Abstract

Recent achievements in optical amplifiers revitalize the practicality of wavelength-division-multiplexed (WDM) systems. However, WDM systems require a multiple number of transmitter lasers operating at different wavelengths. Thus WDM transmitter lasers should be wavelength selected for each channel and should be controlled to operate at a specific wavelength to the end of system’s lifetime. This process would increase cost and complexity. There have been a few attempts to overcome this problem by using spectrum-sliced broadband light sources, such as 1.3-μm light-emitting diodes (LEDs) with grating-based demultiplexers.^1,2 In this paper, we propose the use of broadband light as a multichannel WDM light source. Our approach is based on the following: (1) it is now possible to obtain strong amplified spontaneous emission (ASE) in excess of 40 mW within the single-mode fiber from an erbium-doped fiber amplifier¹ (EDFA), and (2) highly efficient and easy optical multiplexing is possible with the recently developed integrated-optic WDM multiplexers.^{4 5} Figure 1 shows the schematic diagram of the proposed WDM light source. The broadband ASE light is efficiently split into many WDM channels, modulated individually, and multiplexed back into a single-mode fiber. The (de)multiplexers and modulators could be fabricated monolithically on InP substrates.⁵ Thus this simple arrangement with an EDFA (requiring only one pump laser) can provide light sources for many WDM channels.

© 1994 Optical Society of America