm). These bands belong to two different luminescence centers, however, both are associated with the presence of phosphorus. The UV band is similar to the one observed in many different oxide materials containing phosphorus and is ascribed to PO 3 4 complex ion. The blue band is ascribed to a twofold coordinated phosphorus. Both the blue and the UV luminescences participate in the recom-bination process due to electron trapping. These luminescences appear due to thermal stimulation upon recombination of liberated self-trapped holes. Other than the detected phosphorus-related oxygen-hole-centers, there is no other recombination luminescence.

v-P2O5 micro-clustering in P-doped silica studied by a first-principles Raman investigation

“…Hence the latter Raman band has to be regarded as a fingerprint of the presence of corner-sharing phosphate tetrahedra (P 2 ) even at low P content. This fact might be relevant also in explaining conversion mechanisms as well as luminescence properties of point defects in P-doped glasses 25,26,63 . Furthermore, the present results could pave the way for the development of new codoping strategies aiming at separating phosphate tetrahedra so to reduce the number of generation and conversion processes leading to the formation of P 1 centers which are the main responsible for the attenuation of the signal at wavelength of 1550 nm in high power optical fiber amplifiers 27 .…”

“…A detailed understanding of the way P 2 O 5 is included at microscopic levels within the silica network is highly desirable for the study and exploitation of all point defect (“centers”) related properties 24–26 and phenomena such as photo- and radiation-darkening in optical fibers 13–17,27 . Specifically, by means of electron paramagnetic resonance (EPR) investigations it has been established that two variants of the so-called phosphorus oxygen hole center (POHC) exist in irradiated P-doped silica: the room temperature POHC (r-POHC) and the low temperature POHC (l-POHC) 25,28,29 .…”

Review of bismuth‐doped fibers used in O‐band optical amplifiers‐scientific challenges and outlook

“…22 This is one of the key reasons for BDF to have such broad luminescence. P-doped silica fibers typically have structural defects that contains phosphorous, including paramagnetic centers like P1, P2, P4 and phosphorus-oxygen-hole center, 6,23 as well as diamagnetic defects like [(O−) 2 P( = O) 2 ] − . 24 These defect structures, especially the ones with negative charge or lone pair electrons, can become the preferential sites for bismuth ions in the glass matrix.…”

“…The phosphorous co‐dopant is critical for bismuth species to generate O‐band luminescence. Fibers doped with only P do not have significant near infrared (NIR) emission 6 . Other commonly available dopants used in silica fibers such as germanium and aluminum shift the luminescence of bismuth species to other spectral bands 7 .…”

“…Fibers doped with only P do not have significant near infrared (NIR) emission. 6 Other commonly available dopants used in silica fibers such as germanium and aluminum shift the luminescence of bismuth species to other spectral bands. 7 It is noted that such drastic shift of emission peaks due to co-dopants are not observed in rare-earth doped fibers.…”