Andrew R. Pirich

Response of germanium-doped fiber Bragg gratings in radiation environments

Fiber Bragg gratings were examined in situ while exposed to gamma-ray and proton environments that emulated or exceeded nominal low earth orbit radiation doses. Radiation and temperature induced changes to the reflected Bragg grating amplitude and spectral characteristics were observed in fiber gratings not formed under hydrogen loading. THe irradiations were performed in situ, while the ambient temperature near the Bragg grating was allowed to vary. Shifts in the reflected spectra from the Bragg gratings were observed and attributed to ionization and thermal effects. During irradiation, the spectral shifts were observed to move to longer wavelengths, saturate at low dose and to decrease exponentially following the cessation of radiation.

Radiation resistance of electro-optic polymer-based modulators

Mach–Zehnder interferometric electro-optic polymer modulators composed of highly nonlinear phenyltetraene bridge-type chromophores within an amorphous polycarbonate host matrix were investigated for their resistance to gamma rays and 25.6 MeV protons. No device failures were observed and the majority of irradiated modulators exhibited decreases in half-wave voltage and optical insertion losses compared to nonirradiated control samples undergoing aging processes. Irradiated device responses were attributed to scission, cross-linking, and free volume processes. The data suggests that strongly poled devices are less likely to de-pole under the influence of ionizing radiation.

Behavior of NLO polymer modulators irradiated by gamma rays

Two second-order nonlinear optical chromophoric materials were investigated for their response to gamma-ray irradiations for doses ranging from approximately 10-104 krad(Si). Thin film polymer modulators composed of a mixture of amorphous polycarbonate and phenyltetraene [APC/CLD-1(CPW-1)] active regions with UV upper and lower UV claddings were investigated for their pre- and post-irradiation behavior. Modulator Vπ insertion loss, and extinction ratio responses were examined, while a blend of salmon deoxyribonucleic acid (DNA)- hexadeCetylTriMethylAmmonium Chloride (CTMA) film samples were studied for their spectral response following irradiations over the spectral range λ=240-2600 nm. Following irradiation ranging from 9.6-104 krad(Si), the DNA/CTMA films exhibited losses in transmissivity over the spectral range λ=882-2600 nm and increased transmissivity over portions of the 240 nm < λ < 882 nm band. Data from the study also suggested that strongly poled APC/CPW-1 modulators operating at λ=1550 nm and exhibiting low Vπ values were less likely to have their half-wave voltages affected by ionizing radiation. The optical insertion losses for the majority of the APC/CPW-1 irradiated mdolators were found to decrease following irradiation. Discussion of the experimental results and mechanisms believed responsible for the post-irradiation behavior and results are presented.

Radiation-resistant polymer-based photonics for space applications

Empirical data regarding the radiation induced responses of Mach Zehnder interferometric electro-optic polymer based modulators (PBMs) operating at 1310 and 1550 nm and broadband InP quantum dot (QD) polymer photodetectors (PPDs) operating into the near infrared (NIR) are reported. Modulators composed of spun-on materials and hybrid electostatically self assembled (ESA) and spun-on NLO materials are examined for changes to their half-wave voltage and insertion losses following a gamma-ray total dose of 163 krad(Si) and irradiation by 25.6 MeV protons at a fluence of ~1011 cm-2. Pre- and post- irradiation responses of ESA grown polymer detectors using InP QDs are examined for photovoltage degradation and aging effects. The data indicates and excellent potential for developing polymer based photonic (PBP) devices with increased radiation resistance suitable for transition to photonic space applications.

Q-switched/cw pulse trains produced by mode-locked fiber laser

A mode-locked erbium-ytterbium fiber laser operating at 1550 nm using multiple quantum well (MQW) saturable absorbers was developed. The laser was constructed in a Fabry-Perot configuration using a fiber Bragg grating as a front reflector and a fiber chirped Bragg grating output as a back reflector of the laser cavity. The laser can either produce Q-switched or CW passively mode-locked pulse trains by simply changing the location of the saturable absorber with respect to a focal plane. The pulse train of laser Q- switching operates at an 85-KHz repetition rate when the position of the absorber is near the focus. Peak power of the Q-switching pulses is about thirty times higher than for the CW mode locking which occurs when the absorber is placed exactly at the focal plane. The CW passively mode-locked pulse trains have a 19-MHz repetition rate with 2.6-mW average output power.

Front Matter: Volume 8057

This PDF file contains the front matter associated with SPIE Proceedings Volume 8057, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Front Matter: Volume 9123

This PDF file contains the front matter associated with SPIE Proceedings Volume 9123 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Implementation of quantum game theory simulations using Python

This paper provides some examples about quantum games simulated in Python’s programming language. The quantum games have been developed with the Sympy Python library, which permits solving quantum problems in a symbolic form. The application of these methods of quantum mechanics to game theory gives us more possibility to achieve results not possible before. To illustrate the results of these methods, in particular, there have been simulated the quantum battle of the sexes, the prisoner’s dilemma and card games. These solutions are able to exceed the classic bottle neck and obtain optimal quantum strategies. In this form, python demonstrated that is possible to do more advanced and complicated quantum games algorithms.

Front Matter: Volume 8749

This PDF file contains the front matter associated with SPIE Proceedings Volume 8749 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Futuristic photonic information systems

It seems like just yesterday that 10 Gb/s (OC-192) transmission was the norm in data rates with slower data rates disappearing! The particular bit-rate jump to 40 Gb/s (OC-768) is not a trivial task. Electronic designers now face serious complexities as they push the technology to the limit. Issues such as chromatic dispersion and polarization mode dispersion are placing more stringent requirements on fiber optics and associated components. The requirement to gather and transfer data at faster and faster rates has spurned an evolution in the thought processes of Photonic engineers. It appears that to handle the ever-increasing bandwidths, Photonic techniques are the way to go! Sophisticated photonic analog-to-digital conversion systems are now being designed at Air Force government laboratories. Only time will tell if these designs can handle the voluminous amounts of data!