An apparatus comprising: an uncooled laser ; a splitter coupled to the laser ; a first wavelength component coupled to the splitter , configured to pass a signal from the splitter to a local oscillator, LO, port and pass a signal from the LO port to a receiver ; the LO port coupled to the first wavelength component ; a modulator coupled to the splitter ; a second wavelength component coupled to the modulator , configured to pass a signal from the modulator to a signal port and pass a signal from the signal port to the receiver ; and the signal port coupled to the second wavelength component , wherein the LO port 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 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, or optical circulators. an uncooled laser ; a splitter coupled to the laser ; a first wavelength component coupled to the splitter , configured to pass a signal from the splitter to a local oscillator, LO, port and pass a signal from the LO port to a receiver ; the LO port coupled to the first wavelength component ; a modulator coupled to the splitter ; a second wavelength component coupled to the modulator , configured to pass a signal from the modulator to a signal port and pass a signal from the signal port to the receiver ; and the signal port coupled to the second wavelength component , wherein the LO port 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 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, 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 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, 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, or optical circulators. <EOS>