TW200410464A - Optical parametric oscillator with distributed feedback grating or distributed bragg reflector - Google Patents

Abstract

The invention relates to a simple and effective laser device for generating laser radiation from an optical parametric oscillator (OPO) by implementing a distributed feedback (DFB) or distributed Bragg reflector (DBR) structure, in the laser oscillator. The nonlinear crystal used in the OPO of the present invention can be a birefringence phase-matched crystal or a quasi-phase-matched crystal.

Description

200410464 V. Description of the invention (1) [Field of the invention] The present invention relates to — + ^ relates to a method using a field shot, and in particular, the present invention constructs a structure through which a Γ ... (Bragg dif fraction) Grating junction &#, nine academic parameters oscillating radiation device. One or near a Bragg winding = internal optical material or laser gain material internal device 0P0) generates a laser radiation laser [invention of the present invention, a space full of optical light reflected on the Bragg fiber — when the laser is on, the laser is emitted. — Point, due to the oscillating matter, the two grating systems, the radiation gain phenomenon can be referred to as the background system], and the wavelength of the Bragg grating is discussed. Become a radiation gain laser through the dispersion type. The cloth at the end of the branch can be made of material. This is one of the dispersion theory. 4l, ¾ ^ 格 条 # Lattice diffraction grating is a kind of optical wavelength that can be used under moderate conditions. (2〆〆m) and the refractive index of the light wave, Λ # This grating factor /, a positive ^ number. Also, this wavelength is also called Λ ". A Bragg diffraction grating system can be manufactured in an object, a fiber grating. When a Bragg diffraction grating system is manufactured, the two ends of the shell are used to replace a group of laser resonator mirrors. The system is called a decentralized Bragg reflector (Dual Bragg Reflector (DBR) laser system, which has a convenient & diffuse Bragg reflector (DBR) laser. A laser gain gastric grating diffraction grating is replaced. In addition, a Bragg ^ 2 is used on the entire laser gain material, and is not limited to the two ends of the laser. The scattered optical feedback caused by this grating element is near the Bragg wavelength. This kind of ^^^ type feedback (DFB) laser. Due to a decentralized feedback " 200410464 V. Description of the invention (2) (DFB) internal non-causation of laser. It has different laser enhancement , W produced 1 (Dngl tudinal mode), this decentralized return to DF ^ gas 4 strict longitudinal mode of laser input (Pu laser also has scattered Bragg reflectors, some distributed Bragg reflectors (DBR) However, DFB) structure has been widely used in semiconducting Belle, in a variety of applications of a semiconductor laser. Gap (energy band, day / thousands of conductors, moons, moons, pulls, and reflections) DRW and can not follow these scattered Bragg reflections σσ (DBR ) And decentralized feedback (DFB)

Make arbitrary choices to make wide-area changes. ° 'One way to modulate a laser wavelength is to use a non-linear optical material. As early as 1962 AD, A. Armstrong et al. Proposed a non-linear frequency conversion technique of quasi-phase matching (QPM) in Phys Rev. 1 2 7 (19 2 2) 1 9 1 8. For example, solid-state laser-excitation optical parameter generation (OPG) and optical parameters from periodically polarized lithium niobate (PPLN) solid-state lasers

Oscillation (ΟΡΟ) has provided an effective laser light source capable of wide-area modulation (such as Myers et a 1. Journal of Optical Society of America B, vo 1. 1 2 (1 9 9 5) pp · 2102— 2 1 1 6). However, the optical parameter generation system generates a broadband radiation. At mid-infrared wavelengths, the solid-state laser-excitation optical parameter generation (0PG) of periodically polarized lithium niobate crystals (PPLN) may have a spectral width exceeding several nanometers (nm). Therefore, in order to obtain effective narrow-line laser radiation,

Page 9 200410464 V. Description of the invention (3) The optical parameter oscillator (oop) of QPM is a universal device. A conventional linear resonator optical parameter oscillator (OP0) can benefit the high f i n e s s e value of its resonator to produce a narrower line width output, but Thai half still has multiple longitudinal mode outputs. In order to obtain a single longitudinal mode output, an operator usually #, must use a more complex resonator design (such as B o s e n b e r g e t al. ’Applied Physics Letters, vol. 61 (1992) PP · 3 78— 3 8 9). Therefore, if an operator can oscillate a (DFB) prior learning parameter into a non-linear optical substance, 1 ^ K to obtain ^ in the adjustment range of this oscillator, the author can know the Bragg wavelength «-2 Laser wheel with single frequency oscillation. Structure can, situation. [Introduction of Invention] The above-mentioned problems encountered by Wenjin [Summarization of Invention] In order to solve the above and other problems, a simple and effective laser device department manufactures a Bragg diffraction grating to generate laser shots. However, the body of this nonlinear optical material or a quasi-phase matching crystal. Another object of the present invention is to provide 'its system in this nonlinear optics, Gan / A q M you order, the second system in this non-linear optics 5, mistakenly through an optical watch system can be Sheng 1 ( 〇p (Γ Draws effective laser-type decentralized feedback with 疋 -birefringence phase matching

For a simple and material implementation

200410464 V. Description of the invention (4) (DFB) or decentralized Bragg reflector (DBR), so as to generate a laser with a narrow bandwidth through an optical parameter oscillator. However, the non-linear optical material used in the optical parameter oscillator (OP0) of the present invention may be a birefringent phase-matched crystal or a quasi-phase-matched crystal. Among them, the distributed feedback (DFB) structure performs periodic refractive index modulation on the entire non-linear optical substance, so that the light beam with a wavelength matching this modulation period will cause optical oscillation; the distributed Bragg reflector (DBR) system will The modulation of the periodic refractive index is implemented at both ends of the non-linear optical substance, so that a light beam with a wavelength matching this modulation period will cause optical oscillation. The main feature of the present invention is to provide a laser device, which uses a non-linear optical element to generate a laser with a narrow bandwidth through an optical parameter oscillator (OP0), wherein the non-linear optical element has a light A decentralized feedback (DFB) grating with a refraction effect, oscillates at least one wavelength of the mixing wavelength of an optical parameter by using a specific period $ distributed feedback grating to obtain a high-efficiency laser output. Another feature of the present invention is to provide a laser device, which uses a non-linear optical element to generate a laser with a narrow bandwidth through an optical parameter resonator (OP0). The non-linear optical element has A decentralized Bragg reflector (DBR) structure with a photorefraction effect, by which a Bragg reflector with a specific period oscillates at least one wavelength of a mixing wavelength of an optical parameter, to obtain a high-efficiency laser output. Preferably, the distributed feedback (DFB) structure or the distributed Bragg reflector (DBR) structure reflects electromagnetic waves near the first order (m = 1) or above (2) Bragg wavelength (also = 2 ηΛ g) Of which Λ 谗 一 布

Page 11 200410464 V. Description of the invention (5) The period of the grating diffraction grating, and the system can be any non-linear mixing wave element. The system has a second-order non-linear optical refractive index, which has the Bragg wavelength in this medium. The equivalent lattice reflector (DBR) knotted feedback (DFB) structure or this decentralized bran oscillates. This Bragg laser device can be long at the Bragg wavelength λ. Preferably, the non-linear light wind coefficient (Sec0nd ~ 0: rde: r to π coefficient) is ^ 〇Ptical is better, this optical table number ^ linear crystal, star, oscillator ( 0P0) is based on bulk non-effect decentralized feedback (DF = phοt〇refraction) The better one is 'this optics counts', the waveguide nonlinear crystal number device ( 〇Ρ〇) is based on a waveguide decentralized feedback (DFB). It has a built-in light refraction effect. The optical parameter vibrator (0P0) is attached to a bulk (non-bulk), and 1 has' Decentralized Bragg reflector (DBR) structure with built-in light refraction effect. Preferably, the optical parameter oscillator (OP0) is inside a waveguide (waveguWe) nonlinear crystal and has a decentralized form with built-in light refraction effect. Bragg reflector (DBR) structure. Better, this nonlinear optical crystal system is a birefringent phase-matched crystal. Fortunately, this nonlinear optical crystal system is a quasi-phase-matched crystal. Better, this nonlinear optics Crystal system

Page 12 200410464 or lithium silverate, or impurity doping V. Description of the invention (6) Linear optical crystals, such as the same optical crystals of lithium niobate. @ # Another feature of the present invention is to provide a laser device. The second system utilizes a non-linear optical element to generate a laser with a narrow bandwidth by using a parameter:! P〇), where this non-linearity Optics ^ Decentralized feedback (DFB) or decentralized cloth with a refractive effect: Reflective (DBR) structure, and wherein the method of modulating the optical refractive index irradiates a light beam to penetrate it Light refraction effect

Photomask 〇 Preferably, this photomask has a grating design. After a light beam is radiated, a spatial light intensity change matching the optical parameter Bragg condition (ορό) Bragg condition is generated behind the photomask. Preferably, the light beam is an optical writing beam, which has the effect of inducing a space charge (s p a c e charge) inside the non-linear optical material of the light refraction effect. Preferably, the light beam is located at a wavelength of visible light or ultraviolet (UV) light. Preferably, the non-linear optical element is made of a second-order nonlinear optical coefficient. Another characteristic branch of the present invention

Non-linear optical element, a laser device provided by rk, which uses a lifetime narrow band laser, so an optical parameter oscillator (0P0) produces a non-linear optical element system shaped by the light refraction effect. Bragg reflector (J ^ B, DFB structure or dispersion) structure, and wherein the optical refractive index is adjusted

200410464 V. Description of the invention (7) '~~~ --- ^ The I method uses an interferometric photorefractive effect to write J, and the two laser beams intersect and the laser beam passes through the optical interference effect to make :: 声 ▲ 月 二The spatial optical intensity modulation is generated in Yuwu, and the spatial optical intensity & decay causes the optical refractive index modulation. Strong, good, the periodicity of this interference fringe is matched to the Brahmin condition expected by this light (0P0) operation. Another feature of the digital vibration amplifier is to provide a laser device that uses a 7G optical element to pass through an optical parameter oscillator (〇p〇) The linear optical element has a production-based dispersion formed by the electro-optic effect; ^ (DFB),, a non-linear optical element of bismuth, by which the space is periodically tuned along two ~ The refractive index in the direction. The periodicity of this refractive index change matches the Bragg conditions expected from the operation of this optical parameter oscillator (OP0). ， 非 ί S Ξ ί Another feature is to provide a laser device, which uses ~ 隹, a sexual optical element, so as to pass through an optical parameter oscillator (laser laser with a narrow bandwidth, where this non-linear optical element It is a distributed Bragg reflector (DBR) grating that produces light, and its, medium, and one-to-one electrical = non-linear optical elements added to this electro-optical, thereby periodically- Refractive index in the direction of transmission. The periodic Biman of this refractive index modulation is suitable for the operation of this optical parameter oscillator (OP0), which is the best. ≪ Better Bragg strip, the amount of refractive index change, Its simplified form is / expressed as: △ η = (1/2) rn3E, where r is the crystal envy ^ is the electro-optical system of 馐

Page 14 200410464 V. Description of the invention (8) Number, η is the refractive index without voltage applied, and e is an electric field inside the crystal. 0 Another feature of f is to provide a laser device, which is passed through a The optical oscillator (0P0) generates a narrow-frequency laser. This optical parameter oscillation is based on a non-linear optical waveguide surface with a corrugated distributed feedback (DFB) structure. The decentralized feedback of the evanescent wave is sufficient to activate the optical parameter vibrating disk. More specifically, this distributed feedback (DFB) structure is fabricated using methods such as material etching, thin film coating, lithography, ion implantation, and combinations thereof. The feature is to provide a laser device, which generates a narrow-frequency laser via _ (0P0). The optical parameter of the optical waveguide (waveguide) has a wave-shaped diffuse Bragg reflector (DBR) structure. The decentralized form of the evanescent wave reverts to a number of oscillations. Stomach 11 Scattered Bragg Reflector (DBR) structure is a film coating, lithography process, and a combination of these features. ^ The feature is to provide a laser device that generates a narrow-frequency laser via-(〇Ρ〇) ， This optical parameter is a two-way reflector with a decentralized feedback 13 Bragg reflector (DBI0 structure, by which, JB)

Another optical parameter oscillator of the present invention is based on a non-linear (corrugated) component which is sufficient to start the optical parameters on the surface of the waveguide, such as material etching and thin line fabrication. Another optical parameter oscillator of the present invention is a non-linear structure or a decentralized type.

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200410464 V. Description of the invention (9) The optical feedback of the Bragg scattered electromagnetic wave inside the waveguide can be enough to start the optical parameter oscillation. The better one is that the distributed feedback (DFB) structure or the distributed reflector (DBR) structure belongs to the photorefractive type described above. Compared with this, the distributed feedback (DFB) structure or the distributed Bragg r 0 ~ reflector (DBR) structure belongs to the above-mentioned type of electro-optic effects (elect optics effect). In the following invention, the coefficient oscillates, and the internal frequency is composed of two light angular frequencies ω s ω s + ό 而言 γ [Generally speaking, although more. (Using the limitations of this study, the vibrator system has a detailed description of the frequency ω]] The Ming system can allow many different forms of preferred embodiments, and only some of the preferred embodiments will be described in detail and disclosed by the present invention. It is used to prove the principle of the present invention, not the scope of the present invention, or the specific embodiments described in the broader description of the present invention. Crying—The optical feedback of the Lag diffraction grating is used to help establish the optical parameter oscillation of a light f. Fig. 1 introduces the conventional techniques. A non-laser (PumP laser) 10 series excites a laser and learns 2 = 2 optical elements 30. Among them, the laser resonance ω A helps 畚 = 2 0. In the course of an optical parameter, < two light and one photon. The high-frequency photon system is called a signal light (Slgnal) according to the following relationship, and this

Page 16 200410464 V. Description of the invention (ίο) The low-frequency photon system is called idle ~ ^ one one 'one ~' — can oscillate this signal light, medium (i d) er). At this point both are oscillated. It is also possible to oscillate the intervening light (two /, the vibrator mirror surface 20 according to the present invention ... Xier 1 er), or the content of the same-speech optical element is true of these resonant cryo-rag reflectors " feedback (built decentralized feedback (DPr / Structural replacement, such as the 2nd place-or a non-Γ structure or a decentralized structure of a put-on cloth () structure. Any device with one inside, not "4" Figure 2b of the optical element emitter, the present invention "4 Springs 45, 46: Figures 2b through 6t. In a linear optical monolithic material, the 丄 oscillator (0pc0 eroded field map. This nonlinear light wind w 'decentralized feedback (df) Refractive index modulation, =: f The summary modulation period of the entire long structure of the material or this-heavy number 1 and 2 have a periodic condition. White Bragg grating period, Λ & No. This refractive index h , ^ / 2ns, or / to satisfy Prague! 1 g, f iU 〆 2ni and η, where ^, λ, and λ are the wavelengths of the signal light and interposed photons, respectively, see 绫 ί The lc diagram is the equivalent refractive index seen in the optical parameters of the present invention: in the optical monolithic material, the device (_ 所 H #! rag diffraction grating 50 The two ends of the two materials are oscillated by Γ ΠΡΓί, so you can use these mirrors. In addition, the optical parameter of the present invention & two Bragg diffraction gratings

^ Page 2004 200410464 V. Description of the invention (11) Non-linear optical material 5 The 5-segment system remains unchanged for optical frequency conversion. Figure 3a is a schematic diagram of a distributed feedback (D F B) structure in an optical waveguide used in the optical parameter oscillator (OP0) of the present invention. The non-linear optical waveguide 60 has a wave-like periodic structure above the entire device length, that is, a decentralized feedback (DFB) structure 80. The distributed feedback (DFB) structure 8 0 reflects the surface dissipated waves of the waveguide to establish the non-linear

The optical parameters inside the linear optical waveguide 60 oscillate. The non-linear optical waveguide 60 is fabricated on the surface of a suitable material substrate 70. For example, a non-linear optical waveguide system can be fabricated using the so-called annealed proton exchange method (M. L. Bortz et a 1. Optics Letters vol. 16 No. 23 (1991) PP. 1 844-1 846). On the surface of a lithium niobate base. Another embodiment of the Bragg diffraction grating. 3b. The nonlinear optical waveguide 60 is embedded with periodic refractive index changes, that is, embedded distributed feedback (DFB) structure 84, and embedded embedded feedback (DFB). Structure 84 'may be, for example, a photorefractive effect, an ionic phase

Cion imp lan tat i〇n) or thermal penetration (thermal ma te: r, etc.). When using light refraction to cause a beam :: via-optical mask or using laser interference ",

^ The spatial variation of the intensity of the two beams is periodic; and the use of cloth ^? 丄 = a lithographic mask required for the lithographic process. The empty 2 cycles' then use this mask to match the area with variable refractive index; the surface is covered with a mask, which does not need to be changed, but only the area where the refractive index needs to be changed is exposed and

Page 18 200410464 V. Description of the invention (12) Progressive electrode Perform ion implantation or thermal penetration. If so, the embedded DFB) structure 84 can directly provide the fractional feedback optical waves inside the optical waveguide 60. This blaard gives feedback to this non-linear example. Figure 3c is on this non-linear optical waveguide = = another real 8 7 of the first grid. A voltage is applied to this periodic electrode 8 and a periodic electricity should be generated by the gas. The periodic refractive index changes, and H # 2 can pass between the electro-optical effect optical waveguide 60, if necessary, an electrode 87 and a non-linear layer) 90, such as silicon dioxide (Si0 ,, The layer, buffer layer (Buffer loss caused by direct contact. If it is: 2 wave and electrode 87 (DFB) structure can directly provide the 4 electric # optical angle effect decentralized feedback optical wave inside the optical waveguide 60. Worker Feedback to this non-linear Figure 4a is a prior image of a decentralized Bragg reflector f in the optical waveguide of the optical parameter oscillator (〇p〇) of the present invention. A Bragg diffraction grating is placed on the length a of the decentralized feed king. In this preferred implementation, a non-linear optical waveguide 60 is provided on the surface or inside of the Bragg diffraction gratings at both ends of the device, that is, a decentralized Bragg reflector (DBR) structure 50. Optical Waveguide (DBR) 50 Nonlinear Optical Waveguide 55 Retains unchanged. Another embodiment of the decentralized Bragg reflector (DBR) is a periodic refractive index change after the content of the non-linear optical waveguide 60, that is, an embedded decentralized Bragg reflector ( DBR) 54. The periodic refractive index change is embedded, for example, it can be caused by light refraction, ionic implantation or thermal materiai diffusi〇n.

200410464 V. Description of the invention (13) and other methods Optical space The space required by the space program is appropriately made and needs to be changed. For example, if the light of the straight part 4c is shown in Figure 57, a layer of Zhou Xue waveguide is generated: directly reflect to this non-ΐ ί go Ϊ: write under the light refraction effect ~ the light beam can pass through the -shield or use the interference fringe, I Periodic changes in the intensity of the writing beam, and using a lithographic mask, ^ ”” can be made first lithography system ~ You Zao This mask has a condition that meets the Bragg diffraction conditions y, = used, the mask cooperates with the micro The film is made on the surface of the waveguide with a 4 shell cover, which covers the area without changing the refractive index.

Ϊ́ 2i or bare and ion implantation or thermal infiltration, the 7-blade diffuser Bragg reflector (DBR) structure 54 is then provided to provide distributed optical readback to this nonlinear optical waveguide # 6〇 More waves. In another embodiment of the Bragg Diffraction Reflector (DBR), a periodic electrode is made at both ends of the non-linear optical waveguide 60 and a voltage is applied to the periodic electrode 57. Between the periodic electrode 57 and the non-linear light 60 ', if necessary, a buffer layer (Buf f) 100, such as silicon dioxide (Si〇2), may be added to avoid light waves and the electrode "producing Loss. If so, this electro-optical effect decentralized Bragg Bracket (DBR) structure can directly provide light waves inside the decentralized Bragg reflection linear optical waveguide 60.

Figure 5 is a schematic diagram of a dynamic chir ped Bragg diffraction grating, which is used as a distributed feedback (DFB) structure or a distributed Bragg reflector for a nonlinear optical material used in the present invention ( DBR) structure is another preferred embodiment. Generally, a Bragg diffraction grating system can have an arbitrary refractive index change in space, which is reflected by this Bragg condition and the spatial Fourier component (Fourier component in the Bragg diffraction grating).

Page 20 200410464 V. Description of the invention (14)-2): Optical wavelength. 13 Thus, the reflection of-Bragg diffraction ^ ^ 仏 can correspond to the Fourier of this Bragg diffraction grating with a 0 ^ r; ler) complement conversion spectrum. A dynamic frequency-shifted Bragg diffractive grating system is used in Guan Xing if (Fourier) to convert the frequency spectrum, and is therefore suitable for f-frequency prior learning unit oscillator (0P0) operation. FIG. 6 / is a schematic diagram of a cascaded Bragg diffraction grating 'which is used as a distributed back-^^ DFB) structure or a distributed Bragg reflector (DBR) structure of a nonlinear optical material used in the present invention Another preferred embodiment. This cascaded Bragg diffraction grating Q, Yu 'oscillates in the optical parameter oscillator (0P0) in each Bragg grating (90, Go · 9 9) with different grating periods, and Γ Ϊ simultaneously Through this optical parameter oscillator (OP0), several types of lightning are generated. 要 To this Cascaded Bragg diffraction grating, Πηϊ, 2 optical parameter oscillator (within the bandwidth, the hair is long. Thousands of oscillation benefits (〇po) can produce multiple laser wave parameters at the same time; ί! T non-sex optical components are used-in optical can use light refraction to rub \ material into the material, in this single block Or in the refractive effect material of the waveguide element, the ratio of g = in-Bragg diffraction grating. The spatial modulation of the intensity of the light beam with the spatial modulation of the spatial modulation, the shape, the nonlinear optical material Ϊ f charge Distribution. The intensity of the electro-optic effect coupling is used to adjust the space. The emissivity is based on the space of the writing beam. The writing beam system can be used. For example,-the spatial intensity modulation. This optical refraction effect is a nonlinear optical element. on

Page 21 200410464 V. Description of the invention (15) Fang Zhi's mask is implemented, in which the mask produces a specific period of light intensity change in space after being illuminated by a light beam, and the light intensity change period matches the expected Bragg refraction grating cycle. For example, a phase mask is used to interferingly write a light beam into this nonlinear optical material, and the interference fringe period is matched to the expected Bragg refraction grating period. Furthermore, two laser beams with an appropriate angle can also cross directly, so as to form a periodic interference intensity in the non-linear optical crystal with photorefraction effect, and then write into the Bragg diffraction grating with photorefraction effect. When an electro-optic nonlinear crystal system is used as the gain material of an optical parameter oscillator (0P0), an electro-optic Bragg diffraction grating may be implemented in this monolithic or waveguide crystal. First, the microelectrode system can be fabricated on a non-linear crystal with an electrode distribution by using sign technology. The electrode distribution system matches the Bragg structure distribution. When a voltage is applied to these microelectrodes, the electric field strength inside the crystal induces a change in refractive index through the electro-optic effect, thereby forming an electro-optic Bragg diffraction grating inside the crystal. For example, if a 0.5mm thickness, zeta cut (ζ-cut) periodically polarized lithium niobate crystal (PPLN) is an optical parameter oscillator (0P0) used for quasi-phase matching, then the soil zeta of the crystal A periodic microelectrode can be fabricated on the surface and a voltage can be applied to form a Bragg diffraction grating according to the following equation. Δ η = (1/2) r33n3Ez Wherein, when these microelectrodes are applied with a voltage of about 100 volts, the refractive index change is at Δ n = 1 0-depleted level. If a non-linear optical waveguide is used for an optical parametric oscillator

Page 22 200410464 V. Description of the invention (0P0), technique, making lithographic etching grating. The device (DBR) becomes an optical parameter and the film is overlaid. (16) " " ^ --— Then the Bragg diffraction grating system can use the lithography technique to obtain the surface of the waveguide. A process often used in semiconductor processing is to form a wave-shaped Bragg on this non-linear waveguide, such as a distributed decentralized feedback (DFB) or decentralized Bragg inverse polar laser. The Bragg reflection of this dissipated wave is sufficient. Count, swing. Alternatively, this Bragg diffraction grating system can use 1 and micro, and time-cut technology to form a non-linear waveguide. For example, a layer of material thin film is first covered on this non-linear = and this' special film is chemically or Electropolymerization is engraved to a Bragg diffraction grating. ,1

[Experimental Results] Due to the photorefractive effect material of the lithium niobate crystal system, it is possible to write a distributed feedback (DFB) structure or a dispersed form formed by the photorefractive effect in a periodic acid sharp crystal (PPLN). Prague reflection ^

(DBR) structure. In particular, in a periodically polarized lithium niobate crystal (PPLN), 'if the optical parameter oscillator (0P0) mirror surface can be replaced with a distributed feedback (ρρΒ) structure or a fractional Bragg reflector (DBR) structure', then optical The design of the parametric oscillator (〇PO) will be greatly simplified. In this experiment, a periodically polarized lithium niobate crystal (PPLN) has two periodically polarized lithium niobate crystals (ppLN) dispersed feed (DFB) optics with a photorefractive effect dispersed feedback (DFB) grating. Parametric oscillator. Among them, a diffuse feedback (DFB) grating, which is caused by light refraction ^, uses ultraviolet radiation to penetrate through ^

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V. Description of the invention (π) Periodically polarized lithium niobate crystal (PPLN) u 'and the other 2 formed by the photorefractive effect, the photomask is made by' is using two 5 32 dragon wavelength laser light Formula (DFB) light booths are polarized in lithium niobate crystals (PPLN). "Stripes' are written in this cycle in the ultraviolet (UV) limit shown in Fig. 7. In the non-homogeneous ultraviolet (UV) surface of the silver lamp, the method is" from the 20 W water period, 50% work. " Chrome mask for cycles. Fields and rays of light have 1 " m circumferential filters (UV), which can only pass through the ultraviolet light of water _ 7 silver gallium. After this ultra-violet (UV) filtering, the optical intensity of the 3 to 5 dragons is about 0.3 W / cm2. This optical 1 cover mI cover is 3 6 5nm ρ Λ r wide. . The hood is in direct contact with a 4cm long, 0.5mm thick, 2M tuned, and end polished (end-ishe periodic polarized sharp acid crystal (PPLN). Its chromium grating vector (grating vector) is aligned with the crystal. The quasi-phase matching (QPM) grating in the χ direction is 1. When the ultraviolet (υν) radiation is transmitted through the mask, the temperature of the periodically polarized lithium sharp acid crystal (PPLN) rises from 20 C to 3 minutes 160 C, and reduced from 16 to 20 ° C over a two-hour period. In this way, the 'UV (UV) -induced light refraction effect dispersion feedback (DFB) grating can be recorded in periodically polarized lithium niobate Crystal (PPLN). This 1 / zm distributed feedback (DFB) grating period system can periodically polarize lithium niobate crystals at a temperature of 1 15 · 4 ° C and a pump (pUmped) of 1 0 64 nm. PPLN) generates an oscillation for 4. 0 8 5 β m idle photons. Its corresponding signal wavelength is 1 4 3 8 · 8 nm. Passive q using 9 VJ / pu 1 se pulse energy and 7 3 0 ps pulse width Q (switched) Er-doped garnet (Nd: YAG) laser pump decentralized return

Page 24 200410464 V. Description of the invention (18) Feed (DFB) periodically polarized lithium niobate crystal (ppLN). This distributed feedback (DFB) optical parameter oscillator (opo) signal system can be used at i 43 8. 8 nm produced. This signal spectrum is measured after a monochromator with a length of 1/2 m and is measured with an inGaAs ingot. The resolution of this monometer is 3 A, which has a 1 "claw slit opening and an infrared grating of 3 0 0 1 i ne s / mm. The pulse width of this 7 3 0 p3 pump is approximately equivalent to this 4 The length of a single cycle of the periodically polarized lithium a sharp acid crystal (PPLN) with a length of cm is one round trip time, so the periodic polarization of a sharp acid without a specific film is not formed on the two surfaces of the crystal (PPLN). > Figure 8 shows the optical parameter oscillator (oop) and optical parameter generation (0PG) signal spectra at different temperatures. As can be seen from Figure 8, although the optical parameter generation (0PG) wavelength is shifted with temperature, the optical The parametric oscillator (0P0) signal wavelength remains unchanged due to the light-refracting effect distributed feedback (DFB) grating inside the periodically polarized lithium niobate crystal (PPLN). At a temperature of 1 1 5 · 4 ° C, this The optical parameter generation (〇pg) wave ^ is partially overlapped with the optical parameter oscillator (OP0) signal wavelength, and the conversion between the two parameters is greatly improved by 3 times. The distributed feedback (DFB) optical parameter oscillator (OP0) signal The measured spectral width is 3A, and the amount of optical parameter generation (0PG) signal The spectral width is 3 nm. When the pump energy is 6 · 7 5 // J, the output signal energy is 1 v J, which is equivalent to 15% of the signal light energy conversion rate. U Because of the distributed feedback (DFB) grating vector system Crystal X direction, this distributed feedback (DFB) grating may be expected to be a space charge in the X direction

200410464 V. Description of invention (19) Caused by field E. However, the z-polarized (ζ — ρ ο 1 arized) pump space electric field induced (E χ — induced) refractive index change is the second-order effect of sharp acid inside, which is expressed as: 3 (rwEO 2/2 Equation (1) where η and η, 2.2 are normal and abnormal refractive indices, respectively, and r 51 ~ 3 2 pm / V is the electro-optic coefficient of lithium niobate. In a stable equilibrium state It is dominated by thermal diffusion and approximated by non-empty carriers. The level of this space charge electric field is approximately Ex «2KkBT / (Aq)« ΐ〇5 v / m, where kB is Boltzmann's constant ), 9 is the charge of an electron, 4 0 K is the crystal temperature, and Λ ~ 1 / zm is the distributed feedback (DFB) grating period. Although this space charge electric field is the refractive index ellipsoid of the rotating sharp acid ( index ellipsoid) and a slight depolarization of the incident optical electric field (deρο 1 ar ize), the change in refractive index seen by this laser is, according to equation (1), only △ η «1 (Γ9. However, Because of the ultraviolet (UV) diffraction that penetrates this optical mask, the The degree changes spatially along the z direction of the crystal. This means that the space charge distribution will also change along the z direction. As the light refraction effect charges change along the z direction, the space charge electric field Ez of the z component will also change. A first-order refractive index change is induced in a periodically polarized lithium niobate crystal (PPLN), which is expressed as: △ nz = n33r33Ez / 2 »105 Equation (2) where r 33» is used in the calculation The number of refractive index changes of 31 pm / V and Ε Ε 10 5 V / ΠΓ is much larger than that calculated by equation (1). In the present invention, the optical parameters of the periodically polarized lithium niobate crystal (PPLN) oscillate

Page 26 200410464

V. Description of the invention The decentralized optical feedback of the (20) device (0P0) is similar to the decentralized feedback (DFB) diode 4 with a wave grating above the gain material. What is more, the wavy light refraction effect decentralized feedback (DFB) grating system can provide sufficient optical feedback and can generate a signal light with a bandwidth that reaches the analysis limit of a single light meter. In order to take advantage of the 乂 -direction space and electric field in periodically polarized lithium niobate crystals (ppLN), the investigability of the optical parameters of the distributed feedback (DFB) to two oscillations (0P0) was further investigated. The read (Dfb) grating is written using a laser beam with an interference wavelength of 5 3 2 nm, as shown in FIG. 9. The circular laser beam is shaped as an elliptical beam with an optical axis ratio of about 1.50 using a lenticular lens group. Subsequently, the 5 32 nm laser with a mean power of 200 m was separated by a beam splitter (beam m s p 1 i 11 e r), and 34. The angles are recombined by: ·· 913 generated on a periodically polarized lithium niobate crystal (PPLN) with a thickness of T =: 0.5 mm, a period of 1 1 // m, an end surface not coated, but optically polished at the end. # m periodic interference fringes. The maximum intensity of this interference laser beam is approximately 0.5 W / cm2. This 0.9 1 3 // m-cycle decentralized feedback (DFB) grating system has no juice to oscillate in a periodically polarized lithium niobate crystal (PPLN) excited at 5 2 2 nm at a temperature of 8 2 C 3 · 778 // m optical parameter oscillator (0P0) idle photon wavelength. This pump laser is a passive q-switched, erbium-doped garnet (Nd: YAG) laser with a double frequency. It is a periodic electrode with a repeatability of 6.59 k Η z and a pulse width of 4 3 0 ps. In a lithium niobate crystal (PPLN), a pulse energy of 2 / z J is generated. These interfering 532 nm laser beams are in a single periodically polarized lithium niobate crystal (ρρ [Ν)

200410464 V. Description of Invention (21), a periodic space charge electric field in the X direction is generated. Although this experiment can clearly see the (0PG) signal generated by temperature-related optical parameters near 620 nm, this experiment could not find any evidence to supplement the equation (1) caused by the small optical refractive index change. Decentralized feedback (DFB) optical parameter oscillator (0P0). While continuously irradiating 5 3 2 nm interference light on this periodically polarized lithium niobate crystal (PPLN), this experiment also irradiated ultraviolet (UV) with an intensity of 53mW / cm2 to the periodically polarized lithium niobate crystal (PPLN) ) + Z surface, and the optical parameter oscillator (0P0) signal of decentralized feedback (DFB) was observed again at the output. Ultraviolet (UV) wavelengths of 3 6 5 nm in lithium niobate are attenuated along the z-direction and are written via the so-called two-photon photorefractive effect writing method (L. Hesselink, eta 1. 9 Science 282 (1998) pp 1089), and a wave-shaped decentralized ore return (DFB) structure is obtained by induction. Figure 10 shows the optical spectrum of the optical parameter oscillator (0P0) and optical parameters of the periodically polarized lithium niobate crystal (PPLN) at different temperatures. It can be seen from Fig. 10 that although the optical parameter generation (0PG) is adjusted by temperature, the signal wavelength of the scattered feedback (DFB) optical parameter oscillator (0P0) of 619.3 nm will still have to be matched due to Here, the Diffraction Feedback (DFB) grating of the light refraction effect remains unchanged. At a temperature of 82.4 ° C, the optical parameter generation (0PG) wavelength partially overlaps with the optical parameter oscillation (OP0) signal wavelength, and the signal intensity is the strongest. When this experimental system moves the pump beam along the ζ direction and in the longitudinal direction, and gradually makes the beam enter from deeper places of the crystal, the distributed feedback (DFB) optical parameter oscillator (OP0) signal system gradually decreases. this

Page 28 200410464

Page 29 ZUU41U404 Schematic description ^ Figure 1 is implemented by an optical laboratory. The vibrating cover is a schematic cross-sectional view of (0P0). As shown in Fig. 2a, the optical watch of the present invention is shown in Fig. 2b, which is a brief introduction of the light wind of the present invention: Zhenying is (0PO). A non-linear used in the I = digital oscillator (OP0) in the monolithic optical monolithic material. Figure 2c is a schematic diagram of the light wind 1 scattered feedback (DFB) structure of the present invention. In the optical monolithic material, there are two non-linear schematic diagrams of one of the oscillators (0P0). Figures 3a, 3b, and 3c of the structure of the diffuse Bragg reflector (DBR)

One of the non-linear optical waveguides is used in the optical parametric oscillator (OPPO). Outline of a Decentralized Feedback (DFB) Structure Figures 4a, 4b, and 4c are schematic diagrams used in one of the non-linear optical waveguides of the present invention. 3 of the Knife Government Bragg Reflector (DBR) Picture Series-Dynamic Frequency Shifted Brato It is used as the outline of a two-to-two shot first grid made by the present invention. Preferred Bragg Reflector (_) Xiao Gou Zhi-Picture 6-CaScaded Bragg Diffraction Light

Used as the non-linear optical field / car used in the present invention =): Γ. Or one of the decentralized Bragg reflectors

Page 30 200410464 Brief description of the diagram The outline diagram of the feedback (DFB) optical parameter oscillator (op0). Figure 8 is the measured signal spectrum of the optical parameter oscillator (OP0) of the deflection feedback (DFB) optical refraction effect in Figure 7. Fig. 9 is a schematic diagram of a two-photon photorefractive effect decentralized feedback (DFB) optical parameter oscillator (OP0) written into a Bragg diffraction grating in a non-linear optical crystal with photorefraction effect using crossed laser beams. Fig. 10 is the summer measurement b 5 tiger spectrum of the two-photon photorefractive effect decentralized feedback (DFB) optical parameter vibrator (OP0) in Fig. 9.

Element symbol description: 10 pump lasers ω s, ω i, ω p angular frequency 3 〇 non-linear optical element 2 0 optical reflecting mirror surface 40, 43, 44, 45, 46 device 2, 3 number 50, 54 Embedded distributed Bragg reflector (Dbr) 5 5 Non-linear optical material 5 7 Periodic electrode 6 0 Non-linear optical waveguide 7 〇 Suitable material substrate 8 〇 Distributed feedback (DFB) structure 84 Built-in distributed feedback (DFB) Structure 87 electrodes 90, 95, 99 Bragg grating 100 Buffer layer

Page 31

Claims (1)

200410464 6. Scope of patent application ___ 1 · A laser device, which is an optical parameter oscillator (7-a non-linear optical element, by which the optical element system has "Π) generates laser radiation, among which? One of the non-β &quot; f-number frequency conversions-Bragg diffraction grating, which is used to vibrate 1 2 · If the first wavelength of the patent application scope, a laser output is formed. Lattice diffraction grating is a decentralized, described laser device, in which: Lattice conditions-grating 4 feed? FB), structure 'Its system has a laser vibration within the matching (〇p〇), which is worse than the optical parameter oscillator. The radiation device 'where' the bla has a matching Bragg chirp 1, Bragg reflector (DBR) structure 'is an oscillator (opn, <a grating period, by which the optical parameter 4 · as described in the laser fort The lattice diffraction grating system is the laser device described in item j1 and f1, wherein the bla matches a blarin's chirped grating structure, which has a parameter oscillation ^, one of the wideband Spatial frequency components, whereby wideband laser amplification or vibrating disk is allowed in the optical 5. As claimed: OP0). Lattice diffraction = The laser device described in item 1 of the f-range, wherein the complex grating period of the dead condition is used to set the optical parameter—optical optics, which uses a non-linear optical system. A 唁 -linear 风 wind oscillator (0PO) produces a narrow-frequency laser 'which is broken ^ back to V (the part has a dispersion / Β) grating structure formed by the light refraction effect, so that at least the optical parameters are mixed Multi-wavelength laser vibration chirps are formed in the frequency of —: U). # I 2 device, which uses a non-linear optical element, + false ~ ----- ~~~~ —-— j 200410464 6. The scope of patent application is long. 7. A laser device which uses a non-linear optical element to generate a narrow-frequency laser through an optical parameter oscillator (0P0), wherein the non-linear optical element has a dispersion type formed by a light refraction effect A Bragg reflector (DBR) structure whereby at least one wavelength of the optical parameter mixing is oscillated. 8. The laser device according to item 6 or 7 of the scope of the patent application, wherein the decentralized feedback (DFB) structure or the decentralized Bragg reflector (081) structure has eight corpses 111 and / 211 that satisfy the Prague condition. A spatial periodicity Λ g, where η is the equivalent refractive index seen at the Bragg wavelength λ, and m is a positive integer, so that the laser device can vibrate at the wavelength λ. 9. If applying for a patent The laser device according to item 6 or 7 of the scope, wherein the Bragg wavelength 1 is an arbitrary wavelength of these non-linear mixed wavelengths. 10. The laser according to item 1, 6, or 7 of the patent application scope Device, wherein the non-linear optical element is a non-linear optical crystal with a second-order non-linear optical coefficient. 1 1. The laser device according to item 6 of the scope of patent application, wherein the optical parameter oscillator (OP0) It is inside a single nonlinear crystal and has a decentralized feedback (DFB) structure with a photorefractive effect. 1 2. The laser device according to item 6 of the patent application scope, wherein the optical parameter oscillator (OP0 Non-linearity Inside the crystal, there is a decentralized feedback (D F Β) structure with a photorefractive effect. 1 3. The laser device according to item 7 of the scope of patent application, wherein the light Page 33 200410464 VI. Scope of patent application The scientific parameter oscillator (0P0) is located inside a single nonlinear crystal and has a decentralized Bragg reflector (DBR) structure with light refraction effect. 1 4 · The laser device according to item 7 in the scope of the patent application, wherein the optical parameter oscillator (OP0) is inside a waveguide nonlinear crystal and has a decentralized Bragg reflector (DBR) with a light refraction effect. structure. 15 · The laser device according to item 10 of the scope of patent application, wherein the non-linear optical element is a birefringent phase-matching nonlinear optical crystal. 16 · The laser device according to item 10 in the scope of patent application, wherein the non-linear optical element is a quasi-phase-matched nonlinear optical crystal. 17. The laser device according to item 10 of the scope of patent application, wherein the second-order nonlinear optical crystal system is a photorefractive effect nonlinear optical crystal, which is selected from the following material groups, including: niobic acid The above-mentioned crystals of lithium, lithium button acid, and impurity doped. 1 8. A laser device using a non-linear optical element to generate a narrow-frequency laser through an optical parameter oscillator (0P0), wherein the non-linear optical element has a dispersion formed by a light refraction effect A Bragg reflector (DBR) structure or a decentralized Bragg reflector (DBR) structure, and wherein the fabrication of the optical refractive index variation is irradiating a light beam so that the light beam penetrates a photomask above the non-linear optical element. 19. The laser device according to item 18 in the scope of the patent application, wherein the photomask has a specific grating design. After the light beam is irradiated, an oscillator matching the optical parameter is generated after the photomask ( OP0) Spatial light intensity changes under Bragg conditions. 20. The laser device according to item 18 of the scope of patent application, wherein the light Page 34 200410464 VI. Scope of patent application The beam is an optical writing beam, which has the effect of inducing space charge induced in the non-linear optical material of the light refraction effect. 2 1. The laser device according to item 18 of the scope of patent application, wherein the light beam is located at one of the wavelengths of visible light or ultraviolet (UV) wavelength. 22. The laser device according to item 18 of the scope of patent application, wherein the non-linear optical element is a non-linear optical crystal having a second-order non-linear optical coefficient. 2 3. A laser device using a non-linear optical element to generate a narrow-frequency laser through an optical parameter oscillator (0P0), wherein the non-linear optical element has a dispersion formed by a light refraction effect Feedback structure (DFB) structure or decentralized Bragg reflector (DBR) structure, and wherein the optical refractive index change is made using an interference optical refraction effect writing method, thereby having two crossed mines with an appropriate angle The light beam can generate interference fringes through the interference effect, thereby generating spatial optical intensity modulation in the non-linear optical element. 24. The laser device as described in item 23 of the scope of the patent application, wherein the periodicity of the interference fringes is matched to the Prague conditions desired for the operation of the optical parameter oscillator (OP0). 2 5. A laser device that uses an electro-optical non-linear optical element to generate a narrow-frequency laser through an optical parameter oscillator (OP0), wherein the electro-optical non-linear optical element has an electro-optic effect A distributed feedback (DFB) structure, and wherein a spatially modulated electric field is applied to the electro-optic non-linear optical element, whereby a refractive index along the laser transmission direction is periodically modulated in space, and the refractive index Modulation Periodic System Page 35 200410464 VI. Scope of patent application The Prague conditions that are expected to be operated by this optical parameter oscillator (0P0). 2 6 · A laser device using an electro-optic nonlinear optical element to generate a narrow-frequency laser through an optical parameter oscillator (OP0), wherein the electro-optic nonlinear optical element has an electro-optic effect A distributed Bragg reflector (DBR) grating, and wherein a spatially modulated electric field is applied to the electro-optic non-linear optical element, whereby a refractive index along the laser transmission direction is periodically modulated in space, and the The periodicity of the refractive index modulation is matched to the Bragg condition expected for the operation of the optical parameter oscillator (OP0). 2 7 · —A laser device that generates a narrow-frequency laser through an optical parameter oscillator (OP0). The optical parameter oscillator has a distributed feedback (DFB) structure on the surface of a nonlinear optical waveguide. Therefore, the optical remineralization of the dispersed Bragg electromagnetic waves that dissipate waves on the surface of the waveguide is sufficient to start the optical parameter vibration. 28. The laser device according to item 27 in the scope of the patent application, wherein the distributed feedback (DFB) structure is manufactured by a method selected from the group consisting of material etching, ion implantation , Film coating, lithography process, and combinations thereof. 2 9 · —A laser device which generates a laser with a narrow bandwidth through an optical parameter oscillator (OP0). The optical parameter oscillator has a decentralized Bragg reflector (DBR) on the surface of a non-linear optical waveguide. ) Structure, by which the optical feedback of the dispersed Bragg electromagnetic wave that dissipates waves on the surface of the waveguide is sufficient to start the optical parameter oscillation. 200410464 VI. Patent application scope 3 〇 The laser device described in item 29 of the patent application scope, wherein the decentralized Bragg reflector (DBR) structure is manufactured using the following groups of methods, including: materials # 刻, material implantation, thin film overlay, lithography process, and combinations thereof. 3 1 · —A laser device that generates a narrow-frequency laser via an optical parameter oscillator (0P0), which has a distributed feedback (DFB) structure or a The distributed Bragg reflector (DBR) structure, whereby the optical feedback of the dispersed Bragg electromagnetic waves inside the waveguide is sufficient to start the optical parameter oscillation. 32. The laser device according to item 31 of the scope of patent application, wherein one of the distributed feedback (DFB) structure and the distributed Bragg reflector (DBR) structure is a type of light refraction effect. 3 3. The laser device according to item 31 of the scope of patent application, wherein one of the distributed feedback (DFB) structure or the distributed Bragg reflector (DBR) structure belongs to an electro-optic effect type. 34. The laser device as described in item 31 of the scope of the patent application, wherein one of the distributed feedback (DFB) structure and the distributed Bragg reflector (DBR) structure utilizes one selected from the following groups: Method for making, including: thermal infiltration, ion implantation, lithography process, and combinations thereof Page 37