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Montréal, Canada

Max J.-J.,Avensys Inc. | O'Reilly S.,ITF Labs
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

We present a robust post-processing technique to extract the polarization dependant frequency (PDF) and Polarization dependant loss (PDL) from stokes measurements of differential phase shift keying (DPSK) demodulators. The proposed method is based on sine-fitting on transmissions. It evaluates PDF and PDL from fitting parameters (phase, amplitude and amplitude offset) through a Müller matrix analysis. © 2011 SPIE.

Zhao Y.,Avensys Inc. | Zhao Y.,MPB Communications Inc. | Zhou C.,Avensys Inc. | Zhou C.,ITF Laboratory Avensys Inc.
Optical Fiber Technology | Year: 2011

A reference grating method for characterizing low-reflectance Bragg gratings in a polarization maintaining (PM) fiber and the corresponding state of polarization (SOP) is presented, and experimentally demonstrated through a fast inline characterization of a PM twin (0.5% + 0.5%) fiber Bragg gratings (FBGs) during the fabrication. The polarization extinction ratio of the pre-set system SOP was determined to be 15.0 dB. The reflectivity measurement for the first grating was carried out while writing the target grating to 1.39%, then in-situ annealing, until after-annealing with a reflectivity of 0.49%. The spectra of the second grating and the combined gratings were characterized by the same way. The combined twin PM FBGs had a bandwidth of 0.515 nm, a center wavelength of 974.304 nm, and a reflectivity of 1.03%. The speed was normally 5 s, and was 3 s without characterizing the system SOP. The reflectivity measurement accuracy was 0.049%. © 2011 Elsevier Inc. All rights reserved.

Zhao Y.,Avensys Inc. | Zhao Y.,MPB Communications Inc. | Hou R.,Avensys Inc. | Zhou C.,Avensys Inc.
Optical Engineering | Year: 2010

A linearly scaling optical apodization method for laser beam power profile modulation is induced. Changing an amplitude mask position between the beam-focusing cylindrical lens and the fiber can linearly scale the vertical apodization profile; this, in turn, enables the optimization of the grating apodization. By using this method, an apodized fiber Bragg grating (FBG) that is designed as an uncooled pump laser diode stabilizer with the specifications of 4.5% reflectivity, 1.6 nm bandwidth, and the side-lobe suppression ratio (SLSR) of 30 dB was UV-imprinted with a tiny Gaussian amplitude mask. Using the same apodization method, a nonchirped-type FBG edge filter was written with a very smooth spectrum. The grating specifications of 0.5-dB attenuation bandwidth of 3.6 nm and 96.5% reflectivity were achieved. The half-spectrum ascending bandwidth in the longer wavelength side is 2.2 nm with 27-dB SLSR. The linearly scaling apodization method is highly beneficial for optimizing the apodization process of UV-writing shorter FBGs with strong apodization. © 2010 Society of Photo-Optical Instrumentation Engineers.

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