Multiple stage Bragg gratings in multiplexing applications

An optical apparatus comprising:

• a plurality of transmitters;
• and
• a multiplexer comprising:
• a first Bragg grating having a first input port coupled with a first transmitter of the plurality of transmitters, a first add port coupled with a second transmitter of the plurality of transmitters, and a first output port configured to output a first optical signal comprising a first two wavelengths received from the first input port and from the first add port;
• a second Bragg grating having a second input port coupled with a third transmitter of the plurality of transmitters, a second add port coupled with a fourth transmitter of the plurality of transmitters, and a second output port configured to output a second optical signal comprising a second two wavelengths received from the second input port and from the second add port;
• a third Bragg grating coupled with the second output port, the third Bragg prating having a third output port configured to output a third optical signal comprising the second two wavelengths from the second optical signal, the third Bragg grating having a third add port coupled with an optical absorber configured to mitigate reflections of wavelengths in the second optical signal other than the second two wavelengths;
• and
• a fourth Bragg grating having a third input port configured to receive the first two wavelengths from the first optical signal, a fourth add port configured to receive the second two wavelengths from the third optical signal, and a fourth output port configured to output a fourth optical signal comprising the first two wavelengths and the second two wavelengths.

An optical apparatus comprising:

• a plurality of receivers;
• and
• a demultiplexer comprising:
• a first Bragg grating having a first input port configured to receive an optical signal, a first drop port configured to transmit a first wavelength and a second wavelength of the optical signal, and a first output port configured to transmit a third wavelength and a fourth wavelength of the optical signal;
• a second Bragg grating having a second input port coupled with the first drop port, a second drop port configured to transmit the first wavelength and the second wavelength, and a second output port coupled with an optical absorber configured to mitigate reflections of the first wavelength and the second wavelength exiting the second output port;
• and
• a third Bragg grating having a third input port configured to receive the first wavelength and the second wavelength from the second drop port, a third drop port configured to transmit the first wavelength to a first receiver of the plurality of receivers, and a third output port configured to transmit the second wavelength to a second receiver of the plurality of receivers;
• and
• a fourth Bragg grating having a fourth input port coupled with the first output port, a fourth drop port configured to transmit the third wavelength to a third receiver of the plurality of receivers, and a fourth output port configured to transmit the fourth wavelength to a fourth receiver of the plurality of receivers.