Effect of the incident light beam conditions, such as the beam profile, the beam size, and the incident angle on the beam propagation and the firing characteristics of the radial-firing optical fiber tip comprised of conically shaped air pocket was investigated by the simulation using the ray-tracing method. Regardless of the different Gaussian profiles of the incident beam, no significant difference in the maximum firing angle but a little increase in the firing power was found with the increase of the axial distance of the Gaussian profile. With the increase of the incident beam size, no significant difference in the maximum firing angle was found but the relative firing power decreased and the extent of the power decrease depended on the numerical aperture (NA) of the fiber. On the other hand, the incident beam angle (BA) dependence of the firing power was significant, decreased to 65.9% and 31.9% for the RFF tip of NA 0.12 and NA 0.22, respectively, with the increase of the incident BA from 0 deg to 12 deg but the maximum firing angles did not show much decrease, smaller than 5 deg. The present modified simulation considering the incident light beam size and angle clearly showed the very close power distribution of the firing beam with respect to the firing angle obtained by the experimental results.
In this study, highly Dy3+-doped germano-borate glasses for different dopant concentrations ranging from 20 to 30 mol% were fabricated and their physical, optical, and MO properties were investigated. The characteristic thermal parameters disclosed good thermal stability of <100 °C against crystallization in the studied glasses. In addition, the glasses showed a high optical transmission of ~ 85% in the NIR region of 1550 nm. A very large Verdet constant of approximately -5.36 rad/(T·m) at 1550 nm was obtained in the glass containing 30 mol% Dy2O3. Therefore, this glass might be a promising MO material for applications in the NIR region.
Active gain fiber is a critical component to realize fiber laser sources for various applications such as cutting, welding and other material processing. To meet the requirement for various laser applications, the power scaling of fiber lasers is still concern, where active gain fiber is very important. There are several fabrication technologies for active fibers with low NA, large core diameter and high absorption, which characteristics for high power lasers are typically required. Here, novel fabrication technology based on VAD (Vapor Axial Deposition) for active fibers is introduced.
We report a large-core radial-firing optical fiber tip comprised of conically shaped air-pocket, fabricated by deforming a hollow optical fiber fusion-spliced with the large-core optical fiber (LCF) (core/cladding diameters = 200 / 220 μm) using the arc-discharge method. The effect of the intaglio air-pocket angle and the numerical aperture (NA) of the LCF on the radial-firing characteristics of the fiber tip was investigated. The design of air-pocket of the fiber tip was optimized for an effective radial-firing by simulating the beam profile of the radial-firing optical fiber with the ray-tracing method. The 45 deg of the conical angle with the low NA (0.12) of the LCF has shown the maximum radial-firing angle of 81 deg by the simulation. The fabricated LCF tip with the intaglio conical air-pocket with the 45 deg angle has shown the radial-firing angle up to ±78 deg, which was in good agreement with the simulation results. The present LCF radial-firing tip can be an effective element of medical devices for treatment of tubular shape tissues with the high-power transmission and the ease of operation in vivo.
A novel photonic crystal fiber with a Ge nanoparticles-doped germano-silicate core was fabricated by using the MCVD and stack-and-draw processes. Effect of Ge nanoparticles and the air-holes structure on non-resonant optical nonlinearity and supercontinuum generation was investigated.
Effect of fluorine (F) doping in the core of a birefringent photonic crystal fiber (PCF) on sensing capability of temperature and strain was investigated by using Sagnac loop interferometry. The birefringence of the F-doped PCF was measured to be 1.5610-4 at 1550 nm and the temperature and the strain sensitivities of the F-doped PCF were found to increase from -9.6 pm/°C/m to -3×4 pm/°C/m and from 3.5 pm/με to 6.3 pm/με, respectively.
Possibility of a Co/Fe co-doped alumino-silicate optical fiber as a radiation dosimeter application was investigated from the measurement of radiation-induced optical attenuation (RIA). The RIA at 1310 nm of the optical fiber upon gammaray irradiation was found to increase linearly with the radiation dose. The extent of the RIA increase to 11,900 dB/km at radiation dose rate of 20 Gy/min for 1 hour was 70 times larger than that of the reference single mode fiber and the RIA remained almost constant after 5 minutes of the irradiation termination.
An optical fiber bend sensor based on a fiber Bragg grating by using a germano-silicate glass optical fiber with depressed-index structure has been developed and its novel bend sensing characteristics was demonstrated. With the increase of bending, the transmission spectrum was linearly blue-shifted without change of optical transmission loss. Total blue-shift of the Bragg reflection wavelength upon bending in the radius of curvature from 20 m-1 to 133 m-1 was − 0.13 nm.
To investigate the nonlinear optical properties of metallic nanoparticles in dielectric composite
materials, germano-silicate glass optical fibers incorporated with gold nanoparticles were made by
using modified chemical vapor deposition technique and solution doping process. The incorporation
of the gold nanoparticles was confirmed by the sharp absorption peak appeared near 498.4nm, which
was due to the surface plamon resonance absorption of Au nanoparticles. Resonant optical
nonlinearities of the fibers were estimated by measuring the peak shift of the fringes obtained from
the long-period fiber grating pair upon pumping with Argon laser at 488nm. The resonant nonlinearity
was found to be 5.00x10-16m2/W by the incorporation of the gold metal concentration and with the addition of Al3+ ions.
We present a simple analytical model to approximately analyze the TDFA for silica glass as well as fluoride glass based
optical fibers. We have verified the validity of method using the in-house fabricated Tm-doped alumino-germano-silicate
glass fiber as well as reported results for the Tm-doped fluoride glass fiber. The spectral variation of gain
obtained with the silica glass fiber TDFA after pumping with pump power of 275 mW at 1064 nm showed good
agreement between the simulated and the measured values. The pump power dependence of gain in the fluoride glass
fibers calculated by our method also showed a good agreement with the experimental results reported. The maximum
error in determination of gain was limited to 12%.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.