CN113140947A - Single-frequency continuous wave tunable titanium sapphire laser based on double-refraction etalon locking - Google Patents
Single-frequency continuous wave tunable titanium sapphire laser based on double-refraction etalon locking Download PDFInfo
- Publication number
- CN113140947A CN113140947A CN202110434548.7A CN202110434548A CN113140947A CN 113140947 A CN113140947 A CN 113140947A CN 202110434548 A CN202110434548 A CN 202110434548A CN 113140947 A CN113140947 A CN 113140947A
- Authority
- CN
- China
- Prior art keywords
- etalon
- birefringent
- laser
- light path
- titanium sapphire
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0071—Beam steering, e.g. whereby a mirror outside the cavity is present to change the beam direction
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0057—Temporal shaping, e.g. pulse compression, frequency chirping
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0085—Modulating the output, i.e. the laser beam is modulated outside the laser cavity
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/086—One or more reflectors having variable properties or positions for initial adjustment of the resonator
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
Abstract
The invention relates to a single-frequency continuous wave tunable titanium sapphire laser locked based on a birefringent etalon, which comprises a pumping source, a beam coupling system and a laser resonant cavity, wherein the beam coupling system is positioned on an emergent light path of the pumping source; a double-refraction etalon forming a certain included angle with the main light path is arranged in the laser resonant cavity; a plane reflector, a first lens, a quarter-wave plate and a polarization beam splitter are sequentially arranged on a reflection light path of the birefringent etalon; a second lens and a first photoelectric detector are arranged on a reflection light path of the polarization beam splitter; a third lens and a second photodetector are arranged on a transmission light path of the polarization beam splitter; the output ends of the first photoelectric detector and the second photoelectric detector are connected with a servo controller; the signal output end of the servo controller is connected with the galvanometer motor; the birefringent etalon is adhered to the rotating shaft of the galvanometer motor. The tunable titanium sapphire laser can avoid the influence of extra modulation signals on the noise characteristic of the laser, and realize the tunable titanium sapphire laser with low noise.
Description
Technical Field
The invention relates to the technical field of titanium sapphire lasers, in particular to a single-frequency continuous wave tunable titanium sapphire laser based on double-refraction etalon locking.
Background
The single-frequency continuous wave tunable titanium sapphire laser developed based on the titanium-doped sapphire crystal has the excellent characteristics of low intensity noise, high stability, good beam quality and the like, and the spectral range of output laser can cover transition absorption lines (red light and near infrared wave bands of 700nm-1000 nm) of alkali metal atoms such as potassium, rubidium, cesium and the like, so that the single-frequency continuous wave tunable titanium sapphire laser is widely applied to the scientific research fields of atom-based cold atom physics, quantum optics and the like. In these atomic-based research fields, it is often necessary to precisely adjust the output frequency of the laser to precisely match the atomic transition absorption line, which requires a certain frequency continuous tuning capability of the titanium sapphire laser. To achieve continuous tuning of a titanium-sapphire laser, it is often necessary to lock an etalon within the laser cavity to the laser cavity's oscillation mode in real time and continuously scan the cavity length of the cavity. The most common approach to locking etalons is based on a piezoelectric ceramic driven modulation locking approach. In this method, the implementation of etalon locking is: the slice etalon is adhered to a piezoelectric ceramic arranged on a support, the support is fixed on a rotating shaft of a galvanometer motor, the etalon generates micro-angle vibration by applying a modulation signal to the piezoelectric ceramic, a photoelectric detector is used for detecting a reflected light signal of the etalon and converting the reflected light signal into an electric signal, the electric signal is mixed with a local oscillation signal to generate an error signal, and the rotating shaft of the galvanometer motor is controlled to rotate to control the angle of the etalon. In the locking device, in order to obtain a better error signal, the frequency of an applied modulation signal needs to be fixed at the natural frequency of the piezoelectric ceramic, and the modulation signal increases the intensity noise of the laser at the corresponding frequency, so that the suppression of the intensity noise of the laser at the frequency section is influenced, and the application of the laser in the fields of precision measurement and the like is limited. In the method, an etalon inserted into a cavity is made of an electro-optical crystal material, a modulation signal is applied to the crystal in an electric field mode, an optical field in the cavity is modulated by using the electro-optical effect of the crystal, the modulation signal is detected by using a photoelectric detector and is mixed with a local oscillation signal to generate an error signal, and a rotating shaft of a rotary galvanometer motor is controlled to control the angle of the etalon so as to realize the locking of the etalon. In the locking mode, the electro-optic effect of the crystal is independent of the frequency of the modulation signal, so that the frequency of the modulation signal can be selected at will, and the control on the intensity noise of the laser can be realized by changing the frequency of the modulation signal. However, the presence of the modulation signal still introduces additional noise, which affects subsequent experimental systems. In addition to the method of modulating the locking etalon, the frequency continuous tuning of the titanium sapphire laser can be realized by introducing nonlinear loss in the resonant cavity and utilizing the suppression capability of the nonlinear loss on the secondary oscillation mode in the cavity. The method does not need a modulation locking etalon, so that the laser system is not influenced by a modulation signal, and the low-frequency band intensity noise of the laser is reduced to a certain extent under the action of nonlinear loss. However, due to the limitation of the acceptance bandwidth of the nonlinear crystal, the titanium sapphire laser can only realize the function in a specific frequency band and cannot cover the output spectral range of the titanium sapphire laser.
Disclosure of Invention
The invention aims to overcome the defects of the existing continuously tunable titanium sapphire laser, provides a single-frequency continuous wave tunable titanium sapphire laser locked based on a birefringent etalon, and can realize continuous tuning in a low-noise and wide-band range based on a modulation-free locking etalon method.
In order to achieve the purpose, the invention provides the following scheme:
a single-frequency continuous wave tunable titanium sapphire laser based on birefringent etalon locking comprises a pumping source 1, a beam coupling system 2 positioned on an emergent light path of the pumping source 1 and a laser resonant cavity 3 positioned on an emergent light path of the beam coupling system 2; a birefringent etalon 7 forming a certain included angle with the main optical path is arranged in the laser resonant cavity 3; a plane reflector 8, a first lens 9, a quarter-wave plate 10 and a polarization beam splitter 11 are sequentially arranged on a reflection light path of the birefringent etalon 7; a second lens 12 and a first photoelectric detector 13 are arranged on a reflection light path of the polarization beam splitter 11; a third lens 14 and a second photodetector 15 are arranged on a transmission light path of the polarization beam splitter 11; the output ends of the first photodetector 13 and the second photodetector 15 are connected to a servo controller 16; the signal output end of the servo controller 16 is connected with a galvanometer motor 17; the birefringent etalon 7 is bonded to the rotating shaft of the galvanometer motor 17.
Optionally, the laser resonant cavity 3 adopts a four-mirror ring laser resonant cavity structure.
Optionally, the laser resonator 3 includes a first plano-concave mirror 31, a second plano-concave mirror 32, a first plane mirror 33, and a second plane mirror 34; a gain medium titanium sapphire crystal 4 is arranged on a light path between the first planoconvex mirror 31 and the second planoconvex mirror 32, a birefringent filter 5 is arranged on a light path between the second planoconvex mirror 32 and the first planoconvex mirror 33, an optical isolator 6 is arranged on a light path between the first planoconvex mirror 31 and the second planoconvex mirror 34, and piezoelectric ceramics 18 are bonded on the first planoconvex mirror 33.
Optionally, the birefringent etalon 7 is a thin birefringent crystal which is cut along an optical axis direction, i.e., a z direction, and processed into two light-passing surfaces, i.e., x-o-z surfaces, which are parallel, and an included angle between a polarization direction of incident light of the birefringent etalon 7 and an x axis of the crystal is 2 to 3 degrees.
Optionally, the focus of the first lens 9 is set at the reflection point of the birefringent etalon 7; the focal point of the second lens 12 is set on the effective receiving surface of the first photodetector 13; the focal point of the third lens 14 is set on the effective receiving surface of the second photodetector 15.
Optionally, the servo controller 16 includes an addition-subtraction circuit, a division circuit, and a PI control circuit.
Optionally, the birefringent crystal is a lithium niobate crystal, a lithium tantalate crystal, or a quartz crystal.
Optionally, the pumping source 1 is a 532nm all-solid-state continuous wave laser, a 520nm semiconductor laser diode, or a 450nm semiconductor laser diode.
Optionally, the pumping mode of the pump source 1 is end-face pumping.
Optionally, the gain medium titanium sapphire crystal 4 is an optical crystal processed with two parallel light-passing surfaces or an optical crystal placed in the light path at the brewster angle.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention obtains the low-noise single-frequency continuous wave tunable titanium sapphire laser which has simple structure, can stably run and can realize continuous tuning in a wide band tunable range by adopting the double-refraction etalon.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic structural diagram of a single-frequency continuous wave tunable titanium sapphire laser based on birefringent etalon locking provided by the present invention;
FIG. 2 is a schematic diagram showing the crystal cutting method and the polarization direction of incident light of the birefringent etalon in the single-frequency continuous wave tunable Titania laser according to the present invention;
FIG. 3 shows the results of a single-frequency continuous wave tunable titanium sapphire laser tuned continuously around 780 nm;
description of the symbols:
1-pumping source, 2-light beam coupling system, 3-laser resonant cavity, 4-gain medium titanium gem crystal, 5-birefringent filter, 6-broadband optical isolator, 7-birefringent etalon, 8-plane reflector, 9-first lens, 10-quarter wave plate, 11-polarization beam splitter, 12-second lens, 13-first photoelectric detector, 14-third lens, 15-second photoelectric detector, 16-servo controller, 17-galvanometer motor, 18-piezoelectric ceramic, 31-first plano-concave mirror, 32-second plano-concave mirror, 33-first plano-mirror, 34-second plano-mirror, 61-magneto-optically active crystal, 62-natural optically active crystal, 71-polarization direction of incident light beam, 72-reflected light from the birefringent etalon, 73-incident light beam propagation direction, 74-crystal z-axis direction, 75-crystal x-axis direction, 76-crystal y-axis direction, 77-minor polarization component, 78-included angle, 79-major polarization component.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention aims to provide a single-frequency continuous wave tunable titanium sapphire laser based on double-refraction etalon locking, which can realize continuous tuning in a low-noise and wide-band range based on a modulation-free locking etalon method.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic structural diagram of a single-frequency continuous wave tunable titanium sapphire laser locked by a birefringent etalon, as shown in fig. 1, the single-frequency continuous wave tunable titanium sapphire laser includes a pump source 1, a beam coupling system 2, a laser resonant cavity 3, a gain medium titanium sapphire crystal 4, a birefringent filter 5, a broadband optical isolator 6, a birefringent etalon 7, a plane mirror 8, a first lens 9, a quarter-wave plate 10, a polarization beam splitter 11, a second lens 12, a first photodetector 13, a third lens 14, a second photodetector 15, a servo controller 16, a galvanometer motor 17, and a piezoelectric ceramic 18.
The light beam coupling system 2 is positioned on an emergent light path of the pumping source 1; the laser resonant cavity 3 is arranged on an emergent light path of the light beam coupling system 2, and a pumping light beam output by the pumping source 1 is incident to the center of a gain medium titanium sapphire crystal 4 in the laser resonant cavity 3 after being shaped and focused by the coupling system 2.
The laser resonant cavity 3 adopts a four-mirror annular laser resonant cavity structure; the laser resonant cavity 3 comprises a first plano-concave mirror 31, a second plano-concave mirror 32, a first plano-mirror 33 and a second plano-mirror 34, a gain medium titanium sapphire crystal 4 is arranged between the first plano-concave mirror 31 and the second plano-concave mirror 32, a birefringent filter 5 and an optical isolator 6 are simultaneously arranged in the four-mirror annular laser resonant cavity 3, piezoelectric ceramics 18 are bonded on the first plano-mirror 33, wherein the cavity length of the laser resonant cavity 3 can be changed by changing the voltage of the piezoelectric ceramics 18, and the continuous tuning of the laser frequency is realized.
A double-refraction etalon 7 forming a certain included angle with the main optical path is further arranged in the laser resonant cavity 3, a reflected light beam of the double-refraction etalon 7 is separated from the main optical path, and a plane reflector 8, a first lens 9, a quarter-wave plate 10 and a polarization beam splitter 11 are arranged on a reflected light path of the double-refraction etalon 7; the reflection light path of the polarization beam splitter 11 is provided with a second lens 12 and a first photoelectric detector 13; a third lens 14 and a second photoelectric detector 15 are arranged on a transmission light path of the polarization beam splitter 11; the output ends of the first photoelectric detector 13 and the second photoelectric detector 15 are connected to a servo controller 16, the signal output end of the servo controller 16 is connected to a galvanometer motor 17, and the birefringent etalon 7 is bonded to a rotating shaft of the galvanometer motor 17.
After the reflected light beam of the birefringent etalon 7 is detected, the reflected light beam is extracted by the servo controller 16 and generates a control signal to act on the mirror motor 17 to control the angle of the birefringent etalon 7, and further the transmission peak of the birefringent etalon 7 is locked at the oscillation frequency of the resonant cavity in real time.
Two end faces of the gain medium titanium gem crystal 4 are cut by Brewster angles (60.4), and a c axis is vertical to a light passing direction in the crystal, so that pi polarized pump light and oscillation light are transmitted almost without loss, and sigma polarized light is automatically inhibited; the birefringent filter 5 is made of three quartz crystal materials with parallel optical axes and a thickness ratio of 1:4:16, and is arranged in the resonant cavity at the Brewster angle; the broadband optical isolator 6 is composed of a magnetic rotation crystal 61 and a natural rotation crystal 62 of an external magnetic field, and both are placed in the laser resonant cavity at a Brewster incidence angle, and the broadband optical isolator 6 forces the low-noise single-frequency continuous wave tunable titanium sapphire laser locked based on the inner cavity double refraction etalon to operate unidirectionally.
Specifically, according to the birefringence characteristic and the etalon reflection characteristic of the birefringence etalon 7, when the laser oscillation frequency is matched with the transmission peak of the birefringence etalon 7, the reflected light beam of the birefringence etalon 7 has different polarization states, the polarization state of the reflected light beam of the birefringence etalon 7 is detected by using the combination of the quarter-wave plate 10, the polarization beam splitter 11, the first photoelectric detector 13 and the second photoelectric detector 15, so that the deviation value between the transmission peak of the birefringence etalon 7 and the laser oscillation frequency can be effectively extracted for feedback locking of the birefringence etalon 7, and a modulation and demodulation technology is not needed, thereby effectively avoiding the influence of an extra modulation signal on the intensity noise of the laser and realizing the low-noise tunable titanium-sapphire laser.
Specifically, the focal point of the first lens 9 is set at the reflection point of the birefringent etalon 7, and the focal points of the second lens 12 and the third lens 14 are set on the effective receiving surfaces of the first photodetector 13 and the second photodetector 15, respectively, so as to ensure that when the birefringent etalon 7 rotates around the rotation axis of the motor, the reflected light beam of the birefringent etalon 7 is always within the effective transmission range of the quarter-wave plate 10 and the polarization beam splitter 11, and can be always effectively detected by the first photodetector 13 and the second photodetector 15.
Specifically, the servo controller 16 includes an addition/subtraction circuit, a division circuit, and a PI control circuit, and is configured to extract a deviation signal between the transmission peak of the birefringent etalon 7 and the laser oscillation frequency and generate a corresponding control signal.
For the device in fig. 1, the present invention further provides a method for realizing the locking of the birefringent etalon 7 and the continuous tuning of the laser output wavelength based on the above embodiment, including the following steps:
(1) the pumping light emitted by the pumping source 1 is coupled into the center of a gain medium titanium gem crystal 4 in a laser resonant cavity 3 through a light beam coupling system 2, the pumping generates laser, and a small part of the laser reflected by an intracavity birefringent etalon 7 is divided into reflected light and transmitted light after sequentially passing through a plane mirror 8, a first lens 9, a quarter wave plate 10 and a polarization beam splitter 11;
(2) the reflected beam enters the first photoelectric detector 13 to be converted into an electric signal after being focused by the second lens 12, and the transmitted beam enters the second photoelectric detector 15 to be converted into an electric signal after being focused by the third lens 14;
(3) the output signals of the first photodetector 13 and the second photodetector 15 enter the servo controller 16 to perform addition, subtraction and division operations, respectively, and then the deviation value between the transmission peak of the birefringent etalon 7 and the laser oscillation frequency, that is, the deviation value is extracted
I1And I2Output signals of the first photodetector 13 and the second photodetector 15, respectively, where error is a deviation value;
(4) the extracted deviation value is used as a control signal to act on a galvanometer motor 17 to control the angle of the birefringent etalon 7, so that the real-time locking of the birefringent etalon 7 is realized;
(5) continuous tuning of the laser frequency is achieved by varying the cavity length of the laser cavity 3 by scanning the length of the piezoelectric ceramic 18.
Fig. 2 is a schematic diagram of a crystal cutting method and an incident light polarization direction of a birefringent etalon in a single-frequency continuous wave tunable titanium sapphire laser according to the present invention, as shown in fig. 2, the birefringent etalon 7 is cut along a crystal optical axis direction 74 (crystal z-axis direction), an incident light beam propagation direction 73 is propagated along a crystal y-axis direction, and a small angle included angle 78 of 2-3 ° is formed between a polarization direction 71 of the incident light beam and a crystal x-axis direction 75. An incident light beam is decomposed into a main polarization component 79 along the x-axis direction 75 of the crystal and a sub polarization component 77 along the z-axis direction 74 of the crystal, the refractive indexes of the two polarization components in the crystal are different according to the birefringence characteristics of the crystal, and then according to the reflection characteristics of the etalon, when the wavelength or frequency of the light of the main polarization component 79 is matched with the resonant frequency of the birefringent etalon 7, the polarization state of the reflected light 72 of the birefringent etalon 7 is different, and a deviation value between the transmission peak of the birefringent etalon 7 and the laser oscillation frequency can be extracted by detecting the change of the polarization state of the reflected light 72 of the birefringent etalon 7 for locking the birefringent etalon 7.
After the laser normally runs, the angle of the laser is adjusted along the normal direction of the birefringent filter 5 to realize coarse frequency tuning of the laser, then the incidence angle of the fine tuning element birefringent etalon 7 is rotated to realize fine frequency tuning of the laser, and finally the cavity length of the laser resonant cavity 3 is continuously changed by locking the birefringent etalon 7 and scanning the length of the piezoelectric ceramic 18 connected with the cavity mirror, so that the continuous frequency tuning of the laser is realized. Adjusting the birefringent filter 5 to make the output wavelength of the laser close to 780.2 nm; rotating the angle of the birefringent etalon 7 to make the laser output wavelength be about 780.210nm and locking the transmission peak of the birefringent etalon 7 at the laser oscillation frequency in real time; the length of the piezoelectric ceramic 18 is scanned to obtain the results of the continuous tuning experiment shown in figure 3. Under the combined action of the coarse tuning element birefringent filter 5, the fine tuning element birefringent etalon 7 and the fine tuning element piezoelectric ceramic 18, the titanium sapphire laser realizes frequency continuous tuning.
The present invention utilizes the birefringence effect of a birefringent crystal in combination with the reflective properties of an etalon. When a beam of linearly polarized light with a polarization direction forming a small angle (2-3 degrees) with the crystal main axis enters the birefringent etalon, the linearly polarized light is decomposed into two components which are parallel to the crystal main axis and perpendicular to the crystal main axis, wherein the component which is parallel to the crystal main axis is a main component, and the component which is perpendicular to the crystal main axis is a micro-sub component. The phase delay after one round of round trip in the crystal is different due to the difference in refractive index experienced by the two components, according to the standardThe reflective properties of the etalon, the reflected beam of the birefringent etalon exhibits different polarization states. When the principal component is matched with the resonance frequency of the etalon, namely the phase delay of the principal component is integral multiple of 2 pi after the principal component is transmitted back and forth in the etalon for one circle, the reflected light beam of the etalon is linearly polarized along the direction of the secondary component, and when the principal component is not matched with the resonance frequency of the etalon, the reflected light beam is elliptically polarized with different rotation degrees. The reflected beam of this different polarization state can be identified by a combination of a quarter-wave plate whose optical axis is at an angle of 45 ° to the principal axis of the birefringent etalon and a polarizing beam splitter whose optical axis is parallel to the principal axis of the birefringent etalon. The reflected light and transmitted light of the polarization beam splitter are converted into electric signals after passing through a photoelectric detector respectively, and then the two electric signals are subjected to difference, summation and division respectively, namely
The deviation value between the transmission peak of the etalon and the laser oscillation frequency can be extracted, and then the angle of the etalon is controlled by controlling the rotating shaft of the mirror vibrating motor, so that the transmission peak of the etalon is locked at the oscillation frequency of the laser in real time.
Compared with the prior art, the invention also discloses the following technical effects:
1. an etalon made of birefringent crystals is used as an intracavity mode selection element, an error signal is extracted by detecting the polarization state change of reflected light of the etalon based on the crystal birefringence effect and is used for locking the etalon, and a modulation and demodulation technology is not needed, so that the locking system is simplified in structure, simple in design and easier to realize.
2. Extra low-frequency modulation signals do not need to be introduced into the etalon locking system, so that the influence of the modulation signals on the noise of the laser is effectively avoided, and the low-noise single-frequency continuous wave broadband tunable titanium sapphire laser is realized.
3. The invention relates to a modulation-free locking method of a birefringent etalon, which is suitable for all-solid-state single-frequency continuous wave tunable lasers with any cavity structures.
4. The invention utilizes the birefringence effect of the crystal, extracts the error signal for locking the etalon by detecting the polarization state change of the reflected light of the birefringence etalon, does not need to introduce an additional modulation signal, effectively avoids the influence of the additional modulation signal on the noise characteristic of the laser, and realizes the tunable titanium sapphire laser with low noise.
In a word, the low-noise single-frequency continuous wave tunable titanium sapphire laser which is simple in structure, can stably run and can realize continuous tuning in a wide-band tunable range is obtained by adopting the birefringent etalon.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. A single-frequency continuous wave tunable titanium sapphire laser based on birefringent etalon locking is characterized by comprising a pumping source (1), a beam coupling system (2) located on an emergent light path of the pumping source (1) and a laser resonant cavity (3) located on an emergent light path of the beam coupling system (2); a birefringent etalon (7) forming a certain included angle with the main light path is arranged in the laser resonant cavity (3); a plane reflector (8), a first lens (9), a quarter-wave plate (10) and a polarization beam splitter (11) are sequentially arranged on a reflection light path of the birefringent etalon (7); a second lens (12) and a first photoelectric detector (13) are arranged on a reflection light path of the polarization beam splitter (11); a third lens (14) and a second photoelectric detector (15) are arranged on a transmission light path of the polarization beam splitter (11); the output ends of the first photoelectric detector (13) and the second photoelectric detector (15) are connected to a servo controller (16); the signal output end of the servo controller (16) is connected with a galvanometer motor (17); the birefringent etalon (7) is bonded on a rotating shaft of the galvanometer motor (17).
2. The single-frequency continuous wave tunable titanium sapphire laser based on birefringent etalon locking according to claim 1, wherein the laser resonator (3) adopts a four-mirror ring laser resonator structure.
3. A single-frequency continuous wave tunable titanium sapphire laser based on birefringent etalon locking according to claim 1 or 2, wherein the laser resonator (3) comprises a first plano-concave mirror (31), a second plano-concave mirror (32), a first plano-mirror (33) and a second plano-mirror (34); a gain medium titanium sapphire crystal (4) is arranged on a light path between the first plano-concave mirror (31) and the second plano-concave mirror (32), a birefringent filter (5) is arranged on a light path between the second plano-concave mirror (32) and the first plano-concave mirror (33), an optical isolator (6) is arranged on a light path between the first plano-concave mirror (31) and the second plano-concave mirror (34), and piezoelectric ceramics (18) are bonded on the first plano-concave mirror (33).
4. The single-frequency continuous wave tunable titanium sapphire laser locked by the birefringent etalon according to claim 1, wherein the birefringent etalon (7) is a thin birefringent crystal cut along an optical axis direction (z direction) and processed into two light-passing surfaces (x-o-z surfaces) in parallel, and an included angle between the polarization direction of incident light of the birefringent etalon (7) and the x axis of the crystal is 2-3 °.
5. A single-frequency continuous wave tunable titanium sapphire laser based on birefringent etalon locking according to claim 1, wherein the focus of the first lens (9) is set at the reflection point of the birefringent etalon (7); the focal point of the second lens (12) is set on the effective receiving surface of the first photodetector (13); the focal point of the third lens (14) is set on the effective receiving surface of the second photodetector (15).
6. The birefringent etalon locking based single frequency continuous wave tunable titanium sapphire laser of claim 1, wherein the servo controller (16) comprises an addition and subtraction circuit, a division circuit, and a PI control circuit.
7. The single-frequency continuous wave tunable titanium-sapphire laser based on birefringent etalon locking according to claim 4, wherein the birefringent crystal is a lithium niobate crystal, a lithium tantalate crystal, or a quartz crystal.
8. The single frequency continuous wave tunable titanium sapphire laser based on birefringent etalon locking according to claim 1, wherein the pump source (1) is a 532nm all-solid-state continuous wave laser, a 520nm semiconductor laser diode or a 450nm semiconductor laser diode.
9. The single-frequency continuous wave tunable titanium sapphire laser based on birefringent etalon locking according to claim 1, wherein the pumping mode of the pump source (1) is end-pumped.
10. The single-frequency continuous wave tunable titanium sapphire laser based on birefringent etalon locking according to claim 3, wherein the gain medium titanium sapphire crystal (4) is an optical crystal processed with two parallel light-passing surfaces or an optical crystal placed in the light path at Brewster's angle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110434548.7A CN113140947B (en) | 2021-04-22 | 2021-04-22 | Single-frequency continuous wave tunable titanium sapphire laser based on double-refraction etalon locking |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110434548.7A CN113140947B (en) | 2021-04-22 | 2021-04-22 | Single-frequency continuous wave tunable titanium sapphire laser based on double-refraction etalon locking |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113140947A true CN113140947A (en) | 2021-07-20 |
| CN113140947B CN113140947B (en) | 2022-08-23 |
Family
ID=76813273
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110434548.7A Active CN113140947B (en) | 2021-04-22 | 2021-04-22 | Single-frequency continuous wave tunable titanium sapphire laser based on double-refraction etalon locking |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113140947B (en) |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1601071A1 (en) * | 2004-05-25 | 2005-11-30 | Fujitsu Limited | Wavelength tunable laser device |
| US20060280219A1 (en) * | 2004-07-30 | 2006-12-14 | Shchegrov Andrei V | Frequency stabilized vertical extended cavity surface emitting lasers |
| CN101814694A (en) * | 2010-04-28 | 2010-08-25 | 天津奇谱光电技术有限公司 | tunable laser |
| CN101958505A (en) * | 2010-07-31 | 2011-01-26 | 山西大学 | Frequency locking device for dual wavelength external cavity resonance system |
| CN102136670A (en) * | 2011-01-27 | 2011-07-27 | 山西大学 | Double-end end-pumped solid laser based on polarization coupling |
| CN102916335A (en) * | 2012-10-22 | 2013-02-06 | 西安理工大学 | Pound-Drever-Hall frequency stabilizing system of dual-cavity dual-frequency solid laser device |
| US20140270618A1 (en) * | 2013-03-15 | 2014-09-18 | Gigoptix, Inc. | Wavelength tunable integrated optical subassembly based on polymer technology |
| CN106340798A (en) * | 2016-10-26 | 2017-01-18 | 山西大学 | Continuous tunable single-frequency ti sapphire laser based on locking of electro-optical etalon of internal cavity |
| CN107579413A (en) * | 2017-09-21 | 2018-01-12 | 山西大学 | A kind of method for extending all-solid-state continuous wave single-frequency laser tuning range |
| CN112290359A (en) * | 2020-10-28 | 2021-01-29 | 山西大学 | Double-resonant-cavity Raman laser |
-
2021
- 2021-04-22 CN CN202110434548.7A patent/CN113140947B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1601071A1 (en) * | 2004-05-25 | 2005-11-30 | Fujitsu Limited | Wavelength tunable laser device |
| US20060280219A1 (en) * | 2004-07-30 | 2006-12-14 | Shchegrov Andrei V | Frequency stabilized vertical extended cavity surface emitting lasers |
| CN101814694A (en) * | 2010-04-28 | 2010-08-25 | 天津奇谱光电技术有限公司 | tunable laser |
| CN101958505A (en) * | 2010-07-31 | 2011-01-26 | 山西大学 | Frequency locking device for dual wavelength external cavity resonance system |
| CN102136670A (en) * | 2011-01-27 | 2011-07-27 | 山西大学 | Double-end end-pumped solid laser based on polarization coupling |
| CN102916335A (en) * | 2012-10-22 | 2013-02-06 | 西安理工大学 | Pound-Drever-Hall frequency stabilizing system of dual-cavity dual-frequency solid laser device |
| US20140270618A1 (en) * | 2013-03-15 | 2014-09-18 | Gigoptix, Inc. | Wavelength tunable integrated optical subassembly based on polymer technology |
| CN106340798A (en) * | 2016-10-26 | 2017-01-18 | 山西大学 | Continuous tunable single-frequency ti sapphire laser based on locking of electro-optical etalon of internal cavity |
| CN107579413A (en) * | 2017-09-21 | 2018-01-12 | 山西大学 | A kind of method for extending all-solid-state continuous wave single-frequency laser tuning range |
| CN112290359A (en) * | 2020-10-28 | 2021-01-29 | 山西大学 | Double-resonant-cavity Raman laser |
Non-Patent Citations (2)
| Title |
|---|
| PIXIAN JIN 等: "Single-frequency CW Ti:sapphire laser with intensity noise manipulation and continuous frequency-tuning", 《OPTICS LETTERS》 * |
| 陈忆兰 等: "单频２ｍ波段全固态脉冲激光器技术进展", 《激光与光电子学进展》 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113140947B (en) | 2022-08-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10326250B2 (en) | Method for expanding tuning range of all-solid-state continuous-wave single frequency laser | |
| US5195104A (en) | Internally stimulated optical parametric oscillator/laser | |
| US8831056B2 (en) | Compact optical atomic clocks and applications based on parametric nonlinear optical mixing in whispering gallery mode optical resonators | |
| US6763042B2 (en) | Apparatus and method for frequency conversion and mixing of laser light | |
| CN106340798B (en) | Continuously adjustable single-frequency ti sapphire laser based on inner cavity electric light etalon lock | |
| CN104218444B (en) | Continuously adjustable single-frequency ti sapphire laser | |
| US5060233A (en) | Miniature blue-green laser source using second-harmonic generation | |
| JP2000261081A (en) | Laser | |
| US5079445A (en) | High output coupling cavity design for optical parametric oscillators | |
| JP6853780B2 (en) | Resonant microchip resonator-based system for generating laser beams through non-linear effects | |
| US6295160B1 (en) | Broad tuning-range optical parametric oscillator | |
| US4189652A (en) | Beam splitter coupled CDSE optical parametric oscillator | |
| US5142548A (en) | Broadband tuning and laser line narrowing utilizing birefringent laser hosts | |
| US3739295A (en) | Laser with means for suppressing back-ground fluorescence in the output | |
| US7035297B1 (en) | Continuous wave sodium beacon excitation source | |
| EP0654876B1 (en) | Birefrigence-compensated alignment-insensitive frequency doubler | |
| US3666349A (en) | Optical resonator having acousto-optic output coupling means | |
| US3928814A (en) | Collinear acousto-optical tunable filter and acousto-optically tunable laser | |
| CN113140947B (en) | Single-frequency continuous wave tunable titanium sapphire laser based on double-refraction etalon locking | |
| JPH08204275A (en) | Oscillation frequency stabilizing device and laser device | |
| US20050036534A1 (en) | External cavity tunable laser with provisions for intracavity optical reflection suppression | |
| US5222094A (en) | Ring laser | |
| EP3830642B1 (en) | Birefringent prism for wavelength separation | |
| CN112803224A (en) | Mid-infrared band difference frequency laser based on gallium-lanthanum niobate crystal | |
| KR100366699B1 (en) | Apparatus for generating second harmonic having internal resonance type |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20230519 Address after: 030006 No. C618, 6th floor, No. 402, South Central Street, Taiyuan Xuefu Park, Shanxi comprehensive reform demonstration zone, Taiyuan City, Shanxi Province Patentee after: TAIYUAN SHANDA YUGUANG TECHNOLOGICAL Co.,Ltd. Address before: Shanxi University, No.92 Wucheng Road, Xiaodian District, Taiyuan City, Shanxi Province Patentee before: SHANXI University |