PAIR OF OPTICALLY LOCKED SEMICONDUCTOR NARROW LINEWIDTH EXTERNAL CAVITY LASERS WITH FREQUENCY OFFSET TUNING
First Claim
1. An optical phase lock loop (OPLL) system, comprising:
- a master external cavity laser (ECL) comprising a planar semiconductor device with waveguide-integrated planar Bragg gratings (PBG), and having a narrow linewidth and a low frequency-noise;
a slave ECL, substantially similar to the master ECL, with an adjustable frequency offset with respect to the master ECL;
a master controller-modulator configured to control a temperature and current modulation of the master ECL, having a frequency response that accommodates characteristics of the master ECL;
a slave controller-modulator, substantially similar to the master controller-modulator, configured to control a temperature and current modulation of the slave ECL, having a frequency response that accommodates characteristics of the slave ECL;
a heterodyne receiver that receives a coherent heterodyne optical beat signal from the master and the slave ECLs via optical components, and outputs an amplified electronic beat frequency signal in a microwave frequency range;
a direct digital synthesizer (DDS) module that supplies a control frequency;
an electronic phase lock loop (PLL) module that receives the amplified electronic beat frequency signal from the heterodyne receiver, and also receives the control frequency from the DDS, and generates an error signal;
a loop filter that receives the error signal, and provides gain in a bandwidth of the frequency response range of the master and slave controller-modulators; and
a laser-select-logic (LSL) module that receives and processes a filtered error signal from the loop filter, and directs the processed error signal to one or both of the master and slave controller-modulators according to a logical determination of one or more required modes of operation of the OPLL system in order to achieve a stable and identical phase performance of the master and the slave ECLs.
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Accused Products
Abstract
An optical phase lock loop (OPLL) system is disclosed that includes a master external cavity laser (ECL), and a substantially identical slave ECL. The master and slave ECLs are fabricated using a planar semiconductor device with waveguide-integrated planar Bragg gratings (PBG). Both the master and slave ECLs have a narrow linewidth and a low frequency-noise. Each of the ECLs has their own controller-modulator circuits for thermal tuning or electrical tuning via direct modulation. A laser-select-logic (LSL) module receives and processes a filtered phase error signal from a loop filter coupled to an electronic PLL device, and directs the processed phase error signal to one or both of the master and slave controller-modulators according to a logical determination of a required mode of operation of the OPLL system in order to achieve a stable and identical phase performance of the master and the slave ECLs. The required mode of operation is chosen from a locking mode, a prediction mode, a tracking mode, and a searching mode.
77 Citations
17 Claims
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1. An optical phase lock loop (OPLL) system, comprising:
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a master external cavity laser (ECL) comprising a planar semiconductor device with waveguide-integrated planar Bragg gratings (PBG), and having a narrow linewidth and a low frequency-noise; a slave ECL, substantially similar to the master ECL, with an adjustable frequency offset with respect to the master ECL; a master controller-modulator configured to control a temperature and current modulation of the master ECL, having a frequency response that accommodates characteristics of the master ECL; a slave controller-modulator, substantially similar to the master controller-modulator, configured to control a temperature and current modulation of the slave ECL, having a frequency response that accommodates characteristics of the slave ECL; a heterodyne receiver that receives a coherent heterodyne optical beat signal from the master and the slave ECLs via optical components, and outputs an amplified electronic beat frequency signal in a microwave frequency range; a direct digital synthesizer (DDS) module that supplies a control frequency; an electronic phase lock loop (PLL) module that receives the amplified electronic beat frequency signal from the heterodyne receiver, and also receives the control frequency from the DDS, and generates an error signal; a loop filter that receives the error signal, and provides gain in a bandwidth of the frequency response range of the master and slave controller-modulators; and a laser-select-logic (LSL) module that receives and processes a filtered error signal from the loop filter, and directs the processed error signal to one or both of the master and slave controller-modulators according to a logical determination of one or more required modes of operation of the OPLL system in order to achieve a stable and identical phase performance of the master and the slave ECLs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification