Broadband arbitrary wavelength multichannel laser source

Abstract

A multi-channel laser source, including: a bus waveguide coupled, at an output end of the bus waveguide, to an output of the multi-channel laser source; a first semiconductor optical amplifier; a first back mirror; a first wavelength-dependent coupler, having a first resonant wavelength, on the bus waveguide; a second semiconductor optical amplifier; a second back mirror; and a second wavelength-dependent coupler, on the bus waveguide, having a second resonant wavelength, different from the first resonant wavelength. In some embodiments the first semiconductor optical amplifier is coupled to the bus waveguide by the first wavelength-dependent coupler, which is nearer to the output end of the bus waveguide than the second wavelength-dependent coupler, the second semiconductor optical amplifier is coupled to the bus waveguide by the second wavelength-dependent coupler, and the first wavelength-dependent coupler is configured to transmit light, at the second resonant wavelength, along the bus waveguide.

What is claimed is: 
     
         1 . A multi-channel laser source, comprising:
 a bus waveguide coupled, at an output end of the bus waveguide, to an output of the multi-channel laser source;   a first semiconductor optical amplifier;   a first back mirror;   a first wavelength-dependent coupler having a first resonant wavelength;   a second semiconductor optical amplifier;   a second back mirror; and   a second wavelength-dependent coupler having a second resonant wavelength, different from the first resonant wavelength;   the first semiconductor optical amplifier comprising:
 a first end coupled to the first back mirror, and 
 a second end, 
   the first wavelength-dependent coupler comprising:
 a channel port connected to the second end of the first semiconductor optical amplifier; 
 a bus output connected to a first portion of the bus waveguide; and 
 a bus input, connected to a second portion of the bus waveguide more distant from the output end of the bus waveguide than the first portion of the bus waveguide; 
   the second semiconductor optical amplifier being coupled to the bus waveguide through the second wavelength-dependent coupler,   the first wavelength-dependent coupler being nearer to the output end of the bus waveguide than the second wavelength-dependent coupler,   the first wavelength-dependent coupler being configured to transmit light, at the second resonant wavelength, from the bus input of the first wavelength-dependent coupler to the bus output of the first wavelength-dependent coupler.   
     
     
         2 . The multi-channel laser source of  claim 1 , further comprising an output coupler at the output end of the bus waveguide, wherein the first wavelength-dependent coupler is configured to transmit light at the first resonant wavelength from the channel port of the first wavelength-dependent coupler to the bus output of the first wavelength-dependent coupler. 
     
     
         3 . The multi-channel laser source of  claim 1 , wherein the first wavelength-dependent coupler is configured to reflect a first portion of light received at the first resonant wavelength at the channel port of the first wavelength-dependent coupler, and to transmit, to the bus output of the first wavelength-dependent coupler, a second portion of light received at the first resonant wavelength at the channel port of the first wavelength-dependent coupler. 
     
     
         4 . The multi-channel laser source of  claim 3 , wherein the first portion is at least 10% of the light received, and the second portion is at least 40% of the light received. 
     
     
         5 . The multi-channel laser source of  claim 1 , wherein the first wavelength-dependent coupler is configured to transmit, to a fourth port of the first wavelength-dependent coupler, light received at the channel port at the second resonant wavelength. 
     
     
         6 . The multi-channel laser source of  claim 5 , wherein the fourth port of the first wavelength-dependent coupler is connected to an optical absorber. 
     
     
         7 . The multi-channel laser source of  claim 1 , wherein the first back mirror and the first semiconductor optical amplifier are configured as a reflective semiconductor optical amplifier. 
     
     
         8 . The multi-channel laser source of  claim 1 , wherein the first wavelength-dependent coupler comprises a first ring resonator. 
     
     
         9 . The multi-channel laser source of  claim 8 , wherein the first wavelength-dependent coupler further comprises a second ring resonator, the first ring resonator and the second ring resonator being configured to operate as a vernier ring resonator filter. 
     
     
         10 . The multi-channel laser source of  claim 1 , wherein the first wavelength-dependent coupler comprises a grating assisted co-directional coupler. 
     
     
         11 . The multi-channel laser source of  claim 10 , wherein the first wavelength-dependent coupler further comprises a distributed Bragg reflector connected in cascade with the grating assisted co-directional coupler. 
     
     
         12 . The multi-channel laser source of  claim 1 , wherein the first wavelength-dependent coupler comprises a wavelength actuator for adjusting the first resonant wavelength. 
     
     
         13 . The multi-channel laser source of  claim 1 , further comprising a phase shifter between the first back mirror and the first wavelength-dependent coupler. 
     
     
         14 . The multi-channel laser source of  claim 1 , further comprising an amplitude modulator between the first back mirror and the first wavelength-dependent coupler. 
     
     
         15 . The multi-channel laser source of  claim 1 , wherein the first semiconductor optical amplifier is the same semiconductor optical amplifier as the second semiconductor optical amplifier. 
     
     
         16 . The multi-channel laser source of  claim 1 , wherein the first semiconductor optical amplifier comprises a first waveguide in a first semiconductor chip and the second semiconductor optical amplifier comprises a second waveguide in the first semiconductor chip. 
     
     
         17 . The multi-channel laser source of  claim 1 , wherein the first semiconductor optical amplifier comprises a waveguide in a first semiconductor chip, and the second semiconductor optical amplifier comprises a waveguide in a second semiconductor chip, different from the first semiconductor chip. 
     
     
         18 . The multi-channel laser source of  claim 1 , further comprising:
 a wavelength sensor configured to receive a portion of, and to sense a wavelength of, light emitted by the first semiconductor optical amplifier; and   a control system configured:
 to receive a wavelength sensing signal from the wavelength sensor, 
 to calculate a difference between the wavelength sensing signal and a wavelength setpoint, and 
 to apply a wavelength correction signal to a wavelength actuator, to reduce the difference between the wavelength sensing signal and the wavelength setpoint. 
   
     
     
         19 . The multi-channel laser source of  claim 18 , further comprising a phase shifter between the first back mirror and the first wavelength-dependent coupler, wherein the wavelength actuator comprises the phase shifter. 
     
     
         20 . The multi-channel laser source of  claim 18 , wherein the first wavelength-dependent coupler comprises a coupler wavelength actuator for adjusting the first resonant wavelength, wherein the wavelength actuator comprises the coupler wavelength actuator. 
     
     
         21 . The multi-channel laser source of  claim 18 , wherein the wavelength sensor is configured to receive light from a fourth port of the first wavelength-dependent coupler. 
     
     
         22 . The multi-channel laser source of  claim 18 , wherein the wavelength sensor comprises a Mach-Zehnder interferometer having a first arm and a second arm, longer than the first arm, and a temperature control system configured to control the temperature of a portion of the second arm. 
     
     
         23 . The multi-channel laser source of  claim 18 , wherein:
 the first semiconductor optical amplifier comprises a waveguide in a first semiconductor chip; and   the wavelength sensor comprises a photodiode, the photodiode being in the first semiconductor chip.   
     
     
         24 . A multiplexed multi-channel laser source comprising:
 a first multi-channel laser source according to  claim 1 ,   a second first multi-channel laser source according to  claim 1 , and   a multiplexer,   the multiplexer comprising:
 a first input, 
 a second input, and 
 an output, 
   the multiplexer being configured:
 to transmit light from first input to the output, and 
 to transmit light from second input to the output.