Wdm transmitter for optical networks using a loop-back spectrally sliced

Abstract

An apparatus and method pulses a broadband optical source such as an LED, and generates multiple optical wavelength signals channels which are time division multiplexed onto a single optical channel. The multiple optical wavelength signals may subsequently be modulated by low frequency data signals and then transmitted to a receiver as corresponding multiple independent optical wavelength channels over a single optical fiber. Both spectral slicing and time division multiplexing are accomplished by a wavelength channel defining assembly including a wavelength grating router (WGR) and optical delay lines by using the periodic routing characteristics of the WGR. The WGR separates the broadband optical signal appearing at one input port of the WGR into discrete wavelength bands constituting respective pulses defining the optical wavelength channels by spectrally slicing the broadband optical source frequency spectrum with a multiple channel filter. The WGR then routes each of the wavelength signals to corresponding output ports. Optical delay lines then loop-back the separate wavelength signals from the output ports to other WGR input ports determined according to the routing characteristics of the WGR to multiplex the channels onto a single output port, while also inserting the delay to separate the wavelength signals in time.