be quite nominal in the embodiment depicted approximately u2212 10 dbm thus signal pre amplification concerns are diminished or avoided the output power of the clock signal in this embodiment is on the order of 0 dbm the laser wavelength of the all optical clock signal is a function of the wavelength amplification spectrum of the second stage soas with suitably designed soas the standard carrier frequencies used in optical networks all fall within the soa amplification spectrum this wavelength can be anywhere in the amplification window of the soas in the second stage 160 soa mzi circuit thus as examples for the c band of optical transmission a wavelength such as 1550 nm may be chosen and for the l band of optical transmission a wavelength such as 1585 nm may be chosen in a preferred embodiment multimode interference mmi couplers with a 50 50 splitting ratio commonly known as 3 db couplers make up the couplers of the first stage 102 and 103 respectively as well as the couplers of the second stage 120 and 125 respectively 0029 fig2 and 2a show the second stage clock recovery circuit in isolation the input 200 to this stage at the top left of the figure is the amplified rz or prz signal output from the first stage the stage comprises a.