• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.5 s.96
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• pp.494-500
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• 2005

In this paper, optical noise is reduced by a differential detector with an optical fiber coupler in an optical wireless system. An $1\times2$ optical fiber coupler divides the received optical signal by 2 equally, and connects them to the two photodiodes in a differential detector. The output voltage variation due to the abrupt change of optical noise distribution in space disappears because the two photodiodes effectively detect the optical signal at the same point. The signal to noise ratio in a differential detector with a fiber coupler was 8 dB higher than in a single photodiode with an optical filter.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.179-182
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• 2005

In this paper, optical noise is reduced using a differential detector in an 1.3$\mu$m optical wireless system which is more safe for human eye than 0.8$\mu$m optical wireless systems. The differential detector is composed of a InGaAs photodiode and a Si photodiode. This is a very simple and cost effective method to reduce the noise interference from incandescent lamps.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.891-897
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• 2003

In this paper, a circular orthogonal polarizer is newly fabricated and used in a differential detector to reduce the optical noise in a wireless optical interconnection. The orthogonal polarizer is composed of two semicircular polarizers whose transmission axes are orthogonal each other, The orthogonal polarizer is driven by a motor and matched to the signal polarization in order to reduce the optical noise interference. The noise power was reduced by about 20 dB using a differential detector with the orthogonal polarizer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.822-829
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• 2000

In this paper, we introduce a differential detector that automatically aligns itself to the signal beam in order to prevent the voltage variation that may result from minute misalignment of the light source. In this system, a photodiode-array recognizes the central point of the signal beam, and drives motors that correspond to the x and y axes. The photodiode-array aligns itself to the central point of the signal beam, and eliminates the optical noise effect with differential detectioin method. It is very useful in wireless optical interconnections.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.746-752
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• 2005

In this paper, optical noise effect is reduced by using the loss characteristics of plastic fibers in an optical wireless system. The attenuation coefficient of a plastic fiber for the signal is different from that f3r the noise light, and the length difference between two fibers to the 2PD's behaves like a discriminative element. It is possible to eliminate the optical noise effect and detect only the signal without optical filters. The signal to noise ratio in a differential detector using fibers was 9.7 dB higher than in a single photodiode without optical fiber.