A new ion energy analyzer with high angular resolution (⩽3×10−4 sr) is described. It consists of a microchannel plate followed by a retarding-grid type analyzer. The microchannel plate is not used for charge multiplication but as a geometric filter with narrow angular passband (ϑ≃0.6°) yet high transparency (T≃60%). The energy analyzer is used to measure the true velocity space distribution of low-energy ion beams (Eb = 10–100 eV) in a double plasma device. Its superior performance over the conventional gridded energy analyzer is demonstrated. Applications to the study of beam wakes are shown.

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. SPONSOR/MONITOR'S ACRONYM(S) SPONSORING/MONITORING AGENCY REPORT NUMBER AFRL-RY-RS-TP-2008-8 DISTRIBUTION AVAILABILITY STATEMENTApproved for public release; distribution unlimited. PA# AFRL WS 07-0387 SUPPLEMENTARY NOTESPaper published in Proc. of SPIE Vol 6975, 69750N. This material is declared a work of the U. S. Government and is not subject to copyright protection in the United States. ABSTRACTAn electro-absorption modulator (EAM) is designed to optimize dynamic range performance over 20 GHz bandwidth. The single stripe waveguide enables an extremely compact and integrated package to be fabricated with single mode fiber pigtails. The transfer function's shape permits suppression of higher order intermodulation products, yielding a spur-free dynamic range exceeding that of Mach-Zehnder designs. A dilute optical core diverts energy flow from absorbing layers into a low loss waveguide; the 20 dBm optical power tolerance is significantly higher than that o commercially available electro-absorption devices. The tunable performance over 20GHz is characterized and applications are discussed. New approaches to the broadband impedance matching requirements are calculated and the impact on system performance is assessed. SUBJECT TERMS

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Service, Directorate SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)AFRL/RYDP 25 Electronics Pkwy Rome NY 13441-4505 SPONSOR/MONITOR'S ACRONYM(S) SPONSORING/MONITORING AGENCY REPORT NUMBER AFRL-RY-RS-TP-2008-7 DISTRIBUTION AVAILABILITY STATEMENTApproved for public release; distribution unlimited. PA# AFRL WS 07-0388 SUPPLEMENTARY NOTESPaper published in Proc. of SPIE Vol 6975, 69750O. This material is declared a work of the U. S. Government and is not subject to copyright protection in the United States. ABSTRACTExternally coupled electro-absorption modulators (EAM) are commonly used in order to transmit Radio-Frequency (RF) signals on optical fibers. Recently an alternative device design with diluted waveguide structures has been developed. Bench tests show benefits of lower propagation loss, higher power handling (100 mW), and higher normalized slope efficiency. This paper addresses the specific issues involved in packaging the diluted waveguide EAM devices. An evaluation of the device requirements was done relative to the standard processes. Bench tests were performed in order to characterize the optical coupling of the EAM. The photo current maximum was offset from the optical power output maximum. The transmissions vs bias voltage curves were measured, and an XY scanner was used to record the mode field of the light exiting from the EAM waveguide in each position. The Beam Propagation Method was used to simulate the mode field and the coupling efficiency. A design including mechanical, optical and RF elements was developed. A Newport Laser Welding system was utilized for fiber placement and fixation. This paper addresses the specific issues involved in packaging the diluted waveguide EAM devices. An evaluation of the device requirements was done relative to the standard processes. Bench tests were performed in order to characterize the optical coupling of the EAM. The photo current maximum was offset from the optical power output maximum. The transmissions vs. bias voltage curves were measured, and an XY scanner was used to record the mode field of the light exiting from the EAM waveguide in each position. The Beam Propagation Method was used to simulate the mode field and the coupling efficiency. Based on the bench tests and simulation results, a design including mechanical, optical and RF elements was developed. A Newport Laser Welding system was utilized for fiber placement and fixation. The laser welding techniques were customized in order to meet the needs of the EAM package design. SUBJECT TERMS