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All-optical Shaping of Ultra-short OTDM Pulses by Using Semiconductor Optical Amplifiers

IP.com Disclosure Number: IPCOM000124587D
Original Publication Date: 2005-May-20
Included in the Prior Art Database: 2005-May-20
Document File: 2 page(s) / 30K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

In an OTDM (Optical Time Division Multiplexed) system, at each output of the optical demultiplexer, an evident difficulty is given by the necessity to make an accurate sampling of very short optical pulses (typically of the order of picoseconds) after the electro-optic conversion stage at the optical receiver. A new technique is proposed, based on a properly shaping of picoseconds OTDM pulses, which allows a simple and robust sampling process in the electro-optic conversion stage, just by means of one active optical component (a Semiconductor Optical Amplifier SOA). The Two Photon Absorption (TPA) and the fast saturation gain dynamics in SOAs can be used for getting an attractive pulse optical shaping. Because of its short time constant (about 70fs), the TPA induces a strong photon absorption in correspondence of the pulse leading edge. On the other hand, the optical gain, owing to the fast dynamics of the SHB (Spectral Hole-Burning) (50fs) and CH (Carrier Heating) (700fs), rapidly increases the photon density, so that the saturation level is reached before the pulse peak value occurs. The TPA and the saturation gain dynamics contributions act locally on the pulse during the propagation in the SOA, then varying the temporal intensity distribution, which can be properly modeled by correctly choosing the optical gain and the optical input field energy. This attractive SOA feature is shown in Fig.1.

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All-optical Shaping of Ultra-short OTDM Pulses by Using Semiconductor Optical Amplifiers

Idea: Dr. Claudio Crognale, IT-L'Aquila; Dr. Stefano Caputo, IT-L'Aquila

In an OTDM (Optical Time Division Multiplexed) system, at each output of the optical demultiplexer, an evident difficulty is given by the necessity to make an accurate sampling of very short optical pulses (typically of the order of picoseconds) after the electro-optic conversion stage at the optical receiver.

A new technique is proposed, based on a properly shaping of picoseconds OTDM pulses, which allows a simple and robust sampling process in the electro-optic conversion stage, just by means of one active optical component (a Semiconductor Optical Amplifier SOA). The Two Photon Absorption (TPA) and the fast saturation gain dynamics in SOAs can be used for getting an attractive pulse optical shaping. Because of its short time constant (about 70fs), the TPA induces a strong photon absorption in correspondence of the pulse leading edge. On the other hand, the optical gain, owing to the fast dynamics of the SHB (Spectral Hole-Burning) (50fs) and CH (Carrier Heating) (700fs), rapidly increases the photon density, so that the saturation level is reached before the pulse peak value occurs. The TPA and the saturation gain dynamics contributions act locally on the pulse during the propagation in the SOA, then varying the temporal intensity distribution, which can be properly modeled by correctly choosing the optical gain and the optical input field energy. This attractive SOA feature is shown in Fig.1.

In this figure, the output pulses obtained for a 31pJ, 1ps FWHM (Full-Width at Half-Maximum) Gaussian input pulse by varying the SOA optical gain are shown. It emerges that, by changing the SOA gain and the input pulse energy, it is possible to get, at the SOA output, optical pulses with a sharp leading edge and a flat peak level, that kee...