Reconfigurable optical transceiver for use with multiple modulation techniques

1 . An optical module for use with multiple optical modulation techniques, the optical module comprising:

a plurality of lasers, each of at least some of the lasers configured to be selectively turned on and turned off depending on a type of modulation to be used, each laser corresponding to a respective wavelength, wherein the plurality of lasers are configurable so that multiple lasers among the plurality of lasers are i) turned on in a first configuration of the optical module and ii) turned off in a second configuration of the optical module;

an optical modulation system comprising a plurality of optical modulators; and

a reconfigurable optical network that is configured to selectively direct light from the plurality of lasers to the optical modulation system differently depending on the type of modulation to be used, wherein the reconfigurable optical network is configurable so that i) light from respective lasers among the multiple lasers are directed to respective modulators in the first configuration, and ii) light from a first laser that is turned on in the second configuration is directed to multiple modulators in the second configuration, and wherein the reconfigurable optical network comprises:

a first variable optical coupler having i) a first input coupled to the first laser, ii) a first output, and iii) a second output,

a second variable optical coupler having i) a first input coupled to the first output of the first variable optical coupler, ii) a first output coupled to an input of a first optical modulator among the plurality of optical modulators, and iii) a second output coupled to an input of a second optical modulator among the plurality of optical modulators, and

a third variable optical coupler having i) a first input coupled to the second output of the first variable optical coupler, ii) a first output coupled to an input of a third optical modulator among the plurality of optical modulators, and iii) a second output coupled to an input of a fourth optical modulator among the plurality of optical modulators.

2 . The optical module of claim 1 , further comprising:

a polarization beam rotator combiner (PRBC) configured to combine light from the plurality of optical modulators to generate an optical transmit signal when any of multiple ones of the optical modulation techniques are being used.

3 . The optical module of claim 1 , wherein:

the first variable optical coupler includes a second input coupled to a second laser among the plurality of lasers;

the second variable optical coupler includes a second input coupled to a third laser among the plurality of lasers; and

a third variable optical coupler includes a second input coupled to a fourth laser among the plurality of lasers.

4 . The optical module of claim 2 , wherein:

the optical modulation system is configurable so that the plurality of optical modulators are i) configured to modulate according to a first modulation technique when the optical modulation system is in a first configuration, and ii) configured to modulate according to a second modulation technique when the optical modulation system is in a second configuration.

5 . An optical transceiver comprising the optical module of claim 2 , the optical transceiver further comprising:

a controller configured to generate control signals to selectively turn on and turn off the at least some of the lasers depending on the type of modulation to be used; and

a baseband processor configured to

receive data that is to be transmitted, and

generate, based on the data that is to be transmitted, modulation signals for controlling the plurality of optical modulators.

6 . The optical transceiver of claim 5 , wherein the baseband processor includes the controller.

7 . The optical module of claim 2 , wherein the reconfigurable optical network is a first reconfigurable optical network, and wherein the optical module further comprises:

optical-to-electrical conversion circuitry that includes a plurality of photodiodes coupled to a plurality of transimpedance amplifiers (TIAs), the plurality of photodiodes including multiple-input photodiodes, each multiple-input photodiode including a first side and a second side that is opposite the first side;

an optical processor that is configured to optically process one or more optical signals corresponding to coherent modulation, the optical processor being coupled to the plurality of photodiodes, including multiple outputs of the optical processor coupled to the respective first sides of the multiple-input photodiodes; and

a second reconfigurable optical network that is configured to i) in a first configuration corresponding to a first modulation technique, direct optical signals corresponding to light received via an optical medium to the respective second sides of the multiple-input photodiodes so that the light bypasses the optical processor, and ii) in a second configuration corresponding to a second modulation technique, direct one or more optical signals corresponding to light received via the optical medium to one or more inputs of the optical processor.

8 . The optical module of claim 7 , wherein the second reconfigurable optical network comprises:

an optical demultiplexer having a plurality of outputs optically coupled to the respective second sides of the multiple-input photodiodes.

9 . The optical module of claim 8 , wherein the second reconfigurable optical network further comprises:

an optical switch having i) an input coupled to one of the outputs of the optical demultiplexer, ii) a first output coupled to a second side of one of the multiple-input photodiodes, and iii) a second output coupled to one or more inputs of the optical processor, wherein i) in the first configuration corresponding to the first modulation technique, the optical switch directs an optical signal from the one output of the optical demultiplexer to the second sides of the one multiple-input photodiode, and ii) in the second configuration corresponding to the second modulation technique the optical switch directs the optical signal from the one output of the optical demultiplexer to the one or more inputs of the optical processor.

10 . The optical module of claim 8 , wherein the second reconfigurable optical network further comprises:

a polarization beam splitter coupled between the second output of the optical switch and the optical processor.

11 . An optical transceiver that includes the optical module of claim 7 , further comprising:

a plurality of analog-to-digital converters (ADCs) coupled to the plurality of TIAs, the plurality of ADCs to convert analog outputs of the TIAs to respective digital domain signals.

12 . The optical transceiver of claim 11 , further comprising:

a baseband processor coupled to the plurality of ADCs, the baseband processor configured to recover information bits from the digital domain signals.

13 . A method of controlling a reconfigurable optical module for transmitting information via an optical medium, the method comprising:

determining, at a controller, a type of modulation that is to be used to transmit the information via the optical medium, the type of modulation being determined from a plurality of different types of optical modulation techniques, including at least a first type and a second type;

controlling, by the controller, a plurality of lasers of the reconfigurable optical module to one of i) turn on or ii) turn off at least some of lasers among the plurality of lasers depending on the type of modulation to be used, each laser corresponding to a respective wavelength; and

controlling, by the controller, a reconfigurable optical network of the reconfigurable optical module to selectively direct light from the plurality of lasers to an optical modulation system of the reconfigurable optical module differently depending on the type of modulation to be used, wherein controlling the reconfigurable optical network comprises:

controlling a first variable optical coupler having a first input coupled to the first laser, so that light from the first laser i) is directed only to a first output of the first variable optical coupler in the first configuration, and iii) is directed to the first output of the first variable optical coupler and a second output of the first variable optical coupler in the second configuration,

controlling a second variable optical coupler having a first input coupled to the first output of the first variable optical coupler so that light from the first laser i) is directed, in the first configuration, only to a first output of the second variable optical coupler that is coupled to a first modulator among the plurality of optical modulators, and iii) is directed, in the second configuration, to the first output of the first variable optical coupler and a second output of the second variable optical coupler that is coupled to a second modulator among the plurality of optical modulators, and

controlling a third variable optical coupler having a first input coupled to the second output of the first variable optical coupler so that light received via the first input of the third variable optical coupler i) is directed, in the first configuration, only to a first output of the third variable optical coupler that is coupled to a third modulator among the plurality of optical modulators, and iii) is directed, in the second configuration, to the first output of the first variable optical coupler and a second output of the second variable optical coupler that is coupled to a fourth modulator among the plurality of optical modulators.

14 . The method of controlling the reconfigurable optical module of claim 13 , further comprising:

combining, using a polarization beam rotator combiner (PRBC), light from a plurality of optical modulators of the optical modulation system to generate an optical transmit signal when any of multiple ones of the different types of optical modulation techniques are being used.

15 . The method of controlling the reconfigurable optical module of claim 13 , wherein controlling the reconfigurable optical network further comprises:

controlling the first variable optical coupler so that light from a second laser coupled to a second input of the first variable optical coupler is directed only to the second output of the first variable optical coupler in the first configuration;

controlling the second variable optical coupler so that light from a third laser coupled to a second input of the second variable optical coupler is directed, in the first configuration, only to the second output of the second variable optical coupler; and

controlling the third variable optical coupler so that light from a fourth laser coupled to a second input of the third variable optical coupler is directed, in the first configuration, only to the second output of the third variable optical coupler.

16 . The method of controlling the reconfigurable optical module of claim 14 , further comprising:

configuring the optical modulation system so that the plurality of optical modulators of the optical modulation system are i) configured to modulate according to the first modulation technique when the optical modulation system is in a first configuration, and ii) configured to modulate according to the second modulation technique when the optical modulation system is in a second configuration.

17 . A method of controlling an optical transceiver comprising the method of claim 14 , the method of controlling the optical transceiver further comprising:

receiving, at a baseband processor of the transceiver, data that is to be transmitted via the optical medium;

generating, at the baseband processor, modulation signals for controlling the plurality of optical modulators based on the data received at the baseband processor; and

providing the modulation signals to the optical module to control the plurality of optical modulators.

18 . The method of operating the reconfigurable optical module of claim 14 , wherein the reconfigurable optical network is a first reconfigurable optical network, wherein the reconfigurable optical module further includes optical-to-electrical conversion circuitry that includes a plurality of photodiodes coupled to a plurality of transimpedance amplifiers (TIAs), the plurality of photodiodes including multiple-input photodiodes, each multiple-input photodiode including a first side and a second side that is opposite the first side, the optical module further including an optical processor that is configured to optically process one or more optical signals corresponding to coherent modulation, the optical processor being coupled to the plurality of photodiodes, including multiple outputs of the optical processor coupled to the respective first sides of the multiple-input photodiodes, the method further comprising:

determining, at the controller, a type of modulation for which the reconfigurable optical module is to process optical signals received via the optical medium, the type of modulation being determined from the plurality of different types of optical modulation techniques, including at least a first type and a second type; and

controlling, by a controller, a second reconfigurable optical network of the reconfigurable optical module to selectively i) in a first configuration corresponding to a first modulation technique, direct optical signals corresponding to light received via the optical medium to respective first sides of the multiple-input photodiodes so that the light bypasses the optical processor, and ii) in a second configuration corresponding to a second modulation technique, direct one or more optical signals corresponding to light received via the optical medium to one or more inputs of the optical processor.

19 . The method of operating the reconfigurable optical module of claim 18 , further comprising, in the first configuration:

demultiplexing, with an optical demultiplexer, light at respective wavelengths from an optical signal corresponding to light received via the optical medium; and

providing respective optical signals output by the optical demultiplexer the respective second sides of the multiple-input photodiodes.

20 . The method of operating the reconfigurable optical module of claim 19 , wherein the second reconfigurable optical network includes an optical switch having i) an input coupled to one of the outputs of the optical demultiplexer, ii) a first output coupled to a second side of one of the multiple-input photodiodes, and iii) a second output coupled to one or more inputs of the optical processor, and wherein controlling the second reconfigurable optical network comprises:

controlling, by the controller, the optical switch so that i) in the first configuration corresponding to the first modulation technique, the optical switch directs an optical signal from the one output of the optical demultiplexer to the second sides of the one multiple-input photodiode, and ii) in the second configuration corresponding to the second modulation technique the optical switch directs the optical signal from the one output of the optical demultiplexer to the one or more inputs of the optical processor.

21 . The method of operating the reconfigurable optical module of claim 20 , further comprises, the second configuration:

splitting, by a polarization beam splitter, an output signal from the second output of the optical switch into a first polarized signal and a second polarized signal; and

providing the first polarized signal and the second polarized signal to inputs of the optical processor.

22 . A method of operating an optical transceiver including the method of claim 18 , the method further comprising:

converting, by a plurality of analog-to-digital converters (ADCs), analog outputs of the TIAs to respective digital domain signals.

23 . The method of operating the optical transceiver of claim 22 , further comprising:

recovering, by a baseband processor, information bits from the digital domain signals.