Summary of the invention
At the deficiency in the background technology, the object of the present invention is to provide a kind of based on the active resonant cavity and the optical sensor of the passive resonant cavity of cascade with it.
The technical solution used in the present invention is as follows:
Technical scheme 1:
The present invention includes the active resonant cavity of launching pectination spontaneous emission spectrum uniformly-spaced or laser spectrum that has internal gain and have the uniformly-spaced passive resonant cavity of comb filtering spectrum, and optical power detector; Active resonant cavity is identical with the optical length of passive resonant cavity, at least be provided with the passive resonant cavity sensing unit that one section optical length can change with external environment in the passive resonant cavity, the spectrum of an output port emission of active resonant cavity is input to passive resonant cavity, is received by an optical power detector after the filtering through passive resonant cavity again.
Described active resonant cavity is active Fabry-Perot cavity, active ring resonator or the inner multisection type active resonant cavity that has the distributed Feedback optical grating construction.
Described passive resonant cavity is passive annular resonant cavity, passive Fabry-Perot cavity or the inner multisection type passive resonant cavity that has the distributed Feedback optical grating construction.
Described active resonant cavity is one and has applied the cycle microwave-driven signal identical with the cycle of operation of photon in active resonant cavity, thereby keeps its emission spectrum not to be subjected to the active resonant cavity of external interference.
Another output port place of described active resonant cavity is provided with another optical power detector.
Technical scheme 2:
The present invention includes the active resonant cavity of launching pectination spontaneous emission spectrum uniformly-spaced or laser spectrum that has internal gain and have the uniformly-spaced passive resonant cavity of comb filtering spectrum, and spectrometer; Active resonant cavity is different with the optical length of passive resonant cavity, at least be provided with the passive resonant cavity sensing unit that one section optical length can change with external environment in the passive resonant cavity, the spectrum of an output port emission of active resonant cavity is input to passive resonant cavity, is received by spectrometer after the filtering through passive resonant cavity again.
Described active resonant cavity is active Fabry-Perot cavity, active ring resonator or the inner multisection type active resonant cavity that has the distributed Feedback optical grating construction.
Described passive resonant cavity is passive annular resonant cavity, passive Fabry-Perot cavity or the inner multisection type passive resonant cavity that has the distributed Feedback optical grating construction.
Described active resonant cavity is one and has applied the cycle microwave-driven signal identical with the cycle of operation of photon in active resonant cavity, thereby keeps its emission spectrum not to be subjected to the active resonant cavity of external interference.
Compare with background technology, the beneficial effect that the present invention has is:
The filter effect of the present invention uses active-passive cascade dual resonant cavity, when active when identical with the passive resonant cavity optical length, only need simply just to obtain the variation of measurand with the variation that optical power detector is measured output light intensity in the full spectral range, no longer need to obtain the information of spectral correlation by spectrometer, reduce the device detection cost, use multimode active resonant cavity with low cost such as Fabry-Perot (Fabry-Perot) chamber as the input light source, reduce the cost that device production is made, and, by active and passive element integrated technology, need not external light source, also eliminated highly difficult, the demand of expensive sensing waveguide optically-coupled.Further, when active and passive resonant cavity optical length is inequality, obtain the output spectrum of two resonator cavity cursor effects, can further expand measurement range, improve measuring accuracy by spectrometer.By from above several angles, optical sensor of the present invention is compared traditional passive optical sensors cost and is reduced greatly, uses with test more easy.
Description of drawings
Fig. 1 is based on the passive optical waveguide sensor synoptic diagram of single ring resonator in the background technology.
Fig. 2 is first kind of embodiment structural representation of the present invention.
Fig. 3 is that active Fabry-Perot cavity and passive annular resonant cavity optical path difference are the fluorescence emission spectrum of 0 o'clock active Fabry-Perot cavity and the transmission spectrum of passive annular resonant cavity in first kind of embodiment of the present invention.
Fig. 4 is that active Fabry-Perot cavity and passive annular resonant cavity optical path difference are the fluorescence emission spectrum and the passive annular resonant cavity transmission spectrum stack result of 0 o'clock active Fabry-Perot cavity in first kind of embodiment of the present invention.
Fig. 5 is active Fabry-Perot cavity and the fluorescence emission spectrum of non-0 o'clock active Fabry-Perot cavity of passive annular resonant cavity optical path difference and the transmission spectrum of passive annular resonant cavity in first kind of embodiment of the present invention.
Fig. 6 is the fluorescence emission spectrum and the passive resonant cavity transmission spectrum stack result of active Fabry-Perot cavity and non-0 o'clock active resonant cavity of passive annular resonant cavity optical path difference in first kind of embodiment of the present invention.
Fig. 7 is the curve that optical power detector detects in first kind of embodiment of the present invention luminous power is led variations in refractive index with the equivalence of passive annular resonant cavity ripple.
Fig. 8 is second kind of embodiment structural representation of the present invention.
Fig. 9 is the third embodiment structural representation of the present invention.
Figure 10 is the 4th kind of embodiment structural representation of the present invention.
Figure 11 is the 5th kind of embodiment structural representation of the present invention.
Figure 12 is the 6th kind of embodiment structural representation of the present invention.
Figure 13 is a plurality of longitudinal modes of active Fabry-Perot cavity and passive annular resonant cavity.And the material gain of active cavity spectrum.
Figure 14 is that the passive annular resonant cavity refractive index is the fluorescence emission spectrum of 3.215 o'clock active Fabry-Perot cavities and the transmission spectrum of passive annular resonant cavity in the 6th kind of embodiment of the present invention.
Figure 15 is that the passive annular resonant cavity refractive index is the fluorescence emission spectrum and the passive annular resonant cavity transmission spectrum stack result of 3.215 o'clock active Fabry-Perot cavities in the 6th kind of embodiment of the present invention.
Figure 16 is that the passive annular resonant cavity refractive index is the fluorescence emission spectrum of 3.2155 o'clock active Fabry-Perot cavities and the transmission spectrum of passive annular resonant cavity in the 6th kind of embodiment of the present invention.
Figure 17 is that the passive annular resonant cavity refractive index is the fluorescence emission spectrum and the passive annular resonant cavity transmission spectrum stack result of 3.2155 o'clock Fabry-Perot cavities in the 6th kind of embodiment of the present invention.
Figure 18 is fluorescence emission spectrum and the passive annular resonant cavity transmission spectrum stack result that spectrometer receives two pattern energy Fabry-Perot cavity when suitable in the 6th kind of embodiment of the present invention.
Among the figure: 1, active Fabry-Perot cavity, 2, passive annular resonant cavity, 3, an optical power detector, 11, the microwave-driven signal that cycle and the photon cycle of operation in active resonant cavity is close, 12, active Fabry-Perot cavity first catoptron, 13, active Fabry-Perot cavity second catoptron, 20, the passive annular resonant cavity passive waveguide region, 21, the passive annular resonant cavity sensing unit, 22, first passive wave guide, 23, second passive wave guide, 4, passive Fabry-Perot cavity, 40, passive Fabry-Perot cavity passive waveguide region, 41, passive Fabry-Perot cavity sensing unit, 42, passive Fabry-Perot cavity first catoptron, 43, passive Fabry-Perot cavity second catoptron, 5, active ring resonator, 51, the 3rd passive wave guide, 6, another optical power detector, 7, spectrometer.
Embodiment
The present invention is further illustrated below in conjunction with drawings and Examples.
Fig. 2 the present invention is based on active resonant cavity and first kind of embodiment of the optical sensor of the passive resonant cavity of cascade with it.Which comprises at least an active Fabry-Perot cavity 1 that has an internal gain and one and have the uniformly-spaced passive annular resonant cavity 2 of comb filtering spectrum with the output of pectination spectrum uniformly-spaced, and an optical power detector 3; Active Fabry-Perot cavity is identical with the optical length of passive annular resonant cavity, be provided with the passive annular resonant cavity sensing unit 21 that one section optical length can change with external environment in the passive annular resonant cavity, the spectrum of active Fabry-Perot cavity emission is input to passive annular resonant cavity by first passive wave guide 22, through after the filtering of passive annular resonant cavity, received by an optical power detector 3 by second passive wave guide 23.
Active Fabry-Perot cavity is made of gain region and active Fabry-Perot cavity first catoptron 12 and active Fabry-Perot cavity second catoptron 13 that are positioned at its both ends of the surface among the figure.The photon of spontaneous radiation is exaggerated in gain region, is reflected back toward in two catoptrons, 12,13 place's parts and continues in the active cavity to obtain to amplify, and another part then sees through active Fabry-Perot cavity second catoptron 13 outgoing and forms the pectination emission spectrum.Passive annular resonant cavity 2 is by passive annular resonant cavity passive waveguide region 20, and passive annular resonant cavity sensing unit 21 constitutes.The spectrum of active Fabry-Perot cavity emission is received by optical power detector through after the filtering outgoing of passive annular resonant cavity.Passive annular resonant cavity is connected with optical power detector with active Fabry-Perot cavity respectively by first and second passive wave guides.
The luminous power P that optical power detector monitors can be expressed as:
Wherein I (ω) represents the emission spectrum of active Fabry-Perot cavity 1, the filtering spectral line of T (ω) expression passive annular resonant cavity 2.As a rule, the emission spectrum live width of active Fabry-Perot cavity 1 is far smaller than the filtering spectrum of passive annular resonant cavity 2, therefore has:
ω wherein
k=k π c/L
1, be the k level resonance frequency of active Fabry-Perot cavity 1, c is the light velocity, L
1It is the optical length of active resonant cavity 1.Δ (ω) is an impulse function, and F (ω) is the envelope of emission spectrum, ω
K0It is emission spectrum envelope peak frequency.
For passive annular resonant cavity, its filter function can be expressed as:
Wherein C be passive annular resonant cavity with the straight-through coupling coefficient of coupling mechanism, L
2Be half of optical length of passive annular resonant cavity, ω is an angular frequency, and c is the light velocity in the vacuum, T
0Be constant.
(2) (3) substitutions (1) can be got:
L wherein
1Be the optical length of active resonant cavity, Δ L=L
2-L
1, Δ k=k-k
0In general active resonant cavity 1 luminescence spectrum scope, little if sensing scope changes, can have Δ L<<L
1With Δ k<<k
0,, therefore can ignore high-order a small amount of 2 π Δ k (Δ the L)/L in (4) formula denominator
1, (4) formula can be transformed to:
Wherein
Represent the general power that active Fabry-Perot cavity sends.By formula (5) as can be seen, the power P that optical power detector receives is relevant with the light path discrepancy delta L of active Fabry-Perot cavity and passive annular resonant cavity, when Δ L is 0, and the power maximum that optical power detector receives, two light paths depart from many more, and the power that then receives is more little.Therefore, when the optical length of sensing unit 21 is subjected to the external environment factor such as stress, when temperature or measured matter concentration etc. changed, the total optical length of passive annular resonant cavity will change, cause Δ L to change, thereby cause the optical power change that optical power detector receives.By measuring this variable power, just can obtain information measured such as stress, temperature.
It is 200 μ m that Fig. 3 has provided a length, refractive index is 3.215, operation wavelength is suitable with this active resonant cavity with refractive index in fluorescence emission spectrum and length that the active Fabry-Perot cavity of 1550nm is operated in below the threshold current, and girth is the transmission spectrum of the passive annular resonant cavity of 400 μ m.At this moment, the light path discrepancy delta L of two resonator cavitys is 0, and the transmission spectrum peak value of the fluorescence emission spectrum of active resonant cavity and passive resonant cavity is aligned with each other, and the power that active resonant cavity is launched is 4.823mW.Fig. 4 is active Fabry-Perot cavity fluorescence emission spectrum and the passive annular resonant cavity transmission spectrum result after the stack mutually, i.e. the output power spectrum of whole sensor, and calculating the gross output that optical power detector detects is 3.995mW.
When the refractive index of passive resonant cavity because of the external environment influence when 3.215 become 3.217, the fluorescence emission spectrum of active resonant cavity and the transmission spectrum of passive resonant cavity are as shown in Figure 5, this moment is because the change of sensing unit equivalent refractive index, the light path in two chambeies has had little difference, the transmission spectrum peak value of the fluorescence emission spectrum of active resonant cavity and passive resonant cavity staggers mutually, and the power that active resonant cavity is launched is still 4.823mW.Fig. 6 is active Fabry-Perot cavity fluorescence emission spectrum and the passive annular resonant cavity transmission spectrum result after the stack mutually, and calculating the gross output that optical power detector detects is 0.2862mW.
Fig. 7 is the curve of Output optical power with the passive annular resonant cavity variations in refractive index, and as seen, the subtle change of refractive index just can cause the variation of sensor Output optical power.In variations in refractive index 0~4 * 10
-4Scope in, variable power is linear substantially, we can utilize this zone to do sensing.
By above-mentioned example as seen, when active resonator cavity is operated in threshold value when following, can change by the output power of acquisition sensor just can obtain variations such as extraneous stress, temperature.When being operated in threshold value, active resonator cavity can obtain similar Effect on Detecting equally when above.
Fig. 8 the present invention is based on active resonant cavity and second embodiment of the optical sensor of the passive resonant cavity of cascade with it, it comprises the active ring resonator 5 of launching pectination spontaneous emission spectrum uniformly-spaced or laser spectrum that has internal gain and has the uniformly-spaced passive annular resonant cavity 2 of comb filtering spectrum, and an optical power detector 3, active ring resonator links to each other with passive annular resonant cavity by the 3rd passive wave guide 51.In addition, active ring resonator can also be the active resonant cavity that the inside multisection type active resonant cavity that has the distributed Feedback optical grating construction etc. is exported pectination spontaneous emission spectrum uniformly-spaced or laser spectrum.
Fig. 9 the present invention is based on active resonant cavity and the 3rd embodiment of the optical sensor of the passive resonant cavity of cascade with it, it comprises the active Fabry-Perot cavity 1 of launching pectination spontaneous emission spectrum uniformly-spaced or laser spectrum that has internal gain and has the uniformly-spaced passive Fabry-Perot cavity 4 of comb filtering spectrum, and optical power detector 3, passive Fabry-Perot cavity comprises: passive Fabry-Perot cavity first catoptron 42, passive Fabry-Perot cavity second catoptron 43, passive Fabry-Perot cavity passive waveguide region 40, the passive Fabry-Perot cavity sensing unit 41 that optical length can change with external environment.In addition, passive Fabry-Perot cavity can also be the passive resonant cavity that the inside multisection type active resonant cavity that has the distributed Feedback optical grating construction etc. is exported pectination spontaneous emission spectrum uniformly-spaced or laser spectrum.
Figure 10 the present invention is based on active resonant cavity and the 4th embodiment of the optical sensor of the passive resonant cavity of cascade with it, it comprises that an active Fabry-Perot cavity 1 with the output of pectination spectrum uniformly-spaced that has an internal gain and one have the uniformly-spaced passive annular resonant cavity 2 of comb filtering spectrum, and an optical power detector 3; Thereby active ring resonator is one have been applied the cycle microwave-driven signal 11 identical with the cycle of operation of photon in active resonant cavity and keeps its emission spectrum not to be subjected to the active Fabry-Perot cavity 1 of external interference.
By (5) formula as can be known, the luminous power that optical power detector 3 obtains is relevant with passive annular resonant cavity 2 optical path differences with active Fabry-Perot cavity 1, therefore the variation of any active Fabry-Perot cavity 1 light path also can cause the fluctuation of power, particularly be operated in the above multimode laser of threshold value because mode competition causes the instability of output spectrum and power, cause interference to measurement result, if but drive active Fabry-Perot cavity 1 with aforementioned microwave signal 11, its resonance frequency can be locked accurately so, thereby can reduce the interference that 1 pair of result of detection of active Fabry-Perot cavity causes, improve the sensitivity of sensing.
Figure 11 the present invention is based on active resonant cavity and the 5th embodiment of the optical sensor of the passive resonant cavity of cascade with it, it comprises that an active Fabry-Perot cavity 1 with the output of pectination spectrum uniformly-spaced that has an internal gain and one have the uniformly-spaced passive annular resonant cavity 2 of comb filtering spectrum, and an optical power detector 3; In addition, be provided with another optical power detector 6, be used to receive the output spectrum that does not pass through passive annular resonant cavity filtering in the outside of active Fabry-Perot cavity second catoptron 12.
Active Fabry-Perot cavity 1 output power when being subjected to the interference of external environment variation can fluctuate, particularly being operated in the above multimode laser of threshold value can have interference to measurement result because output spectrum that the mode competition effect causes and power are unstable, and the luminous power that optical power detector 6 obtains in the present embodiment can reflect this type of power swing, therefore, compare by the power that will obtain on optical power detector 3 and 6, the active resonant cavity power instability of can the filtering external interference bringing improves sensing accuracy.
Figure 12 the present invention is based on active resonant cavity and the 6th kind of embodiment of the optical sensor of the passive resonant cavity of cascade with it.Which comprises at least an active Fabry-Perot cavity 1 that has an internal gain and one and have the uniformly-spaced passive annular resonant cavity 2 of comb filtering spectrum with the output of pectination spectrum uniformly-spaced, and spectrometer 7; Active Fabry-Perot cavity is different with the optical length of passive annular resonant cavity, at least be provided with the passive annular resonant cavity sensing unit 21 that one section optical length can change with external environment in the passive annular resonant cavity, the spectrum of active Fabry-Perot cavity emission is input to passive annular resonant cavity by first passive wave guide 22, through after the filtering of passive annular resonant cavity, received by spectrometer 7 by second passive wave guide 23.
The light path of passive annular resonant cavity is slightly different with active Fabry-Perot cavity in the present embodiment, the mode of resonance frequency interval of two resonator cavitys is also different slightly, be respectively Δ f and Δ f, this makes that the mode of resonance of two resonator cavitys only overlaps fully at the fo place in laser material gain spectral scope, as Figure 13.At this moment, have only the luminous energy of frequency f o to pass through passive annular resonant cavity, thereby the intensity that can see fo on spectrometer is far longer than adjacent pattern than low-loss ground.When the light path of passive annular resonant cavity changes owing to the change of sensing unit (part in the frame of broken lines) equivalent refractive index, the filtering spectral line of passive annular resonant cavity can produce an overall offset, cause overlapping the peak and move, and the lowest common multiple of Δ f and Δ f becomes Free Spectral Range to adjacent harmonic peak.The relative optical power distribution of each harmonic peak changes, and utilizes an external spectrometer 7 just can measure variations in refractive index.Owing to utilized cursor effect, so this method has higher sensitivity than traditional single passive resonant ring.
It is 200 μ m that Figure 14 has provided a length, refractive index is 3.215, operation wavelength is 360 μ m at fluorescence emission spectrum and girth that the active Fabry-Perot cavity of 1550nm is operated in below the threshold current, the transmission spectrum of the passive annular resonant cavity that refractive index is identical with this active resonant cavity.At this moment, the mode of resonance of two resonator cavitys overlaps fully at the 1550nm place, the luminous energy that has only the 1550nm wavelength in the emission spectrum of active Fabry-Perot cavity by passive annular resonant cavity, can obtain spectrum as shown in figure 15 than low-loss ground from the spectrometer.
When the refractive index of passive resonant cavity because of the external environment influence when 3.215 become 3.2155, the fluorescence emission spectrum of active resonant cavity and the transmission spectrum of passive resonant cavity are as shown in figure 16, because moving of passive annular resonant cavity transmission spectrum, the mode of resonance of two resonator cavitys becomes at the 1548nm place and overlaps fully, have only the luminous energy of 1548nm wavelength to pass through passive annular resonant cavity, on spectrometer, obtain spectrum as shown in figure 17 than low-loss ground.
Can obtain by above-mentioned analysis, when the variations in refractive index 5 * 10 of passive annular resonant cavity
-4The time, a saltus step just takes place in the pattern of energy maximum in the output spectrum of this sensor, can simply converse the variable quantity of passive annular resonant cavity waveguide index, further be transformed into the variation (as temperature, humidity) of external environment with the number of moding.In addition, when change of refractive was between two states, we can come the resolution of further refinement refractive index by the power ratio (as Figure 18) between the suitable pattern of two energy in the output spectrum.
The foregoing description is used for the present invention that explains, rather than limits the invention.In the protection domain of spirit of the present invention and claim, any modification and change to the present invention makes all fall into protection scope of the present invention.For example active Fabry-Perot cavity can change makes other any active resonant cavities of launching pectination spontaneous emission spectrum uniformly-spaced or laser spectrum, and passive annular resonant cavity can change and does the optical texture that any other can produce the periodic filter spectral line, as etched diffraction grating, array waveguide grating, sampling Bragg grating etc.