Patent ID: 9065251
Filing Date: 2015-06-23
Classification: H01S

Abstract:
1. A wavelength monitor integrated with a tunable laser diode (LD) to form a wavelength lockable LD, comprising: a base photodiode (PD) configured to monitor light generated by the tunable LD; a first optical filter to transmit the light generated by the tunable transmitted through the base PD and a first waveguide, the first optical filter having a first transmittance spectrum periodically varying in a wavelength range of a wavelength division multiplexing (WDM) system; a first PD configured to monitor first light generated by the tunable LD, transmitted through the base PD, the first waveguide, and the first filter, the first transmittance depending on the base PD and the first PD; a second optical filter to transmit the light generated by the tunable LD, transmitted through the base PD and a second waveguide, the second optical filter having a second transmittance spectrum periodically varying in the wavelength range of the WDM system; and a second PD configured to monitor second light generated by the tunable LD, transmitted through the base PD, the second waveguide, and the second filter, the second transmittance depending on the PD and the second PD, wherein the first transmittance spectrum and the second transmittance spectrum at a grid wavelength of the WDM system have a combination in respective transmittances specific to the grid wavelength different from combinations of respective transmittances at other grid wavelengths of the WDM system, wherein the first filter and the second filter are disposed in parallel with respect to the base PD, and wherein the wavelength monitor selects one of the first filter and the second filter based upon which of the first filter and the second filter has a larger slope or a greater rate of change in transimittance spectra at grid wavelength within the grid wavelength spectrum of the WDM system.