With the development communication, polarization filter, as the key components of communication, becomes more and more important. For satisfying various requirements, the paper studies different photonics crystal fiber (PCF) polarizing devices based surface plasmon resonance (SPR). Besides, we have also demonstrated their excellent polarization performance from two aspects of theory and experiment. On one hand, the paper theoretically proposed dual-wavelength single polarizing filter with the broadband of low crosstalk. It could have single polarizing filtering in the dual-wavelength of 1310 and 1550 nm and the polarization direction of optical output is independent of the wavelength of incident light. The polarization direction of emergent light through filter can always keep the core mode in x-polarized direction (x-PCM) in a wide range of wavelength, which increases the difference of confinement loss of core mode in y-polarized direction (y-PCM) and x-PCM, and reduces mutual crosstalk. On the other hand, considering the new communication waveband emerging, we present a V-type birefringence microstructure optical fiber with embedded dual copper wires that were made by the stack-drawing method and the dual copper wires were aligned in the vertical direction symmetrically. Experimental results showed that the fiber can be easily excited strong SPR in the S and L waveband. Then the core mode is completely coupled into the copper wires and generates the SPR in the y-polarized direction, to achieve the purpose of directional filtering.
With the rapid development of life science, multi-component detection is necessary. In order to monitor the concentration of the biochemical substances simultaneously, a dual-channel biomedical sensor is proposed in this paper. Due to its sensitivity to the surrounding refractive index, there are many applications in biochemical sensing. Surface plasmons are a coupling of electromagnetic oscillations generated by electromagnetic waves and free electrons at the interfaces between metal and dielectrics. Taking into account the different plasma band of different metals, multiple signal peaks can be generated during detection to achieve multi- peak sensing. In addition, when rough analysis is performed on the analysis sample, In order to avoid the complex process of specific sample extraction, multi-component detection of the sample is necessary. Moreover, research on a micro-structured optical fiber sensor based on the plasmon mode interaction of Au/Ag films has been rarely reported. Therefore, a novel dual-channel sensor is designed considering the flexible characteristics of Photonics crystal fiber (PCF) structure, different plasma bands for Au/Ag, and the necessity of multi- component detection. The numerical results show that the core mode in PCF sensor is affected by the Surface plasmon resonance (SPR) at the Au/Ag interface simultaneously, which makes it possible to monitor multiple substances near the Au/Ag films. Meanwhile, the detection of the positive and negative amplitude sensitivities makes the sensor detection stable and it can eliminate certain external disturbances. Its excellent sensing characteristics are of great application value in environmental monitoring, biochemical sensing, etc.
Ytterbium doped microstructured optical fibers have many advantages for fiber amplifiers. Due to air-clad structures, high-power microstructured optical fiber laser systems require stricter end-facet treatment than that of conventional fiber laser systems. Here, we fabricated microlenses in ytterbium doped double-cladding microstructured optical fibers by a CO<sub>2</sub> laser. The surface power density of the MOF tip can be reduced by 2 quantity levels theoretically. The theoretical and experimental investigation is carried out to study effect of minor and major axis semidiameter of ellipsoidal microlenses on coupling efficiency. The experimental coupling efficiency was over 88%. Results indicated that this microlens combines the end cap scheme and pump coupling. The proposed fabrication method is helpful for high mechanical stability, well reproducibility and miniaturization of the high-power rare earth-doped microstructured optical fiber laser systems.
We demonstrate the broadband stimulated emission generation in the Er3 + / Tm3 + / Ho3 + codoped optical fiber rod (ETHOFR). The absorption spectra, broadband emission, energy level, electron transition process, and optical stimulated emission of this codoped material are analyzed. Broadband spectrum amplification from 1.7 to 2.1 μm is observed when ETHOFR is excited by 793-nm laser diode (LD). The optical gain shows similar wavelength in dependence on luminescence properties. This material holds potential in the application of weak optical signal amplification.
In this paper, we demonstrated an experiment of the all Yb-doped photonic crystal fiber laser using free space optical paths method. The experimental setup of all Yb-doped photonic crystal fiber laser is composed of the seed laser and the amplifier. The laser gain medium of the seed laser and the amplifier are the same Yb-doped photonic crystal fibers that are fabricated by non-chemical vapor deposition (Non-CVD) technology. The seed laser cavity is a Fabry-Perot cavity. The amplifier is pumped by back-end method. They are coupled each other by lens and dichroic mirrors on the optical table. The experimental results have a good reference value for the photonic crystal fiber laser research in the future.
An octagonal multicore photonic crystal fiber is proposed. The supermode and its far field distribution have been analyzed by using the full-vector finite element method. In the condition of in-phase supermode, the influences of different wavelengths, air filling fraction, and air hole diameter between cores on normalized intensity of cores are studied. The equal intensity distribution of cores in the output plane is realized. Finally, the effects of changing the air hole diameter between different cores on the effective mode area and confinement loss are investigated. The results show that the effective way to change the relative intensity between cores is to resize the air holes between different cores. If this parameter is changed, a better intensity distribution with large effective mode area and low confinement loss for propagation is obtained.
A brief description on the optical path and circuit of the IR system is presented. After analyzing the behavior of the pyroelectric detector detecting instrument response to the radiation, a complex performance parameter automated measurement system is put forward. And the response time is measured by the step response method, which founded the experimental basis for the detecting instrument's correct operation.
A new type of the double layers polycrystal dielectric film in the quartz capillary has been fabricated. The first film is composed of nanoscale germanium dioxide obtained from controlling reaction temperature, gas flow rate and the proportion of reactants, and the second film is metal layer that has high refractive index at infrared region. So the dual-layer thin film has very high reflectivity at the wavelength range of 8-11 .6 µ m. The hollow-core optical fiber with this film on inner wall can transmit over 400 watts of cw carbon dioxide laser power or the pulse carbon dioxide laser with pulse width of 0.1 second and peak-power of 1000 watts, and transmission loss is less than O.6dB/m at 10.6 µ m in transmitting high power. The transmitting laser power fibers can be applied in medical treatment, mechanical process or the relevant scientific research etc.