Graphene Oxide Absorber Research Articles

Investigation of substrate materials for graphene oxide absorber loaded antenna array increased ambient temperature

Integration of electromagnetic (EM) wave absorber with patch antenna array on single substrate provides a very efficient way to improve the radiation pattern of array by reducing mutual coupling effect. The placing of absorber on array assembly may however affect the radiation characteristics due to the heat generated from absorbed power. As the microwave absorber dissipates the inter-element waves in terms of heat via absorption, the ambient temperature of array increases which consequently varies the patch dimensions and dielectric properties of the substrate thus shifting the resonant frequency of array. These effects have been investigated for graphene oxide-based absorber loaded rectangular patch array designed on different substrates such as silicon, gallium arsenide, aluminium oxide and Roger RO3210. On the basis of percentage variation in return loss and effective bandwidth an optimum substrate is proposed which undergoes minimize temperature effect without deteriorating the gain and directivity of the antenna array. The results show that for Graphene oxide-based absorber with Roger RO3210 substrate having high melting temperature of 4236.85 °C, side lobe level of array is reduced from 3.737 dB to 2.551 dB with increased major lobe gain. Due to absorbed power, ambient temperature of array increased from room temperature (27 °C) to 187 °C significantly shifting the resonant frequency from 10.4 GHz to 8.9 GHz. Further the comparison results show that with aluminium oxide substrate the array exhibits minimum temperature sensitivity hence proving to be a better choice for design of microwave absorber loaded antenna array.

763fs Passively mode-locked Yb:Y2SiO5 laser with a graphene oxide absorber mirror

Based on a graphene oxide absorber mirror, the laser-diode pumped mode-locked Yb:Y2SiO5 (Yb:YSO) laser was demonstrated for the first time. The laser generated pulses with pulse duration as short as similar to 763 fs and average output power of 700 mW at the central wavelength of 1059 nm. The corresponding peak power and energy of a single pulse were similar to 8.6 kW and similar to 7.4 nJ, respectively. To our best knowledge, this is the shortest bulk mode-locked laser based on graphene oxide. (C) 2014 Elsevier Ltd. All rights reserved.

Reflective graphene oxide absorber for passively mode-locked laser operating at nearly 1 μm

A low cost and simply fabricated reflective graphene oxide is successfully made. By using this absorber, as well as an end reflector, we obtain a passively mode-locked Yb:LuYSiO5 laser operating at nearly 1 μm. When the pump power is increased up to 5.73 W, stable mode locking is achieved. The central wavelength of the laser spectrum is 1043.2 nm with a pulse duration of 5.0 ps. When the pump power reaches 8.16 W, dual-wavelength mode locking laser pulses at 1036.3 nm and 1043.5 nm are simultaneously detected.

Passively Q-Switched and mode-locked Nd:YVO4 laser with sandwich structured wallpaper graphene oxide absorber

We report on a passively Q-switched and mode-locked Nd:YVO4 laser using a novel low-cost wall-paper graphene oxide absorber. Sandwich structured wallpaper graphene oxide absorber was constructed by a high transmission mirror, a piece of wallpaper graphene oxide absorber and a reflective mirror. The average output power of 310 mW of passively Q-switched and mode-locked laser was successfully achieved. The repetition rate and pulse width of the Q-switched envelope were 213 kHz and 770 ns, respectively. The repetition rate of passively mode-locked pulse within the Q-switched envelope was 81.3 MHz with the pulse energy of 3.8 nJ.

A highly efficient graphene oxide absorber forQ-switchedNd:GdVO4 lasers

We demonstrated that graphene oxide material could be used as a highly efficient saturable absorber forthe Q-switched Nd:GdVO4 laser. A novel and low-cost graphene oxide (GO) absorber was fabricated by a verticalevaporation technique and high viscosity of polyvinyl alcohol (PVA) aqueous solution. Apiece of GO/PVA absorber, a piece of round quartz, and an output coupler mirror werecombined to be a sandwich structure passive component. Using such a structure, 104 nspulses and 1.22 W average output power were obtained with the maximum pulse energy at2 µJ and a slope efficiency of 17%.