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A new sampling calorimeter using very thin scintillators and the multi-pixel photon counter (MPPC) has been proposed to produce better position resolution for the international linear collider (ILC) experiment. As part of this R&D study, small plastic scintillators of different sizes, thickness and wrapping reflectors are systematically studied. The scintillation light due to beta rays from a collimated 90Sr source are collected from the scintillator by wavelength-shifting (WLS) fiber and converted into electrical signals at the PMT. The wrapped scintillator that gives the best light yield is determined by comparing the measured pulse height of each 10 x 40 x 2 mm strip scintillator covered with 3M reflective mirror film, teflon, white paint, black tape, gold, aluminum and white paint+teflon. The pulse height dependence on position, length and thickness of the 3M reflective mirror film and teflon wrapped scintillators are measured. Results show that the 3M radiant mirror film-wrapped scintillator has the greatest light yield with an average of 9.2 photoelectrons. It is observed that light yield slightly increases with scintillator length, but increases to about 100% when WLS fiber diameter is increased from 1.0 mm to 1.6 mm. The position dependence measurement along the strip scintillator showed the uniformity of light transmission from the sensor to the PMT. A dip across the strip is observed which is 40% of the maximum pulse height. The block type scintillator pulse height, on the other hand, is found to be almost proportional to scintillator thickness. [ABSTRACT FROM AUTHOR]

We simulated the differential modal gain (DMG) property of WDM amplification characteristics for a ring-core erbium-doped fibre (RC-EDF) to clarify the possibility of an RC-EDF being used as a three- to five-signal LP-mode amplification medium. The authors defined two parameters, DMGYY-XX and WDGXX. The former and the latter are the difference between the gains of the LPXX mode and the LPYY mode at the shortest wavelength, and the gains of the LPXX mode at the shortest and longest wavelengths of WDM signal channel, respectively. XX and YY indicate the signal LP mode number. The authors present contour diagrams of the maximum DMGYY-XX and maximum WDGXX on the allowable three- to five-signal LP-mode areas of the RC-EDF. They confirm that it is possible to realise the amplification with a maximum DMGYY-XX of ≤2 dB, ≤1 dB, and about 2 dB for the 3, 4, and 5-LP modes and a maximum WDGXX of ≤ 1 dB for the three- to five-LP mode. The authors found that it is possible to realise an amplifier for 3-5 LP modes that operate with a relatively low DMG by using RC-EDF. [ABSTRACT FROM AUTHOR]

The first light source with a broadband spectrum in the 1800 nm wavelength region has been developed by employing a cascade configuration with a 1.65 μm band super luminescent diode and a Tm3+-doped fibre amplification unit. The achieved bandwidth where the intensity exceeded -20 dBm/nm was 247 nm (from 1611 to 1858 nm) with a low ripple, whose peak-to-peak value was <0.15 dB. [ABSTRACT FROM AUTHOR]

An inter-core crosstalk measurement method in a multi-core erbiumdoped fibre amplifier that uses a single-wavelength signal with multiple intensity tones is investigated. Its feasibility is confirmed and the output signal power dependence of the crosstalk values for the same signal gains between cores is successfully characterized. [ABSTRACT FROM AUTHOR]

The first ASE light source with a flat and broadband ASE spectrum in the 1800 nm wavelength region has been developed by combining a Tm3+-Tb3+-doped fibre and a Tm3+-doped fibre. The achieved bandwidth where the ASE intensity exceeded -20 dBm/nm was 162 nm (from 1690 to 1852 nm). [ABSTRACT FROM AUTHOR]