Diode laser frequency doubling using nonlinear crystal resonator with electronic resonance locking
First Claim
1. A semiconductor laser apparatus comprising:
- a DC power supply coupled with an RF source generating a low-amplitude RF current;
a diode laser source receiving an injection current from the DC power supply and the coupled RF current source emitting a laser beam with a central carrier frequency having low-amplitude frequency sidebands generated by the RF current;
an optical beam shaping system for processing and directing the laser beam emitted from the diode laser source;
a nonlinear resonator having a plurality of longitudinal resonator frequencies with a fundamental spatial mode receiving the optically-shaped laser beam, said optically-shaped beam substantially matching the fundamental spatial profile and the central carrier frequency substantially matching one of the longitudinal resonator frequencies;
said nonlinear resonator using a phase-matched, second harmonic generation (SHG) process for generating a second laser beam by frequency doubling the central carrier frequency of the diode laser source, and further reflecting a portion of the incident optically-shaped laser beam to an electronic resonance locking system;
said electronic resonance locking system having a photodetector receiving the reflected portion of the optically-shaped beam from the resonator and generating an RF signal arising from the difference in phase shifts or amplitudes between said RF sidebands caused by any frequency mismatch between the central laser frequency and said substantially matched longitudinal resonator frequency; and
said electronic frequency locking system further including an RF mixer electrically coupled to the diode laser source receiving the RF signal from the photodetector and an input from the RF source for generating an error signal as a feedback signal which is supplied to the diode laser source for tuning the laser injection current or the diode temperature,whereby the diode laser central carrier frequency is controlled by the tuning of the injection current or diode temperature to track the substantially matched longitudinal resonator frequency.
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Accused Products
Abstract
A semiconductor laser apparatus comprises a DC power supply coupled with an RF source which generates a low-amplitude RF current which is injected into a diode laser source. An optical beam shaping system processes the laser beam and directs it to a nonlinear resonator having a plurality of longitudinal resonator frequencies with a fundamental spatial mode. The nonlinear resonator uses a phase-matched, second harmonic generation (SHG) process to generate a second laser beam by frequency doubling the central carrier frequency of the diode laser source, and further reflects a portion of the incident laser beam to an electronic resonance locking system. The electronic resonance locking system has a photodetector to receive the reflected portion of the incident beam from the resonator and generates an RF signal arising from the difference in phase shifts or amplitude losses experienced by the RF sidebands. An RF mixer receives the RF signal from the photodetector and an input from the RF source to generate an error signal as a feedback signal which is supplied to the diode laser source for tuning the laser injection current.
35 Citations
17 Claims
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1. A semiconductor laser apparatus comprising:
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a DC power supply coupled with an RF source generating a low-amplitude RF current; a diode laser source receiving an injection current from the DC power supply and the coupled RF current source emitting a laser beam with a central carrier frequency having low-amplitude frequency sidebands generated by the RF current; an optical beam shaping system for processing and directing the laser beam emitted from the diode laser source; a nonlinear resonator having a plurality of longitudinal resonator frequencies with a fundamental spatial mode receiving the optically-shaped laser beam, said optically-shaped beam substantially matching the fundamental spatial profile and the central carrier frequency substantially matching one of the longitudinal resonator frequencies; said nonlinear resonator using a phase-matched, second harmonic generation (SHG) process for generating a second laser beam by frequency doubling the central carrier frequency of the diode laser source, and further reflecting a portion of the incident optically-shaped laser beam to an electronic resonance locking system; said electronic resonance locking system having a photodetector receiving the reflected portion of the optically-shaped beam from the resonator and generating an RF signal arising from the difference in phase shifts or amplitudes between said RF sidebands caused by any frequency mismatch between the central laser frequency and said substantially matched longitudinal resonator frequency; and said electronic frequency locking system further including an RF mixer electrically coupled to the diode laser source receiving the RF signal from the photodetector and an input from the RF source for generating an error signal as a feedback signal which is supplied to the diode laser source for tuning the laser injection current or the diode temperature, whereby the diode laser central carrier frequency is controlled by the tuning of the injection current or diode temperature to track the substantially matched longitudinal resonator frequency.
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2. A semiconductor laser apparatus comprising:
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a DC power supply coupled to an RF source generating a low-amplitude RF current; a gallium-aluminum-arsenide diode laser source receiving an injection current from the DC power supply and the coupled RF current source emitting a laser beam with a central carrier frequency corresponding to a wavelength of approximately 860 nm having low-amplitude frequency sidebands generated by the RF current; an optical beam shaping system for processing and directing the laser beam emitted from the diode laser source; a potassium niobate nonlinear resonator having a plurality of longitudinal resonator frequencies and an associated fundamental spatial mode, said optically-shaped beam matching substantially to the fundamental spatial mode and said central carrier frequency matching substantially one of the longitudinal resonator frequencies; said nonlinear resonator receiving the optically-shaped laser beam using a phase-matched, second harmonic generation (SHG) process for generating a second laser beam in the blue spectral region by frequency doubling said central carrier frequency, and further reflecting a portion of the incident optically-shaped laser beam to an electronic resonance locking system; said electronic resonance locking system having a photodetector receiving the reflected portion of the optically-shaped beam from the resonator and generating an RF signal arising from the difference in phase shifts or amplitudes between said RF sidebands caused by any frequency mismatch between the central carrier frequency and the substantially matched longitudinal resonator frequency; and said electronic frequency locking system further including an RF mixer electrically coupled to the diode laser source receiving the RF signal from the photodetector and an input from the RF source for generating an error signal as a feedback signal which is supplied to the diode laser source for tuning the laser injection current or diode temperature, whereby the diode laser central carrier frequency is controlled by the tuning of the injection current or diode temperature to track the substantially matched longitudinal resonator frequency of the potassium niobate nonlinear resonator. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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9. A process to generate a laser beam comprising the steps of:
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injecting a DC current coupled with a low-amplitude RF current to a laser diode source for generating a laser beam having a central carrier frequency and low-amplitude frequency sidebands; optically shaping and directing the laser beam into a nonlinear resonator, said resonator having a plurality of longitudinal resonant frequencies with a fundamental spatial mode, said optically-shaped beam substantially matching the fundamental spatial mode and said central carrier frequency matching substantially one of the longitudinal resonator frequencies; transmitting the laser beam through the resonator using a phase-matched, second harmonic generation (SHG) process generating a second laser beam by frequency doubling the central carrier frequency; reflecting a portion of the optically-shaped incident beam from the resonator to a photodetector; generating an RF signal using the difference in phase shifts or amplitudes of the sidebands caused by any frequency mismatch between the central carrier frequency and the substantially matched resonator frequency; generating an error signal corresponding to said RF signal coupling with an input from the low-amplitude RF current; and tuning the laser injection current by coupling to the DC current and the low-amplitude RF current or diode temperature by using the error signal as feedback, whereby the central carrier frequency of the diode laser source is controlled by said tuning of the injection current or diode temperature to track the substantially matched longitudinal resonator frequency.
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10. A process to generate a laser beam in the blue spectral region comprising the steps of:
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injecting a DC current coupled with a low-amplitude RF current to a GaAlAs laser diode source for generating a laser beam having a central carrier frequency with a corresponding wavelength of approximately 860 nm and low-amplitude frequency sidebands; optically shaping and directing the laser beam into a nonlinear resonator, said resonator having a plurality of longitudinal resonant frequencies with a fundamental spatial mode, said optically-shaped beam substantially matching the fundamental spatial mode and said central carrier frequency matching substantially one of the longitudinal resonator frequencies; transmitting the laser beam through the ring resonator using a phase-matched, second harmonic generation (SHG) process for generating a second laser beam in the blue spectral region by doubling the central carrier frequency of the diode laser; reflecting a portion of the optically-shaped incident beam from the resonator to a photodetector; generating an RF signal by using the difference in phase shifts or amplitudes between the low-amplitude sidebands caused by any frequency mismatch between the central carrier frequency and the substantially matched resonator frequency; generating an error signal corresponding to said RF signal coupling with an input from the low-amplitude RF current; and tuning the laser injection current by coupling to the DC current and the low-amplitude RF current or diode temperature by using the error signal as feedback, whereby the central carrier frequency of the diode laser is controlled by said tuning of the injection current or diode temperature to track the substantially matched longitudinal resonator frequency of the nonlinear resonator. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A laser data storage system having a laser source, an optical recording medium, an optical transmission means for directing a laser beam emitted from the laser source to the optical recording medium, and an optical reception means for receiving a reflected laser beam from the optical recording medium and proving a data signal responsive thereto, wherein said laser source further comprising:
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a DC power supply coupled with an RF source generating a low-amplitude RF current; a diode laser source receiving an injection current from the DC power supply and the coupled RF current source emitting a laser beam with a central carrier frequency having low-amplitude frequency sidebands generated by the RF current; an optical beam shaping system for processing and directing the laser beam emitted from the diode laser source; a nonlinear resonator having a plurality of longitudinal resonator frequencies with a fundamental mode receiving the optically-shaped laser beam, said optically-shaped beam substantially matching the fundamental spatial profile and the central carrier frequency substantially matching one of the longitudinal resonator frequencies; said nonlinear resonator using a phase-matched, second harmonic generation (SHG) process for generating a second laser beam by frequency doubling the central carrier frequency of the diode laser source and further reflecting a portion of the incident optically-shaped laser beam to an electronic resonance locking system; said electronic resonance locking system having a photodetector receiving the reflected portion of the optically-shaped beam from the resonator and generating an RF signal arising from the difference in phase shifts or amplitudes between said RF sidebands caused by any frequency mismatch between the central laser frequency and said substantially matched longitudinal resonator frequency; and said electronic frequency locking system further including an RF mixer electrically coupled to the diode laser source receiving the RF signal from the photodetector and an input from the RF source for generating an error signal as a feedback signal which is supplied to the diode laser source for tuning the laser injection current or the diode temperature, whereby the diode laser central carrier frequency is controlled by said tuning of the injection current or diode temperature to track the substantially matched longitudinal resonator frequency.
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17. A magneto-optical disk storage system in which data is stored and read from a plurality of data tracks disposed on a disk, said storage system having a magnetic field source for generating a magnetic field for data recording, erasing, and reading, said storage system further including a laser source generating at least a laser beam and an optical system to focus the laser beam onto the disk tracks for the recording, erasing, or reading processes, said storage system further including a control system controlling the track access, the laser intensity, and focuses, said laser source comprising:
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a DC power supply coupled with an RF source generating a low-amplitude RF current; a diode laser source receiving an injection current from the DC power supply and the coupled RF current source emitting a laser beam with a central carrier frequency having low-amplitude frequency sidebands generated by the RF current; an optical beam shaping system for processing and directing the laser beam emitted from the diode laser source; a nonlinear resonator having a plurality of longitudinal resonator frequencies with a fundamental mode receiving the optically-shaped laser beam, said optically-shaped beam substantially matching the fundamental spatial profile and the central carrier frequency substantially matching one of the longitudinal resonator frequencies; said nonlinear resonator using a phase-matched, second harmonic generation (SHG) process for generating a second laser beam by frequency doubling the central carrier frequency of the diode laser source and further reflecting a portion of the incident optically-shaped laser beam to an electronic resonance locking system; said electronic resonance locking system having a photodetector receiving the reflected portion of the optically-shaped beam from the resonator and generating an RF signal arising from the difference in phase shifts or amplitudes between said RF sidebands caused by any frequency mismatch between the central laser frequency and said substantially matched longitudinal resonator frequency; and said electronic frequency locking system further including an RF mixer electrically coupled to the diode laser source receiving the RF signal from the photodetector and an input from the RF source for generating an error signal as a feedback signal which is supplied to the diode laser source for tuning the laser injection current or the diode temperature, whereby the diode laser central carrier frequency is controlled by said tuning of the injection current or diode temperature to track the substantially matched longitudinal resonator frequency.
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Specification