An apparatus comprising: an uncooled laser (105, 157, 205, 305); a splitter (110, 150, 215, 315) coupled to the laser (105, 157, 205, 305); a first wavelength component (117, 143, 215, 330) coupled to the splitter (110, 150, 215, 315), configured to pass a signal from the splitter (110, 150, 215, 315) to a local oscillator, LO, port (125, 137, 245, 345) and pass a signal from the LO port (125, 137, 245, 345) to a receiver; the LO port (125, 137, 245, 345) coupled to the first wavelength component (117, 143, 215, 330); a modulator (113, 153, 220, 320) coupled to the splitter (110, 150, 215, 315); a second wavelength component (120, 145, 235, 335) coupled to the modulator (113, 153, 220, 320), configured to pass a signal from the modulator (113, 153, 220, 320) to a signal port (127, 140, 250,350) and pass a signal from the signal port (127, 140, 250, 350) to the receiver; and the signal port (127, 140, 250, 350) coupled to the second wavelength component (120, 145, 235, 335), wherein the LO port (125, 137, 245, 345) is configured to: couple to a first duplex fiber which may simultaneously communicate in both the downstream and the upstream direction; and transmit a first LO optical signal to the first duplex fiber; and the signal port (127, 140, 250, 350) configured to: couple to a second duplex fiber which may simultaneously communicate in both the downstream and the upstream direction; and transmit a first modulated optical signal to the second duplex fiber wherein the first wavelength component and the second wavelength component comprise thin-film filters, TFFs, (117,120,143, 145) or optical circulators. an uncooled laser (105, 157, 205, 305); a splitter (110, 150, 215, 315) coupled to the laser (105, 157, 205, 305); a first wavelength component (117, 143, 215, 330) coupled to the splitter (110, 150, 215, 315), configured to pass a signal from the splitter (110, 150, 215, 315) to a local oscillator, LO, port (125, 137, 245, 345) and pass a signal from the LO port (125, 137, 245, 345) to a receiver; the LO port (125, 137, 245, 345) coupled to the first wavelength component (117, 143, 215, 330); a modulator (113, 153, 220, 320) coupled to the splitter (110, 150, 215, 315); a second wavelength component (120, 145, 235, 335) coupled to the modulator (113, 153, 220, 320), configured to pass a signal from the modulator (113, 153, 220, 320) to a signal port (127, 140, 250,350) and pass a signal from the signal port (127, 140, 250, 350) to the receiver; and the signal port (127, 140, 250, 350) coupled to the second wavelength component (120, 145, 235, 335), wherein the LO port (125, 137, 245, 345) is configured to: couple to a first duplex fiber which may simultaneously communicate in both the downstream and the upstream direction; and transmit a first LO optical signal to the first duplex fiber; and the signal port (127, 140, 250, 350) configured to: couple to a second duplex fiber which may simultaneously communicate in both the downstream and the upstream direction; and transmit a first modulated optical signal to the second duplex fiber wherein the first wavelength component and the second wavelength component comprise thin-film filters, TFFs, (117,120,143, 145) or optical circulators. couple to a first duplex fiber which may simultaneously communicate in both the downstream and the upstream direction; and transmit a first LO optical signal to the first duplex fiber; and the signal port (127, 140, 250, 350) configured to: couple to a second duplex fiber which may simultaneously communicate in both the downstream and the upstream direction; and transmit a first modulated optical signal to the second duplex fiber wherein the first wavelength component and the second wavelength component comprise thin-film filters, TFFs, (117,120,143, 145) or optical circulators. couple to a second duplex fiber which may simultaneously communicate in both the downstream and the upstream direction; and transmit a first modulated optical signal to the second duplex fiber wherein the first wavelength component and the second wavelength component comprise thin-film filters, TFFs, (117,120,143, 145) or optical circulators.