Communications network optical apparatus (100, 150, 200, 250, 800, 850, 900, 950, 1000, 1050) comprising: an optical module comprising: optical modulators arranged to modulate optical signals; internal lasers arranged to generate internal optical signals to be modulated by the optical modulators; an input port arranged to receive an external optical signal from an external laser; optical routing devices (128, 400, 500, 600, 710) arranged to route internal optical signals from internal lasers to optical modulators and to route an external optical signal from the input port to at least one of the optical modulators; and a temperature sensor arranged to sense a temperature of the internal lasers and to generate a temperature reporting signal; and a controller (140, 1040) comprising processing circuitry and memory containing instructions executable by said processing circuitry whereby said controller is operative to: receive the temperature reporting signal; determine that a thermal protection condition exists based on the temperature of the internal lasers; and in response to the determining, generate control signals (146, 148, 1046) configured to cause the external optical signal to be provided to at least one optical modulator and to cause an operating power of at least one respective internal laser to be reduced. an optical module comprising: optical modulators arranged to modulate optical signals; internal lasers arranged to generate internal optical signals to be modulated by the optical modulators; an input port arranged to receive an external optical signal from an external laser; optical routing devices (128, 400, 500, 600, 710) arranged to route internal optical signals from internal lasers to optical modulators and to route an external optical signal from the input port to at least one of the optical modulators; and a temperature sensor arranged to sense a temperature of the internal lasers and to generate a temperature reporting signal; and optical modulators arranged to modulate optical signals; internal lasers arranged to generate internal optical signals to be modulated by the optical modulators; an input port arranged to receive an external optical signal from an external laser; optical routing devices (128, 400, 500, 600, 710) arranged to route internal optical signals from internal lasers to optical modulators and to route an external optical signal from the input port to at least one of the optical modulators; and a temperature sensor arranged to sense a temperature of the internal lasers and to generate a temperature reporting signal; and a controller (140, 1040) comprising processing circuitry and memory containing instructions executable by said processing circuitry whereby said controller is operative to: receive the temperature reporting signal; determine that a thermal protection condition exists based on the temperature of the internal lasers; and in response to the determining, generate control signals (146, 148, 1046) configured to cause the external optical signal to be provided to at least one optical modulator and to cause an operating power of at least one respective internal laser to be reduced. receive the temperature reporting signal; determine that a thermal protection condition exists based on the temperature of the internal lasers; and in response to the determining, generate control signals (146, 148, 1046) configured to cause the external optical signal to be provided to at least one optical modulator and to cause an operating power of at least one respective internal laser to be reduced.