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1. (WO2018202450) A METHOD OF WAVELENGTH TUNING FOR AN ONU AND AN ONU

Pub. No.:    WO/2018/202450    International Application No.:    PCT/EP2018/060273
Publication Date: Fri Nov 09 00:59:59 CET 2018 International Filing Date: Tue Apr 24 01:59:59 CEST 2018
IPC: H01S 5/06
H01S 5/024
H01S 5/068
H01S 5/12
Applicants: NOKIA SOLUTIONS AND NETWORKS OY
Inventors: POEHLMANN, Wolfgang
BRENOT, Romain
Title: A METHOD OF WAVELENGTH TUNING FOR AN ONU AND AN ONU
Abstract:
The present invention discloses a method of wavelength tuning for an optical network unit (100), the optical network unit comprising: a distributed feedback laser (110), configured to emit an optical signal, wherein, a wavelength of the optical signal changes with a temperature of the distributed feedback laser; a temperature sensor (120), configured to determine the temperature of the distributed feedback laser; a thermoelectric cooler (130), TEC, unit, configured to adjust the temperature of the distributed feedback laser within a first tuning range based on a first time constant, a heater unit (140), configured to adjust the temperature of the distributed feedback laser within a second tuning range based on a second time constant, the second tuning range being not bigger than the first tuning range, and the second time constant being smaller than the first time constant; the method comprising steps of: driving the TEC unit with a first current lx and driving the heater unit with a second current I2, so that the distributed feedback laser emits an optical signal with a first wavelength λ 1; receiving an indication of a second wavelength λ 2 to which the optical signal emitted by the distributed feedback laser shall be tuned; determining a third current I3 for the TEC unit and a fourth current I4 for the heater unit, so that the distributed feedback laser emits an optical signal with the second wavelength λ 2, when the TEC unit is driven by the third current and the heater unit is driven by the fourth current l4; adjusting the current that is used to drive the TEC unit from the first current lx at a first time point ti to the third current I3 at a second time point t2, adjusting the current that is used to drive the heater unit, so that the temperature of the distributed feedback laser is kept constant from the first time point ti to the second time point t2, the method further comprises a step of: tuning the wavelength of the optical signal emitted by the distributed feedback laser from the first wavelength λ 1 to the second wavelength λ 2 by adjusting the current that is used to drive the heater unit from the second current I2 to a fifth current l5 before the first time point, or from a fifth current l5 to the fourth current l4 after the second time point t2.