Grating based optical parametric oscillator and method of dynamically tuning the oscillator for generating desired optical signals
View Patent ↗According to an embodiment of the present invention, an optical parametric oscillator (OPO) (e.g., for a laser transmitting device) includes non-linear optical media, optical beam manipulating elements, and a narrow linewidth filter in the form of a rotatable grating. The grating enables rapid tuning of the oscillator to provide an output beam with a desired wavelength. A pump laser provides a pump laser beam, and the non-linear optical media convert the pump beam into light beams with a signal wavelength and an idler wavelength. The angular positions or orientations of the non-linear optical media relative to a longitudinal propagation axis of the optical parametric oscillator (OPO) are adjustable to effectively tune the resulting signal and idler wavelengths. An output coupler receives the resulting beams from the non-linear optical media, and emits beams with the desired wavelength (signal and/or idler wavelengths).
1. An apparatus to generate a desired optical signal comprising:
an optical oscillator including:
at least one optical medium to produce optical medium signals with first and second wavelengths in response to an optical signal with a third wavelength traversing said at least one optical medium, wherein said desired optical signal includes said second wavelength;
a grating to produce a grating optical signal, wherein each angular orientation of said grating relative to a longitudinal axis of said optical oscillator produces said grating optical signal with a different wavelength range;
an optical element disposed between said grating and said at least one optical medium to direct corresponding optical signals toward said grating and said at least one optical medium and to remove said optical medium signals with said first wavelength from said optical oscillator, wherein said corresponding optical signals include said grating optical signal and said optical medium signals;
a beam expander coupled between said optical element and said grating to expand optical signals from said optical element on said grating and to compress optical signals received from said grating for said optical element;
a coupler coupled to said at least one optical medium to emit said desired optical signal from said optical oscillator with a desired linewidth and said second wavelength;
a plurality of rotating assemblies to rotate said grating and each said at least one optical medium to tune said optical oscillator to generate said desired optical signal; and
a control unit to scan across a tunable range of said optical oscillator, wherein said control unit is configured to:
receive user-specified parameters;
dynamically tune said optical oscillator and produce said desired optical signal for a time interval by controlling a configuration of said beam expander and said rotating assemblies to control angular orientations of said grating and said at least one optical medium in accordance with said user-specified parameters, wherein said grating is controlled and calibrated in accordance with a dispersion curve; and
adjust said rotating assemblies to adjust said angular orientations of said grating and said at least one optical medium after said time interval to produce said desired optical signal at a next desired wavelength in said scan and delay emission of said desired optical signal from said optical oscillator until optical signals from said adjusted angular orientations converge to said next desired wavelength.
2. The apparatus of claim 1 , wherein said desired optical signal includes a laser signal.
3. The apparatus of claim 1 , wherein said optical oscillator is tuned to produce said desired optical signal with a wavelength within a range of approximately 1.8-4 microns.
4. The apparatus of claim 1 , wherein said desired linewidth is less than 300 picometers.
5. The apparatus of claim 4 , wherein said desired linewidth is approximately 100 picometers.
6. The apparatus of claim 1 , wherein a thickness of said at least one optical medium is in the approximate range of two to four millimeters to produce said desired optical signal with a power level greater than one watt.
7. The apparatus of claim 1 , wherein said first wavelength includes a signal wavelength, said second wavelength includes an idler wavelength, and said coupler emits said desired optical signal including said idler wavelength.
8. The apparatus of claim 1 , further comprising:
a laser device to produce a laser signal; and
optics to manipulate said laser signal to form a pump signal compatible with said optical oscillator, and to provide said pump signal to said optical element within said optical oscillator.
9. The apparatus of claim 1 , wherein said desired linewidth enables detection of at least one of chemicals and biological entities.
10. The apparatus of claim 1 , wherein said control unit calibrates said grating based on measurements of said grating optical signal and signal dispersion curve.
11. A method of generating a desired optical signal within an optical oscillator comprising:
producing optical medium signals with first and second wavelengths via at least one rotatable optical medium in response to an optical signal with a third wavelength traversing said at least one optical medium, wherein said desired optical signal includes said second wavelength;
generating a grating optical signal via a rotatable grating, wherein each angular orientation of said grating produces said grating optical signal with a different wavelength range;
directing corresponding optical signals toward said grating and said at least one optical medium and removing optical medium signals with said first wavelength from said optical oscillator via an optical element, wherein said corresponding optical signals include said grating optical signal and said optical medium signals;
expanding optical signals from said optical element on said gating and compressing optical signals received from said grating for said optical element via a beam expander;
emitting said desired optical signal with a desired linewidth and a wavelength of said second wavelength via a coupler coupled to said at least one optical medium; and
scanning across a tunable range of said optical oscillator, via a control unit, by dynamically tuning said grating and each said at least one optical medium to generate said desired optical signal by rotating said grating and each said at least one optical medium, wherein said scanning includes:
receiving user-specified parameters;
controlling a configuration of said beam expander and angular orientations of said grating and said at least one optical medium in accordance with said user-specified parameters to dynamically produce said desired optical signal for a time interval, wherein said grating is controlled and calibrated in accordance with a dispersion curve; and
adjusting said angular orientations of said grating and said at least one optical medium after said time interval to produce said desired optical signal at a next desired wavelength in said scan and delaying emission of said desired optical signal from said optical oscillator until optical signals from said adjusted angular orientations converge to said next desired wavelength.
12. The method of claim 11 , wherein said desired optical signal includes a laser signal.
13. The method of claim 11 , wherein said tuning further includes:
tuning said grating and each said at least one optical medium to produce said desired optical signal with a wavelength within a range of approximately 1.8-4 microns.
14. The method of claim 11 , wherein said desired linewidth is less than 300 picometers.
15. The method of claim 14 , wherein said desired linewidth is approximately 100 picometers.
16. The method of claim 11 , wherein a thickness of said at least one optical medium is in the approximate range of two to four millimeters to produce said desired optical signal with a power level greater than one watt.
17. The method of claim 11 , wherein said first wavelength includes a signal wavelength, said second wavelength includes an idler wavelength, and said emitting further includes:
emitting said desired optical signal including a wavelength of said idler wavelength.
18. The method of claim 11 , further comprising:
producing a laser signal via a laser device;
manipulating said laser signal via optics to form a pump signal compatible with said at least one optical medium; and
directing said pump signal from said optics to said optical element.
19. The method of claim 11 , wherein said desired linewidth enables detection of at least one of chemicals and biological entities.
20. The method of claim 11 , further including:
calibrating said grating based on measurements of said grating optical signal and said dispersion curve.