Fibre-based short pulse generation and shaping technology

摘要

The development of the erbium doped fibre amplifier has resulted in tremendous increases in transmission capacity over the past few years with demonstrations of error free data transmission at single channel bit rates as high as 200 Gbit/s using OTDM technology. Soliton transmission arguably offers the greatest potential for exploiting the enormous transmission capacity of EDFA based transmission lines with impressive demonstrations over both transoceanic and terrestrial distances. Further advances should continue to be made with the refinement of advanced soliton control techniques. A key issue when pushing transmission capacity to the limits is the development of stable pulse sources capable of generating pulses of an appropriate form (e.g. shape, duration, repetition rate and wavelength), and of sufficient quality (e.g. transform-limited, low-jitter) so as not to limit the attainable transmission distances. Both semiconductor and fibre based generation schemes are an option, each with relative merits and disadvantages. Semiconductor based pulse schemes, e.g. gain-switched laser diodes, MOW modulators, offer advantages of simplicity, compactness and stability but can suffer limitations regarding the range of output pulse forms attainable, pulse quality and broadband tunability. Conversely, fibre based pulse generation offers high pulse quality, wider operating regimes, e.g. shorter pulse durations, higher powers, novel pulseforms, and broadband tunability but suffers in terms of device compactness and stability. In this paper we review the current state of development df fibre based pulse generation technology for communication applications describing the principal fibre based short pulse generation techniques so far demonstrated. In addition, we discuss the option of using novel fibre componentry, e.g. controllably chirped fibre gratings, dispersion varying fibre, to extend and improve the performance of semiconductor/integrated optics based short pulse sources. Such hybrid systems which exploit both the flexibility of the fibre approach and the stability of semiconductors seem the most likely fibre based sources to find real world application.