Investigation on stimulated Brillouin scattering characteristics in a highly doped Bismuth-based Erbium-doped fiber

Stimulated Brillouin scattering (SBS) characteristics in a 49 cm long highly doped Bismuth-based Erbium doped fiber (Bi-EDF) is investigated in the ring and linear cavity configurations. At Brillouin pump (BP) power of 6 dBm, the Brillouin laser peak power of the optimized ring Brillouin Erbium fiber laser (BEFL) is obtained at 23 dB higher than the peak power of the conventional linear cavity at an up shifted wavelength of 0.08 nm. This Bi-EDF ring cavity operates at nearly 1563 nm wavelength region, which is up-shifted by 0.08 nm from the Brillouin pump wavelength with the side mode suppression ratios (SMSR) of 29 and 23 dB in the forward and backward directions, respectively.     

Photonic crystal ber-based multi-wavelength Brillouin ber laser with dual-pass ampli cation con guration

A simple technique for achieving a stable, room temperature and multi-wavelength lasing with narrow linewidth is demonstrated using Brillouin ber laser (BFL) with a 100-m-long photonic crystal ber (PCF) in conjunction with a dual-pass configuration. A broadband ber Bragg grating (FBG) operating in the C-band region is incorporated at the end side of the setup to allow a dual-pass operation. The proposed BFL can operate at any wavelength depending on the Brillouin pump wavelength and the FBG’s reflection region used. With a Brillouin pump (BP) of 15.7 dBm, approximately 7 Stokes and 4 anti-Stokes lines are obtained with a line spacing of 0.08 nm.     

High-resolution Fresnel zone plate fabrication by achromatic spatial frequency multiplication with extreme ultraviolet radiation

We used an approach based on the self-imaging property of gratings to fabricate high-resolution Fresnel zone plates (FZPs). Under certain conditions, the illumination of a parent ZP with a wideband EUV beam produces a radially oscillating intensity distribution with double the spatial frequency of the ZP. This intensity distribution is observed in a certain distance range, given by the local zone width, the focal length of the ZP, and the spectral bandwidth of the illuminating beam. This phenomenon has been used to lithographically record daughter ZPs that have approximately half the zone width, thus twice the resolution, of the parent ZP. FZPs with zone widths as low as 30 nm have been fabricated in this way. Use of this technique in the extreme ultraviolet (EUV) region has the potential for high throughput production of FZPs and similar high-resolution diffraction optics with variable spatial frequency for the EUV and x-ray regions.     

Q-Switched Fiber Laser with a Hafnium-Bismuth-Erbium Codoped Fiber as Gain Medium and Sb2Te3 as Saturable Absorber

Journal of Russian Laser Research - We successfully demonstrate Q-switched fiber laser with a 20 cm long Hafnium-Bismuth-Erbium codoped fiber (HBEDF) as an active medium in conjunction with...     

Positive parity states and some electromagnetic transition properties of even-odd europium isotopes

The positive-parity low-spin states of even-odd Europium isotopes (^151–155Eu) were studied within the framework of the interacting boson-fermion model. The calculated positive low-spin state energy spectra of the odd Eu isotope were found to agree quite well with the experimental data. The B(E2) values were also calculated and it was found that the calculated positive-parity low-spin state energy spectra of the odd-A Eu isotopes agree quite well with the experimental data.     

High output power Erbium-Ytterbium doped cladding pumped fiber amplifier

The performance of a high output power Erbium-Ytterbium doped fiber amplifier (EYDFA) pumped by a 927 nm laser diode are proposed and experimentally investigated. The EYDFA provides a flat gain and output power higher than 23 dBm in the wavelength region from 1545 to 1566 nm using a double-pass configuration. A broadband fiber Bragg grating is used in the double-pass EYDFA to allow a double-propagation of the test signal in the gain medium and thus improves the gain and output power characteristics of the amplifier. The maximum output power of 390 mW is obtained at the maximum 927 nm pump power of 4.1 W which translates to a power conversion efficiency of about 10%.     

Effect of injection of C-band ASE on L-band erbium-doped fiber amplifier

The effect of injecting conventional band (C-band) amplified spontaneous emission on the performance of long-wavelength band erbium-doped fiber amplifier (L-band EDFA) is demonstrated. It uses a circulator and broadband fiber Bragg grating (FBG) to route C-band ASE from a C-band EDFA. Injection of a small amount of ASE (attenuation of 20 dB or above) improves the small signal gain with a negligible noise figure penalty compared to that of an amplifier without the ASE injection. A maximum gain improvement of 3.5 dB is obtained at an attenuation of 20 dB. At very large amounts of ASE injection (attenuation of 0 dB), the gain of the amplifier is clamped at 15.2 dB from ?40 to ?10 dBm with a gain variation of less than 0.3 dB. The saturation power is also increased from ?8 dBm (for without ASE injection) to 2 dBm (VOA=0 dB) with a slight noise figure penalty. These results show that the ASE injection technique can be used either for gain improvement or for gain clamping in L-band EDFA.     

Extraordinary optical transmission in the ultraviolet region through aluminum hole arrays

We investigated the extraordinary optical transmission phenomenon in the UV range by fabricating large-area, free-standing aluminum hole arrays using extreme UV interference lithography and shadow thermal evaporation. Transmission spectra show strong peaks in the UV region resulting from both surface plasmon polariton and localized surface plasmon excitations. The results indicate that the high plasmon frequency of Al is directly responsible for the presence of strong resonance peaks in the UV region, which supports the role of plasmonic phenomena in the extraordinary transmission. The simple fabrication method enables large-area production of such structures for research and industrial production purposes.     

Theoretical and experimental studies on coupler based fiber optic displacement sensor with concave mirror

A new fiber optic displacement sensor (FODS) is proposed and demonstrated using a multimode fiber coupler as a sensor probe and a concave mirror as a reflective target. A mathematical model is also developed to investigate the performance of proposed FODS at various coupling ratio, fiber diameter, and surrounding media. Three slopes are obtained for the displacement response where the third slope starts at a displacement position of twice the focal length. The numerical results show that higher performance is attained at lower coupler ratio of 50:50 or smaller core diameter. The results also show that the proposed FODS has a potential application in liquid and gas chemical sensors. The experimental performances are also investigated for the proposed sensor where it is observed that the second peak of the displacement curve is located at exactly two times of the focal length or 20 mm.