Light source device and method for broadband fast wavelength tuning

Abstract

The invention provides a wide-band fast wavelength tuning light source device and method, and belongs to the field of laser technologies and precise spectrums.The wide-band fast wavelength tuning light source device comprises a first laser source and a second laser source, the first laser source generates first coherent light, the first coherent light is coupled into an annular resonant cavity, and the second laser source generates second coherent light; the first laser source generates first coherent light, optical parametric conversion is achieved at the first nonlinear crystal, idle light and signal light are output, the second laser source generates second coherent light, and the second coherent light is coupled into the annular resonant cavity from the other port. First coherent light and second coherent light which are left after optical parametric conversion at the first nonlinear crystal are coaxially injected into a second nonlinear medium, so that stimulated Raman intensity amplification and phase change of the first coherent light are realized; the intensity of the second coherent light injected into the second nonlinear medium is regulated and controlled, so that the three-wave phase matching condition in the resonant cavity can be quickly regulated and controlled, rapid and broadband wavelength tuning of signal light and idle light is realized, and the technical blank of broadband rapid wavelength tuning is filled.

Description

Technical Field

[0001] The invention belongs to the field of laser technology and precision spectroscopy technology, and in particular relates to a light source device and method for fast wavelength tuning with a wide spectrum band. Background Art

[0002] The present invention relates to laser technology, in particular to tunable laser technology used in the fields of spectral analysis, atomic cooling, etc. In these applications, the tunability of the laser is crucial. Taking spectral imaging as an example, the laser needs to have both a large wavelength tuning bandwidth and a high tuning speed to meet the requirements of high resolution and real-time fingerprint spectral imaging.

[0003] There are many types of broadband tunable lasers on the market, mainly including Ti:Sapphire lasers, temperature-tuned and pump-tuned optical parametric oscillators. Ti:Sapphire lasers have a basically fixed maximum tuning range of 700nm to 930nm. Wavelength tuning mainly relies on a rotatable birefringent filter or etalon built into the resonant cavity. The main problem with this type of mechanical tuning is the limited tuning speed, which is about 10nm / min. In addition, since the gain curve of the gain medium is not uniformly distributed or symmetrically distributed, mode hopping and non-uniform changes in the wavelength tuning step are very likely to occur during the tuning process. Optical parametric oscillators can simultaneously generate two coherent light beams (signal light and idle light) through a nonlinear parametric process. The wavelength of the output beam and its tuning characteristics are mainly determined by the wavelength of the pump light, the parametric gain curve determined by the phase matching conditions, etc., so they can be freely selected or adjusted. The advantage of the temperature-tuned optical parametric oscillator is that the output signal light and idle light can be tuned at the same time (the absolute value of their frequency changes is equal and the signs are opposite), and the tuning range is relatively wide. Taking a single resonant optical parametric oscillator based on periodically poled lithium niobate with a polarization period of 30.2μm pumped by a 1064nm laser as an example, when the crystal temperature changes from 120℃ to 190℃, the tuning ranges of the signal light and the idle light are 1604.2349nm~1653.3256nm and 3159.5625nm~2985.0026nm respectively. The main problem with temperature-tuned optical parametric oscillators is that the tuning range that can be achieved with a single polarization period is limited. When used for spectral measurement, it is usually necessary to move the crystal to replace the polarization period to expand the wavelength tuning range. More importantly, the temperature tuning speed is also slow, usually only 6~120nm / min. Pump-tuned optical parametric oscillators are generally single-resonant, that is, the wavelength of the signal light remains unchanged, and the output idle light wavelength changes accordingly to the change of the pump light wavelength. The main advantages of this type of light source are that the tuning system is simple and easy to operate, and the tuning speed is fast (consistent with the pump light tuning speed). The main problem is that only the idle light is tunable, and the tuning range is completely dependent on the tuning performance of the pump light, which is generally relatively narrow.

[0004] Existing tunable lasers either have a wider tuning bandwidth or a higher tuning speed, but no light source having both of the above characteristics has been reported or commercialized. Summary of the invention

[0005] The purpose of the present invention is to provide a light source device and method for broadband fast wavelength tuning to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a wide-band fast wavelength tunable light source device, comprising a first laser source and a second laser source, wherein the first laser source generates a first coherent light, which is coupled into a ring resonator, realizes optical parameter conversion at a first nonlinear crystal and outputs idle light and signal light, and the second laser source generates a second coherent light, which is coupled into the ring resonator from another port and is coaxially injected into a second nonlinear medium with the first coherent light.

[0007] Preferably, the second laser source is a continuously tunable laser, and the difference between the operating frequency of the generated second coherent light and the operating frequency of the first coherent light is equal to the intrinsic Raman frequency shift corresponding to the strongest Raman mode of the second nonlinear medium.

[0008] Preferably, the ring resonator includes a first cavity mirror, a first nonlinear crystal, a second cavity mirror, a third cavity mirror, a second nonlinear medium, and a fourth cavity mirror. The first cavity mirror is arranged on the right side of the first laser source, the first nonlinear crystal is arranged on the right side of the first cavity mirror, and the second cavity mirror is arranged on the right side of the first nonlinear crystal. The first coherent light is coupled by the first cavity mirror and injected into the first nonlinear crystal to realize optical parameter conversion, and the idle light is output through the second cavity mirror, and the signal light is output through the fourth cavity mirror. The third cavity mirror is arranged on the right side of the second laser source, the second nonlinear medium is arranged on the right side of the third cavity mirror, and the fourth cavity mirror is arranged on the right side of the second nonlinear medium. The second coherent light is coupled by the third cavity mirror and coaxially injected into the second nonlinear medium with the first coherent light circulating in the resonant cavity, and the phase of the first coherent light after passing through the second nonlinear medium changes with the intensity of the injected second coherent light.

[0009] Preferably, the first nonlinear crystal adopts a nonlinear crystal, such as lithium triborate, periodically poled lithium niobate, or periodically poled potassium titanyl phosphate with angle / temperature phase matching, and the second nonlinear medium is a nonlinear medium with strong Raman activity, specifically methane or sulfur hexafluoride gas placed in a sealed gas pool, or organic liquids such as benzene, carbon disulfide, carbon tetrachloride, acetone, dimethyl sulfoxide, etc. placed in a sealed liquid pool, or inorganic crystal materials such as diamond and yttrium vanadate.

[0010] A method for broadband rapid wavelength tuning, comprising the following method:

[0011] S1: First, build a ring resonator optical parametric oscillator including a first cavity mirror, a second cavity mirror, a third cavity mirror and a fourth cavity mirror, wherein the first nonlinear crystal is arranged between the first cavity mirror and the second cavity mirror, and the second nonlinear medium is arranged between the third cavity mirror and the fourth cavity mirror;

[0012] S2: simultaneously turning on the first laser source to generate the first coherent light and the second laser source to generate the second coherent light, which enter the resonant cavity from the first cavity mirror and the third cavity mirror respectively, and the first coherent light generates the idle light and the signal light after passing through the first nonlinear crystal;

[0013] S3: By controlling the temperature of the first nonlinear crystal, the wavelength of the idle light and the signal light is coarsely tuned. In each coarse tuning interval, the intensity of the second coherent light injected into the second nonlinear medium is changed. The wavelength of the idle light and the signal light will change rapidly and continuously within a small range to achieve fine tuning.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention adds a second nonlinear medium with Raman activity in the ring resonator, utilizes the phase change caused by the stimulated Raman scattering process to realize the phase control of a coherent light beam in the three-wave interaction, and realizes the fast and broadband wavelength tuning of the signal light and the idle light.

[0016] 2. The present invention proposes a stimulated Raman phase shift controlled optical parametric oscillator comprising two nonlinear media, which realizes rapid control of the wavelengths of signal light and idle light through a pump intensity-dependent stimulated Raman scattering process, thus filling the technical gap in wide-band rapid matching wavelength tuning. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of the broadband fast wavelength tuning device of the present invention;

[0018] Figure 2 is a schematic diagram of the ring resonator of the present invention;

[0019] Figure 3 The graph is a curve showing the change of the wavelength of the signal light and the idle light with the tuning time of the present invention.

[0020] In the figure: 1. first laser source; 2. second laser source; 3. first coherent light; 4. second coherent light; 5. ring resonator; 501. first cavity mirror; 502. first nonlinear crystal; 503. second cavity mirror; 504. third cavity mirror; 505. second nonlinear medium; 506. fourth cavity mirror; 6. idle light; 7. signal light. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0022] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1-3 The present invention provides an embodiment: a wide-band fast wavelength tunable light source device, comprising a first laser source 1 and a second laser source 2, wherein the first laser source 1 generates a first coherent light 3, which is coupled into a ring resonator 5 to achieve optical parameter conversion and output an idle light 6 and a signal light 7. The second laser source 2 generates a second coherent light 4, which is coupled into the ring resonator 5 from another port.

[0026] Furthermore, the first laser source 1 adopts an all-solid-state continuous single-frequency laser with a central wavelength of 1064 nm.

[0027] Furthermore, the second laser source 2 adopts a fully solid-state continuously tunable titanium sapphire laser with a tuning range of 700nm to 930nm.

[0028] Furthermore, the first nonlinear crystal 502 is a periodically poled lithium niobate crystal with a poling period of 29.8 μm, and the second nonlinear medium 505 is a diamond crystal.

[0029] Further, the ring resonator 5 includes a first cavity mirror 501, a first nonlinear crystal 502, a second cavity mirror 503, a third cavity mirror 504, a second nonlinear medium 505, and a fourth cavity mirror 506. Among them, the first cavity mirror 501 is an input cavity mirror, and the coating is HT@1064nm, HR@1.54~1.75μm (HT means high transmittance, HR means high reflectivity), the second cavity mirror 503 is an output cavity mirror, and the coating is HT@2.7~3.4μm, HR@1064nm&1.54~1.75μm, the third cavity mirror 504 is an input cavity mirror, and the coating is HT@932nm, HR@1064nm&1.54~1.75μm, and the fourth cavity mirror 506 is an output cavity mirror, and the coating is T=2%@1.54~1.75μm, HR@1064nm (T is transmittance). In the resonant cavity, the first coherent light 3 may be reflected to the second nonlinear medium 505 through the second cavity mirror 503 and the third cavity mirror 504 , and the second coherent light 4 may be transmitted to the second nonlinear medium 505 through the third cavity mirror 504 .

[0030] At the same time, the first laser source 1 and the second laser source 2 are turned on to generate 1064nm single-frequency laser and 932nm single-frequency laser respectively. When the temperature of the periodically polarized lithium niobate is controlled to be 120℃, the power of the 932nm single-frequency laser is controlled to increase from 0W to 5W, and the tuning ranges of the wavelengths of the signal light 7 and the idle light 6 are 1558.8687-1558.9023nm and 3351.6694-3351.5142nm respectively. On this basis, the temperature control temperature of the periodically polarized lithium niobate is changed rapidly in steps, and the wavelength scanning of the signal light 7 and the idle light 6 in the range of 1558.8687-1584.8878nm and 3237.397-3351.6694nm can be realized within 1 minute.

[0031] The above is only an embodiment of the present invention, and the common sense such as the specific structure and characteristics mentioned in the scheme is not described in detail here. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims. Any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A broadband fast wavelength tunable light source device, comprising a first laser source (1) and a second laser source (2), characterized in that: The first laser source (1) generates a first coherent light (3), which is coupled into a ring resonator (5), realizes optical parameter conversion at a first nonlinear crystal (502) and outputs idle light (6) and signal light (7), and the second laser source (2) generates a second coherent light (4), which is coupled into the ring resonator (5) from another port and is coaxially injected into a second nonlinear medium (505) with the first coherent light (3).

2. A broadband fast wavelength tunable light source device according to claim 1, characterized in that: The second laser source (2) is a continuously tunable laser, and the difference between the operating frequency of the generated second coherent light (4) and the operating frequency of the first coherent light (3) is equal to the intrinsic Raman frequency shift corresponding to the strongest Raman mode of the second nonlinear medium (505).

3. A wide-band fast wavelength tunable light source device according to claim 1, characterized in that: The ring resonator (5) comprises a first cavity mirror (501), a first nonlinear crystal (502), a second cavity mirror (503), a third cavity mirror (504), a second nonlinear medium (505), and a fourth cavity mirror (506); the first cavity mirror (501) is arranged on the right side of the first laser source (1); the first nonlinear crystal (502) is arranged on the right side of the first cavity mirror (501); the second cavity mirror (503) is arranged on the right side of the first nonlinear crystal (502); the first coherent light (3) is coupled into the first nonlinear crystal (502) via the first cavity mirror (501) to realize optical parameter conversion; and the first coherent light (3) is coupled into the first nonlinear crystal (502) via the second cavity mirror (503) to realize optical parameter conversion. ) outputs idle light (6), outputs signal light (7) through a fourth cavity mirror (506), a third cavity mirror (504) is arranged on the right side of the second laser source (2), a second nonlinear medium (505) is arranged on the right side of the third cavity mirror (504), a fourth cavity mirror (506) is arranged on the right side of the second nonlinear medium (505), the second coherent light (4) is coupled through the third cavity mirror (504) and coaxially injected into the second nonlinear medium (505) with the first coherent light (3) circulating in the resonant cavity, and the phase of the first coherent light (3) after passing through the second nonlinear medium (505) changes with the intensity of the injected second coherent light (4).

4. A broadband fast wavelength tunable light source device according to claim 3, characterized in that: The first nonlinear crystal (502) is a nonlinear crystal, such as lithium triborate, periodically poled lithium niobate, or periodically poled potassium titanyl phosphate with angle / temperature phase matching. The second nonlinear medium (505) is a nonlinear medium with strong Raman activity, specifically methane or sulfur hexafluoride gas placed in a sealed gas pool, or organic liquids such as benzene, carbon disulfide, carbon tetrachloride, acetone, dimethyl sulfoxide, etc. placed in a sealed liquid pool, or inorganic crystal materials such as diamond or yttrium vanadate, etc.

5. A method for broadband rapid wavelength tuning, characterized in that: The following methods are included: S1: First, a ring resonator (5) optical parametric oscillator is constructed, which includes a first cavity mirror (501), a second cavity mirror (503), a third cavity mirror (504) and a fourth cavity mirror (506), wherein the first nonlinear crystal (502) is arranged between the first cavity mirror (501) and the second cavity mirror (503), and the second nonlinear medium (505) is arranged between the third cavity mirror (504) and the fourth cavity mirror (506); S2: simultaneously turning on the first laser source (1) to generate the first coherent light (3) and the second laser source (2) to generate the second coherent light (4), which enter the resonant cavity from the first cavity mirror (501) and the third cavity mirror (504) respectively, and the first coherent light (3) generates idle light (6) and signal light (7) after passing through the first nonlinear crystal (502); S3: By controlling the temperature of the first nonlinear crystal (502), the wavelengths of the idle light (6) and the signal light (7) are coarsely tuned. In each coarse tuning interval, the intensity of the second coherent light (4) injected into the second nonlinear medium (505) is changed, and the wavelengths of the idle light (6) and the signal light (7) are changed rapidly and continuously within a small range, thereby achieving fine tuning.

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