CN112051696A - Miniaturized compression source generating device - Google Patents

Abstract

The invention relates to a miniaturized compressed source generating device, belonging to the technical field of continuous variable non-classical light field generating equipment, comprising a laser source, an optical isolation device, an optical resonant cavity and an optical reflection device; the laser output from the laser source passes through the optical isolation device Then, it is incident into the optical resonator, and after the parametric up-conversion occurs in the optical resonator, the generated frequency-doubling light is output from the optical resonator, reflected by the light reflection device, and returns to the optical resonator along the original path, and acts as a pump. The Pu light is parametrically down-converted with the nonlinear crystal in the optical resonator, and the generated fundamental frequency compressed light is emitted from the optical resonator, returns to the optical isolation device, and is output through the optical isolation device. The device of the present invention realizes the generation of high-quality compressed state optical field only through a single optical cavity without additional frequency doubling cavity under low-power laser injection, compact structure, easy adjustment, strong practicability, and easy productization and mass production , which can be applied to cutting-edge fields such as quantum precision measurement, biological measurement and quantum imaging.

Description

A miniaturized compressed source generating device

technical field

The invention belongs to the technical field of continuous variable non-classical light field generation, in particular to a miniaturized compression source generation device with compact structure and strong practicability.

Background technique

The continuous variable squeezed state light field is an important non-classical light field, which can reduce the quantum fluctuation of an observable physical quantity of the light field to below the standard quantum limit. One of the hottest research contents, it is widely used in many research fields such as gravitational wave detection, optical precision measurement, and quantum information science.

At present, parametric down-conversion is the most effective way to generate compressed light, and high-quality compressed light can be obtained based on this method, but this method requires a frequency-doubling cavity to generate frequency-doubling light, and pumping an optical parametric oscillator through the frequency-doubling light to obtain Squeezed light field. Due to the addition of the frequency doubling cavity, additional locking devices such as cavity length and phase are required, and the structure of the system is relatively complex; the compressed state light field can also be obtained by using parametric up-conversion. The advantage is that the compressed state of the shorter wavelength beam can be obtained, The simplicity of the device is beneficial to practical application, but the disadvantage is that the compression degree of the obtained compressed light is not high, which cannot meet the actual needs.

SUMMARY OF THE INVENTION

The invention overcomes the shortcomings of the prior art, and the technical problem to be solved is: to provide a miniaturized compressed source generating device, which can generate a high-quality compressed state through a single optical cavity without an additional frequency-doubling cavity under the injection of a low-power laser. light field.

In order to solve the above technical problems, the technical scheme adopted in the present invention is: a miniaturized compressed source generating device, including a laser source, an optical isolation device, an optical resonant cavity and a light reflection device; , incident into the optical resonator, after the parametric up-conversion occurs in the optical resonator, the generated frequency-doubled light is output from the optical resonator, reflected by the light reflective device, and then returned to the optical resonator along the original path, and used as a pump The light is parametrically down-converted with the nonlinear crystal in the optical resonator, and the generated fundamental frequency compressed light is emitted from the optical resonator, returns to the optical isolation device, and is output through the optical isolation device.

The optical isolation device is an optical isolator or an optical fiber circulator.

The optical resonant cavity includes a nonlinear crystal and a first cavity mirror, a second cavity mirror, a third cavity mirror and a fourth cavity mirror that form a four-mirror ring cavity, and the first cavity mirror and the second cavity mirror are plano-concave mirror, the third cavity mirror and the fourth cavity mirror are plane cavity mirrors, the first cavity mirror is an input and output coupling mirror, and its outer end surface is coated with double antireflection coatings for fundamental frequency light and frequency-doubling light, and the inner end surface can Frequency light and frequency doubled light are transmitted.

The reflectivity of the second cavity mirror, the third cavity mirror and the fourth cavity mirror to the fundamental frequency light and the frequency doubled light is greater than 99.9%, and both ends of the nonlinear crystal are coated with the fundamental frequency light and the frequency doubled light. Dual-band anti-reflection coating.

The transmittance of the inner end of the first cavity mirror to the fundamental frequency light is 10%, and the transmittance to the frequency doubled light is 20%.

One of the cavity mirrors of the optical resonant cavity is fixedly arranged on the first piezoelectric ceramic, and the first piezoelectric ceramic is used to adjust the cavity length of the optical resonant cavity.

The light reflecting device includes a dichroic mirror, a fundamental frequency light reflecting mirror and a frequency-doubling light reflecting mirror, and the frequency-doubling light reflecting mirror is fixedly arranged on the second piezoelectric ceramic, and the fundamental frequency light output from the optical resonant cavity The frequency-doubling light and the frequency-doubling light are separated by the dichroic mirror, and the separated base-frequency light and frequency-doubling light are reflected by the base-frequency light mirror and the frequency-doubling light mirror, respectively, and then return to the dichroic mirror, and then return to the optical resonator through the original path of the dichroic mirror. .

One side of the dichroic mirror close to the optical resonant cavity is anti-reflection for the frequency-doubling light, the fundamental frequency light is highly reflected, and the other side is anti-reflection for the frequency-doubling light.

The transmittance of the frequency-doubling light on one side of the dichroic mirror close to the optical resonant cavity is greater than 97%, the reflectivity of the fundamental frequency light is greater than 99.9%, and the reflectivity of the other side of the frequency-doubling light is less than 0.5%.

The laser source, optical isolation device, optical resonator and optical reflection device are fixed on a convenient moving optical vibration isolation platform.

Compared with the prior art, the present invention has the following beneficial effects: the present invention realizes parametric up-conversion and parametric down-conversion simultaneously in a single optical resonant cavity by feeding back the frequency-doubling light generated by parametric up-conversion, and only needs to inject low-power The fundamental frequency light can obtain the compressed light with high compression degree. Therefore, the present invention provides a miniaturized compressed source generating device, which can generate high-quality compressed state through a single optical cavity without additional frequency doubling cavity under low-power laser injection. light field. Experiments have confirmed that 5dB vacuum compression light can be obtained by injecting 25mW of fundamental frequency light. Moreover, the device does not need to lock the relative phases of the pump light and the seed light, but only needs to lock the cavity length of the optical resonator. The locking device is simple and the experimental system is easy to use. Adjustable and easy to operate. The compact structure, easy adjustment, strong practicability, easy productization and mass production, can be applied to frontier fields such as quantum precision measurement, biological measurement and quantum imaging.

Description of drawings

Fig. 1 is the principle block diagram of a kind of miniaturized compressed source generation device provided by the embodiment of the present invention;

2 is a schematic diagram of an optical path of a miniaturized compressed source generating device provided by an embodiment of the present invention;

Fig. 3 is the measurement result graph of the compressed state light field in the range of 0-10MHz that the analysis frequency that the present invention produces;

Fig. 4 is the measurement result graph of the compressed state light field of the compressed light generated in the embodiment of the present invention at the analysis frequency of 2MHz;

1—laser source, 2—optical isolation device, 3—optical resonant cavity, 4—light reflection device, 5—platform, 6—first polarization beam splitter prism, 7—Faraday rotator, 8—second polarization beam splitter prism , 9—first cavity mirror, 10—second cavity mirror, 11—third cavity mirror, 12—fourth cavity mirror, 13—fundamental frequency light, 14—frequency doubled light, 15—dichroic mirror, 16—fundamental frequency Light high mirror, 17 - frequency doubled light high mirror, 18 - compressed light.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not All the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work, all belong to the protection scope of the present invention.

As shown in FIG. 1, an embodiment of the present invention provides a miniaturized compressed source generating device, including: a laser source 1, an optical isolation device 2, an optical resonant cavity 3 and an optical reflection device 4, the laser 1 outputs laser light; the The optical isolation device 2 is used to output the compressed light generated by the optical resonant cavity; the optical resonant cavity 3 is used to generate a compressed state light field; the optical reflection device 4 reflects the fundamental frequency light 13 and the frequency doubled light 14 The optical resonator 3 generates a squeezed light field. In order to enable the system to stably output compressed light and be suitable for various application scenarios, the above components are fixed on a small vibration isolation platform 5 that is easy to move.

In this embodiment, the laser output from the laser source 1 is incident into the optical resonator 3 after passing through the optical isolation device 2 , and after the parametric up-conversion takes place in the optical resonator 3 , the generated frequency-doubled light is emitted from the optical resonator 3 . After the internal output, after being reflected by the light reflection device 4, it returns to the optical resonator 3 along the original path, and is used as a pump light to undergo parametric down-conversion with the nonlinear crystal in the optical resonator 3, and the generated fundamental frequency compressed light is transmitted from the optical resonator. After 3 is emitted, it returns to the optical isolation device 2 and is output through the optical isolation device 2 .

As shown in FIG. 2 , it is a schematic diagram of an optical path of a miniaturized compression source generating device provided in an embodiment of the present invention. Specifically, in this embodiment, the optical resonant cavity 3 includes a nonlinear crystal and a four-mirror ring cavity. The first cavity mirror 9, the second cavity mirror 10, the third cavity mirror 11 and the fourth cavity mirror 12, the first cavity mirror 9 and the second cavity mirror 10 are plano-concave mirrors, the third cavity mirror 11 and the fourth cavity mirror The cavity mirror 12 is a plane cavity mirror, and the first cavity mirror 9 is an input and output coupling mirror. Pass. Specifically, the transmittance of the inner end of the first cavity mirror 9 to the fundamental frequency light is 10%, and the transmittance to the frequency doubled light is 20%. In addition, the transmittance of the inner end face of the first cavity mirror 9 to the fundamental frequency light and the frequency doubled light can also be set as required, and it only needs to have transmittance. The reflectivity of the second cavity mirror 10 , the third cavity mirror 11 and the fourth cavity mirror 12 to the fundamental frequency light and the frequency doubled light is greater than 99.9%. The nonlinear crystal in the optical resonator 3 is a PPKTP crystal with a size of 1*2*10mm. Both sides of the crystal are coated with anti-reflection films of fundamental frequency light and frequency doubled light. The temperature of the PPKTP crystal is controlled by a commercial temperature controller at the phase. Matching point, the temperature control accuracy is 0.01 degrees Celsius.

One of the cavity mirrors of the optical resonant cavity 3 is fixedly arranged on the first piezoelectric ceramic, and the first piezoelectric ceramic is used to actively control the cavity length of the optical resonant cavity 3, that is, to lock the length of the optical resonant cavity 3. Cavity length. As shown in FIG. 2 , in this embodiment, the optical isolation device 2 is an optical isolator composed of two polarization beam splitting prisms and a Faraday rotator. In addition, the optical isolation device 2 can also be an optical fiber loop device.

Further, as shown in FIG. 2 , the light reflecting device 4 includes a dichroic mirror 15, a fundamental frequency light reflecting mirror 16 and a frequency-doubling light reflecting mirror 17, and the frequency-doubling light reflecting mirror 17 is fixedly arranged on the second piezoelectric mirror. On the ceramic, the fundamental frequency light and the frequency doubled light output from the optical resonator 3 are separated by the dichroic mirror 15, and the separated fundamental frequency light and the frequency doubled light are respectively passed through the fundamental frequency light reflector 16 and the frequency doubled light reflector. 17 returns to the dichroic mirror 15 after being reflected, and then returns to the optical resonant cavity 3 through the original path of the dichroic mirror 15 . One side of the dichroic mirror 15 close to the optical resonant cavity 3 is anti-reflection for the frequency-doubled light, the fundamental frequency light is highly reflected, and the other side is for the anti-reflection of the frequency-doubling light. One side of the dichroic mirror 15 close to the optical resonator 3 has a transmittance of more than 97% for the frequency-doubled light, the reflectivity of the fundamental frequency light is greater than 99.9%, and the reflectivity of the other side of the double-frequency light is less than 0.5%. Through the second piezoelectric ceramic, the relative phase between the pump light and the seed light, that is, the relative phase between the frequency-doubling light and the fundamental frequency compressed light, can be scanned, and the classical gain can be monitored by scanning the phase.

In this embodiment, the 1080 nm fundamental frequency light emitted from the laser source 1 passes through the optical isolation device 2 and is injected into the optical resonator 3, and the optical resonator 3 is locked by standard PDH frequency stabilization technology. After the cavity length, the optical resonant cavity 3 stably outputs 540 nm frequency-doubling light 14, the fundamental frequency light 13 reflected by the first cavity mirror 9 and the frequency-doubling light 14 output by the optical resonant cavity 3 are separated by the dichroic mirror 15, respectively by After the fundamental frequency light high-reflection mirror 16 and the frequency-doubling light high-reflection mirror 17 are reflected, return and pass through the dichroic mirror 15 and then enter the optical resonant cavity 3 to generate compressed light 18 , and the generated compressed light 18 is output by the first cavity mirror 9 , returns to the optical isolation device, and is output by the optical isolation device 2, and the compressed light can be detected by using a balanced zero-beat detection device.

As shown in FIG. 2, it is a schematic diagram of the optical path of a miniaturized compression source generating device provided by an embodiment of the present invention: the 1080 nm fundamental frequency light emitted by the laser 1 passes through the optical isolator 2 (used in this embodiment) The optical isolator is a combination of a polarizing beam splitter prism and a Faraday rotator), injected into the optical resonator 3, and after locking the cavity length of the optical resonator 3 by standard PDH frequency stabilization technology, the optical resonator Cavity 3 stably outputs 540nm frequency doubled light 14, the fundamental frequency light 13 reflected by the first cavity mirror 9 as the input and output mirror and the frequency doubled light 14 output by the optical resonator 3 are separated by the dichroic mirror 15, respectively The mirror 16 and the second high-reflection mirror 17 reflect, enter the optical resonant cavity 3 to generate compressed light 18, and the generated compressed light 18 is output by the optical isolator 2 and detected by a balanced zero-beat detection device.

As shown in FIG. 3 , which is the measurement result of the vacuum compressed state optical field generated in the embodiment of the present invention, the injection power in front of the optical resonator cavity is 25 mW, and the scanning frequency is 0-10 MHz. Among them, (a) is the inverse compression, (b) is the shot noise benchmark, (c) is the compression, and (d) is the electronic noise. The results show that we can prepare the compressed light in the range of 0-10MHz.

As shown in FIG. 4 , it is the measurement result of the vacuum compressed state optical field generated in the embodiment of the present invention. At this time, the injection power of the optical resonator is 25 mW, and the measured analysis frequency is 2 MHz. Among them, (a) represents the shot noise reference, and (b) represents the noise power curve of the compressed light with the local optical phase. The results show that the compression degree of the compressed light field is 5dB. The miniaturized compression source designed by the present invention obtains a stable output of compressed light under the condition of low injection power.

In the present invention, the frequency-doubling light output by the optical resonator is reflected back to the optical resonator to participate in the parametric down-conversion, and a single optical resonator is used to achieve the results that could only be achieved by two optical resonators in the past. volume, which helps to apply squeezed-state light fields to all aspects of real life.

It should be noted that, on the basis of the above-mentioned embodiments, the present invention can be implemented by adopting, but not limited to, lasers with wavelengths of 1550 nm, 1342 nm, 1064 nm and 795 nm as laser light sources.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (10)

1. A miniaturized compressed source generating device, characterized in that: it comprises a laser source (1), an optical isolation device (2), an optical resonant cavity (3) and a light reflection device (4); the laser source (1) outputs an output After the laser passes through the optical isolation device (2), it is incident into the optical resonator (3), and after parametric up-conversion occurs in the optical resonator (3), the generated frequency-doubled light is output from the optical resonator (3). , after being reflected by the light reflection device (4), it returns to the optical resonator (3) along the original path, and is used as a pump light to undergo parametric down-conversion with the nonlinear crystal in the optical resonator (3), and the generated fundamental frequency compressed light from After the optical resonant cavity (3) is emitted, it returns to the optical isolation device (2), and is output through the optical isolation device (2). 2 . The device for generating a miniaturized compressed source according to claim 1 , wherein the optical isolation device ( 2 ) is an optical isolator or an optical fiber circulator. 3 . 3. A miniaturized compressed source generating device according to claim 1, characterized in that, the optical resonant cavity (3) comprises a nonlinear crystal and a first cavity mirror (9), The second cavity mirror (10), the third cavity mirror (11) and the fourth cavity mirror (12), the first cavity mirror (9) and the second cavity mirror (10) are plano-concave mirrors, and the third cavity mirror ( 11) and the fourth cavity mirror (12) are plane cavity mirrors, the first cavity mirror (9) is an input and output coupling mirror, the outer end surface of which is coated with double antireflection coatings for fundamental frequency light and frequency doubling light, and the inner end surface can be The fundamental frequency light and the frequency doubled light are transmitted. 4 . The miniaturized compression source generating device according to claim 3 , wherein the second cavity mirror ( 10 ), the third cavity mirror ( 11 ) and the fourth cavity mirror ( 12 ) are responsive to the fundamental frequency. 5 . The reflectivity of light and frequency-doubling light is greater than 99.9%, and both ends of the non-linear crystal coating are coated with dual-band antireflection films of fundamental frequency light and frequency-doubling light. 5 . The miniaturized compression source generating device according to claim 3 , wherein the transmittance of the inner end of the first cavity mirror ( 9 ) to the fundamental frequency light is 10%, and the frequency doubling rate is 10%. 6 . The transmittance of light was 20%. 6 . The miniaturized compression source generating device according to claim 1 , wherein one cavity mirror of the optical resonant cavity ( 3 ) is fixedly arranged on the first piezoelectric ceramic, and the first piezoelectric ceramic is 6 . Piezoelectric ceramics are used to adjust the cavity length of the optical resonant cavity (3). 7. A miniaturized compressed source generating device according to claim 1, characterized in that the light reflecting device (4) comprises a dichroic mirror (15), a fundamental frequency light reflecting mirror (16) and a frequency-doubling light reflecting mirror (17), and the frequency-doubling light reflecting mirror (17) is fixedly arranged on the second piezoelectric ceramic, and the fundamental frequency light and frequency-doubling light output from the optical resonator (3) pass through the dichroic mirror (15) After separation, the separated fundamental frequency light and frequency doubled light are reflected by the fundamental frequency light reflector (16) and the frequency doubled light reflector (17) respectively, and then return to the dichroic mirror (15), and then pass through the original dichroic mirror (15). Then return to the optical resonator (3). 8 . The miniaturized compressed source generating device according to claim 1 , wherein the side of the dichroic mirror ( 15 ) close to the optical resonator ( 3 ) is anti-reflection for the frequency-doubled light, and the fundamental frequency light is high. 9 . On the contrary, the other side is anti-reflection of frequency doubled light. 9 . The miniaturized compressed source generating device according to claim 8 , wherein the transmittance of the side of the dichroic mirror ( 15 ) close to the optical resonator ( 3 ) to the frequency-doubled light is greater than 97%, 9 . The reflectivity of the fundamental frequency light is greater than 99.9%, and the reflectivity of the other side is less than 0.5% for the doubled frequency light. 10. A miniaturized compressed source generating device according to claim 1, characterized in that, the laser source (1), the optical isolation device (2), the optical resonant cavity (3) and the light reflection device (4) are fixed in a On the optical vibration isolation platform (5) that is easy to move.

Images