The Key Technology Studies Of Ultra-High-Speed Optical Time Division Multiplexing(OTDM) Communications System

With the rapid advances of the commutative multi-media services, the internet services and the broad-band integrated-services-digital-networks (ISDN) in the last ten years, it becomes evident that the communication capability is being increased at exponential speed, so the higher demands are put forward for the transmission velocity and the transmission band-width now. It has become a hotspot in the field of telecommunication research throughout the world, which is the all-optical network communication associated the ultra-high-speed optical-time-division-multiplexing (OTDM) technology with the dense-wave-division-multiplexing (DWDM) technology, in particular, the ultra-high-speed OTDM technology is the first choice for the ultra-high-speed and ultra-large-capability communications system (Tbit/s). The paper is mainly involved in the ultra-high-speed OTDM key technologies, a series of theoretical researches have been done on the ultra-high-speed OTDM communications system in this dissertation. The main contents of the work are as follows: Firstly, the key technologies of the ultra-high-speed OTDM communications system is reviewed, summarized and described at length. Secondly, the basic principles of the mode-locked laser diodes (MLLDs) are described in detail. The momentary characteristics and the threshold-current characteristics of the multi- quantum-well (MQW) external-cavity hybrid MLLDs are given respectively, and the numerical calculations are performed inside country. Moreover, the experimental mode of the MLLDs is optimized at best, and the reasonable theories of MLLDs are provided for the last experimentation. Thirdly, the noise characteristics and the chirp characteristics of the MQW external-cavity hybrid MLLDs (10GHz) are firstly presented at home. By the numerical calculations, the 10GHz MQW hybrid MLLDs are optimized and discussed in test. Finally,the experimental theories of nearly transform-limited pulse, higher repeating rate (10GHz), multi-quantum wells, external -cavity modulation and hybrid mode-locked MLLDs are provided and discussed seriously in the round.In the experimental aspects, first of all, a set of experimental setup based on the MQW external-cavity hybrid MLLDs (10GHz) is firstly put up and tested at home, so we have had a better experimental result in the field at present. Our research team have achieved the ultra-short communication pulse with lesser pulse-width(2.9ps), lesser chirping (～0.43),lesser time jittery (<0.6ps),lesser saturated energy (<1pJ), ultra-high-speed recovery time (8ps), higher repeating rate (10GHz), accurately controlled wavelength (1.5μm), bigger wavelength tuning spectrum scope (35nm), simple structure, higher integration, better stability and long-time working characteristics so on. Secondly, with regard to the MQW external-cavity hybrid MLLDs combined the transform-limited pulse (0.43) with higher repeating rate (10GHz), we have succeeded in fulfilling it in use of our self-made experimental setup. The experimental results are mainly composed of the spontaneous radiation spectrum, wavelength blue-shifted phenomenon, the relations between continuous laser optical power and gain current, mode-locked laser pulse spectrum, higher repeating frequency mode-locked pulse shape, mode-locked pulse-width, RF spectrum of mode-locked pulse, and the calculation of the mode-locked pulse optical power so on. Thirdly, through the MQW hybrid MLLDs (10GHz), the ultra- high-speed OTDM communications system with higher repeating rate (40GHz) is firstly studied inside country. We have realized a set of 40Gb/s ultra-high-speed OTDM communications system only by one 10Gb/s ultra-high-speed MLLDs based on wavelength 1.55μm, which can provide the ultra-short pulse of higher repeating rate (40GHz) and lesser pulse-width (3ps). In our opinions, the experimental results are well in agreement with the anticipatively related principles. All in all, the 40Gb/s ultra-high-speed system is an ideal pulse-generator of the future ultra-high-speed OTDM communications system.The...