Effect of Spatial Atomic Oxygen on Polarization Contrast of Polarization-Maintaining Mirror

A method which utilizes a Kerr phase-interrogator to measure the group birefringence dispersion (GBD) of a polarization-maintaining fiber (PMF) is systematically studied in this paper. The differential group delay of two sinusoidally modulated optical signals (SMOSs) polarized along the principal axes of the PMF is measured by a Kerr phase-interrogator, which leads to the group birefringence of the PMF. As the laser wavelength of the SMOSs varies, the group birefringence as a function of the laser wavelength is obtained, and the GBD is calculated as the derivative of the group birefringence with respect to the laser wavelength. The proposed method is experimentally demonstrated by characterizations of a Panda PMF with high GBD and an elliptical core PMF with low GBD, and its performance is analyzed. The proposed method eliminates the impact of the laser coherent length and allows for characterizing the GBD of PMFs that are tens of kilometers long.

Download Full-text

The Effect of Low Earth Orbit Atomic Oxygen Exposure on Phenylphosphine Oxide-Containing Polymers

High Performance Polymers ◽

10.1088/0954-0083/12/1/304 ◽

2000 ◽

Vol 12 (1) ◽

pp. 43-52 ◽

Cited By ~ 30

Author(s):

John W Connell

Keyword(s):

Thin Film ◽

Atomic Oxygen ◽

Low Earth Orbit ◽

Space Environment ◽

Earth Orbit ◽

Cooperative Effort ◽

Flight Experiment ◽

Oxygen Exposure ◽

Atomic Oxygen Exposure ◽

Phenylphosphine Oxide

Thin films of phenylphosphine oxide-containing polymers were exposed to low Earth orbit aboard a space shuttle flight (STS-85) as part of flight experiment designated Evaluation of Space Environment and Effects on Materials (ESEM). This flight experiment was a cooperative effort between the NASA Langley Research Center (LaRC) and the National Space Development Agency of Japan (NASDA). The thin-film samples described herein were part of an atomic oxygen exposure (AOE) experiment and were exposed to primarily atomic oxygen (∼1×1019 atoms cm−2). The thin-film samples consisted of three phosphine oxide-containing polymers (arylene ether, benzimidazole and imide). Based on post-flight analyses using atomic force microscopy, x-ray photo-electron spectroscopy and weight loss data, it was found that the exposure of these materials to atomic oxygen (AO) produces a phosphorus oxide layer on the surface of the samples. Earlier work has shown that this layer provides a barrier towards further attack by AO. Consequently, these materials do not exhibit linear erosion rates which is in contrast with most organic polymers. Qualitatively, the results obtained from these analyses compare favourably with those obtained from samples exposed to AO and/or an oxygen plasma in ground-based exposure experiments. The results of the low Earth orbit AO exposure on these materials will be compared with those of ground-based exposure to AO.

Download Full-text

A Highly Birefringent Photonic Crystal Fiber for Terahertz Spectroscopic Chemical Sensing

Sensors ◽

10.3390/s21051799 ◽

2021 ◽

Vol 21 (5) ◽

pp. 1799

Author(s):

Tianyu Yang ◽

Liang Zhang ◽

Yunjie Shi ◽

Shidi Liu ◽

Yuming Dong

Keyword(s):

Photonic Crystal ◽

Photonic Crystal Fiber ◽

Chemical Sensing ◽

Numerical Aperture ◽

Wide Band ◽

Relative Sensitivity ◽

Chemical Sensitivity ◽

High Birefringence ◽

Crystal Fiber ◽

Polarization Maintaining

A photonic crystal fiber (PCF) with high relative sensitivity was designed and investigated for the detection of chemical analytes in the terahertz (THz) regime. To ease the complexity, an extremely simple cladding employing four struts is adopted, which forms a rectangular shaped core area for filling with analytes. Results of enormous simulations indicate that a minimum 87.8% relative chemical sensitivity with low confinement and effective material absorption losses can be obtained for any kind of analyte, e.g., HCN (1.26), water (1.33), ethanol (1.35), KCN (1.41), or cocaine (1.50), whose refractive index falls in the range of 1.2 to 1.5. Besides, the PCF can also achieve high birefringence (∼0.01), low and flat dispersion, a large effective modal area, and a large numerical aperture within the investigated frequency range from 0.5 to 1.5 THz. We believe that the proposed PCF can be applied to chemical sensing of liquid and THz systems requiring wide-band polarization-maintaining transmission and low attenuation.

Download Full-text