CN102969651A - Rapid K-space linear frequency sweep laser source - Google Patents

Abstract

The invention discloses a rapid K-space linear frequency sweep laser source. The laser source comprises a semiconductor optical amplifier, two polarization controllers, a dispersion control delay line, a circulator, a tuned filter and an output optical fiber coupler, wherein radiation light emitted from the semiconductor optical amplifier is transmitted to the dispersion control delay line through a polarization controller I; the middle port of the circulator is connected to the tuned filer through a first port of the circulator; returned signals are connected to the optical fiber coupler after passing through a third port of the circulator; one path of the optical fiber coupler outputs frequency sweep laser through a 60% port, and the other path of the optical fiber coupler is connected to the polarization controller II and then returns to a ring laser oscillation cavity; the tuned filter mainly comprises two dispersion elements, namely a grating and a prism, and a rotary polygonal mirror; and the linearity of a wave number space is achieved through combination of linear dispersion of the grating and non-linear dispersion of the prism as well as selection on the angles and directions of the prism. The rapid K-space linear frequency sweep laser source can be used for outputting the rapid K-space linear frequency sweep laser, and can obtain the signals of the linearity of the wave number space directly without calibration when being applied to an OCT (Optical Coherence Tomography) imaging system.

Description

The linear frequency-sweeping laser source in a kind of quick K space

Technical field

The present invention relates to frequency sweep Optical Coherence Tomography Imaging Technology field, be specifically related to the linear frequency-sweeping laser source in a kind of quick K space.

Background technology

Optical coherent chromatographic imaging (Optical Coherence Tomography is called for short OCT) belongs to a kind of harmless " optical biopsy " technology of coherent field optical imagery.Frequency sweep OCT has obtained all imaging depth scope internal informations in a frequency sweep cycle, thereby has greatly improved image taking speed, signal to noise ratio and sensitivity.Frequency sweep OCT realizes real time imagery, is applied at the body biomedical diagnostic.

The frequency sweep spectrum output wavelength of tradition swept light source all is linear, wave number does not have the exact linear relationship of time, this interference spectrum is non-linear the wave number space sampling, to cause the decline of axial resolution, the linearity correction of spectrum being carried out wave number space is the important step of guaranteeing system axial resolution and picture quality, and bearing calibration research has become the hot issue that each OCT group pays close attention to.The Chen group of University of California utilizes optical fibre Fabry-perot interferometer (FFPI) to carry out the correction of wave number space, and the equifrequent that the part light that this method is utilized the rapid frequency-sweeping light source produces by FFPI pectination signal spaced apart is as calibrating signal.The Fujimoto group of MIT utilizes Mach-Zehnder interferometer (MZI) to carry out frequency calibration, and the method is that the light beam of light source output is told a part of light by MZI, can form the interference fringe of proofreading and correct usefulness.The maximum of this interference fringe and minimum value all are that equifrequent is spaced apart, therefore can utilize these to be worth a little most and calibrate.These methods all need to introduce extra calibrator (-ter) unit, cause the raising of cost.The people such as Korea S Kim adopt the design of parabola slit, and by realizing wavelength linear to the conversion of K space linearity to speculum behind the parabola slit, still this method causes resolution very low behind the grating beam splitting.

In sum, how to break through wavelength linear to the conversion of wave number linearity, obtaining the linear frequency-sweeping laser source in quick K space is large technological difficulties.

Summary of the invention

The invention discloses the linear frequency-sweeping laser source in a kind of quick K space, adopt wavelength linear dispersion element grating and the combination of Nonlinear Dispersive component prisms, by selecting suitable prism angle and direction, be implemented in the linearity of wave number space, the frequency sweep spectrum that can effectively overcome traditional swept light source is non-linear owing to what sample at wave number space, cause axial resolution to descend, need to introduce extra calibrator (-ter) unit and carry out the correction of wave number space, so that cost improves, and the people such as Korea S Kim adopts parabola slit speculum to realize wavelength linear to the conversion of K space linearity, and resolution is lower drawback still.

Technical solution of the present invention is achieved in that

The linear frequency-sweeping laser source in a kind of quick K space comprises semiconductor optical amplifier, Polarization Controller one, Polarization Controller two, dispersion pilot delay line, circulator, tuned filter, 40%:60% output optical fibre coupler; Described tuned filter comprises the fiber optic collimator mirror, grating, prism, condenser lens, telescope, polygonal mirror, electric machine controller, plane mirror; Be characterized in:

A) the spontaneous excited radiation light that sends of described semiconductor optical amplifier through Polarization Controller one to the dispersion pilot delay line, the first port through circulator, the Centronics port of circulator connects tuned filter, the signal that returns is received the 40%:60% fiber coupler by circulator the 3rd port and is divided into two-way, one the tunnel through 60% port output sweeping laser, Polarization Controller two is received on another road, gets back to loop laser vibration chamber;

B) described tuned filter: from fiber optic collimator mirror collimated light out, through grating, arrive prism again, obtain wave number linear dispersion spectrum, it is directional light behind the line focus lens, the telescope that forms via lens one and lens two again, the bundle directional light that obtains contracting shines the polygonal mirror that electric machine controller drives, and reflexes to plane mirror; The polygonal mirror rotation, the different constantly gating different color lights of plane mirror reflect from Centronics port to the three ports of circulator by former road and enter loop laser vibration chamber.

Described tuned filter is grating-prism double dispersion elements combination, realizes the wave number linear dispersion by wavelength linear dispersion element and wavelength Nonlinear Dispersive elements combination.

Compare with background technology, the present invention has the following advantages and effect:

1, the introducing of dispersion pilot delay line realizes that light is at the time in one week of transmission in dispersion pilot delay line composition fiber ring laser vibration chamber and the tuning period coupling of grating-prism tuned filter, realization rapid scanning.

2, suitable prism angle and spectral illumination direction are selected in wavelength linear dispersion element grating and Nonlinear Dispersive component prisms combination, realize the effect of wave number linearity.

3, tuned filter is the combination of grating-prism double dispersion element, can realize meticulous tuningly, obtains high spectral resolution, can realize great imaging depth.

Description of drawings

Fig. 1 is the structural representation of the linear swept light source in the quick K of the present invention space;

Among the figure: 1. semiconductor optical amplifier, 2. Polarization Controller one, 3. the dispersion pilot delay line, 4. circulator, 5. output optical fibre coupler, 6. Polarization Controller two, 7. fiber optic collimator mirror, 8. grating, 9. prism, 10. condenser lens, 11. lens one, 12. lens two, 13. polygonal mirrors, 14. plane mirror, 15. electric machine controllers.

Embodiment

The present invention is described in detail below in conjunction with drawings and Examples.

As shown in Figure 1, the linear frequency-sweeping laser source in a kind of quick K space comprises semiconductor optical amplifier 1(InPhenix, Inc., IPSAD1301-L213), Polarization Controller 1, Polarization Controller 26, dispersion pilot delay line 3(Corning Inc., SMF28e), circulator 4,40%:60% output optical fibre coupler 5(Lightcomm Technology Co., Ltd., DWC-A-1*2-1315-40/60-1-0-FC/APC), fiber optic collimator mirror 7, grating 8, prism 9, condenser lens 10, lens 1, lens 2 12, polygonal mirror 13, plane mirror 14, electric machine controller 15;

The spontaneous excited radiation light that described semiconductor optical amplifier 1 sends arrives dispersion pilot delay line 3 through Polarization Controller 1, the first port through circulator 4, the Centronics port of circulator 4 is received tuned filter, the signal that returns is received 40%:60% fiber coupler 6 by circulator 4 the 3rd port and is divided into two-way, one the tunnel through 60% port output sweeping laser, Polarization Controller 27 is received on another road, gets back to loop laser vibration chamber.

The dispersion pilot delay line inserts in the chamber, so that getting over the cycle (light transmits a circle in the chamber time), photon mates with the tuning cycle of filter, as shown in Equation (1),

$\frac{L_{\mathrm{cavity}}}{V}={\mathrm{mT}}_{\mathrm{filter}}---\left(1\right)$

L in the formula _CavityThe chamber that is loop laser vibration chamber is long, and V is the light velocity in medium, and m is integer, represents harmonic number, T _FilterIt is the tuning cycle of tuned filter.The Fourier mode-locking technique of the dispersion pilot delay line of this long optical fibers based on several kms, when the arrowband coloured light that filter leaches transmitted a circle to filter in the chamber, being filter tuner just, one-period passed through the position to this arrowband coloured light again.The all wavelengths pattern forms resonance simultaneously in resonant cavity, successively by tuned filter and by coupler output sweeping laser, thereby obtained quasi-continuous pattern output.Only be subject to the maximum tuned speed of filter based on the sweep velocity of the swept light source of Fourier mode-locking technique, therefore can realize the high speed frequency sweep.

As shown in Figure 1: described tuned filter is by fiber optic collimator mirror 7, grating 8, and prism 9, the telescope that condenser lens 10, lens 1 and lens 2 12 form, polygonal mirror 13, electric machine controller 14, plane mirror 15 consists of.From fiber optic collimator mirror 7 collimated light out, through grating 8 light splitting, obtain the spectrum of wavelength linear dispersion, arrive again prism 9, further dispersion, prism is wavelength Nonlinear Dispersive element, two dispersion element combinations, choose prism angle and direction of illumination, obtain the linear dispersion spectrum in K space, become directional light behind the line focus lens 10, directional light obtains contracting Shu Guang through the telescope that is comprised of lens 1 and lens 2 12, polygonal mirror 13 through electric machine controller 14 drivings reflexes to plane mirror 15, and during the polygonal mirror rotation, the different wave number coloured light of gating at quarter in stopping time do not reflect by former road and enter the formation laser generation of loop laser vibration chamber; Grating-prism tuning filtering mainly is comprised of dispersion grating, prism combination dispersion system and polygonal rotating mirror, has not only solved the problem of wave number linearity, and has improved the angle dispersion ability, obtains more meticulous spectrum than monochromatic light grid.

The invention discloses the linear output in a kind of quick K space frequency-sweeping laser source.The Fourier locked mode frequency-sweeping laser source based on the dispersion pilot delay line is adopted in loop laser vibration chamber.Tuned filter is grating-prism double dispersion elements combination, realizes the wave number linear dispersion by wavelength linear dispersion element and wavelength Nonlinear Dispersive elements combination, and has improved dispersive power, realizes the function of fine tuning, obtains the catch light spectral resolution.The present invention can realize fast, the K space linear, the output of the sweeping laser of high spectral resolution, has solved the linear problem of wave number space sampling in the frequency sweep Optical Coherence Tomography Imaging Technology, has improved picture quality.Be applied in frequency sweep OCT imaging system, need not demarcate the signal that directly obtains the wave number space linearity.

Claims (2)

1. the linear frequency-sweeping laser source in quick K space comprises semiconductor optical amplifier, Polarization Controller one, Polarization Controller two, dispersion pilot delay line, circulator, tuned filter, 40%:60% output optical fibre coupler; Described tuned filter comprises the fiber optic collimator mirror, grating, prism, condenser lens, telescope, polygonal mirror, electric machine controller, plane mirror; It is characterized in that:

A) the spontaneous excited radiation light that sends of described semiconductor optical amplifier through Polarization Controller one to the dispersion pilot delay line, the first port through circulator, the Centronics port of circulator connects tuned filter, the signal that returns is received the 40%:60% fiber coupler by circulator the 3rd port and is divided into two-way, one the tunnel through 60% port output sweeping laser, Polarization Controller two is received on another road, gets back to loop laser vibration chamber;

B) described tuned filter: from fiber optic collimator mirror collimated light out, through grating, arrive prism again, obtain wave number linear dispersion spectrum, it is directional light behind the line focus lens, the telescope that forms via lens one and lens two again, the bundle directional light that obtains contracting shines the polygonal mirror that electric machine controller drives, and reflexes to plane mirror; The polygonal mirror rotation, the different constantly gating different color lights of plane mirror reflect from Centronics port to the three ports of circulator by former road and enter loop laser vibration chamber.

2. the linear frequency-sweeping laser source in a kind of quick K according to claim 1 space, it is characterized in that: described tuned filter is grating-prism double dispersion elements combination, realizes the wave number linear dispersion by wavelength linear dispersion element and wavelength Nonlinear Dispersive elements combination.

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