TW490899B - Method to form fiber device with power equalization - Google Patents

Abstract

The present invention discloses a method to form fiber device with power equalization, which comprises: first, providing a pump laser diode to generate laser light; conducting said laser light into a ratio coupler having specific plural output terminals through an optical isolator; and connecting each output terminal of said ratio coupler to a fiber laser resonant cavity, so that each output terminal can generate a laser output with one wavelength channel, which results in the laser output with all said specific plural output terminals. The present invention is characterized in using the adjustment method of external parameters of resonant cavity for adjusting the laser outputs of the plural wavelength channels to have an equal power.

Description

490899

V. Description of the invention α) Detailed description: Technical field of the invention: The present invention relates to a method for forming a laser light source module, in particular β relates to a method for forming an optical fiber component with equal power. ’疋 背景 Background of the Invention: In response to the rapid expansion of information capacity, the split-wave multiplexing wheel technology has become the mainstream of optical fiber transmission. Optical fiber components—optical fiber lasers—have proven to have extremely narrow line widths (Li new id th) and very small wavelength / temperature drift coefficients (△ λ / 〇 C), which are very suitable as digital and analog transmission light sources. Regarding split-wave multiplexed laser light sources, currently, multiple semiconductor distributed feedback (DFB) lasers are most widely used at the same time. As the transmission speed increases, the requirements for laser light sources are narrow bandwidth, good frequency stability, and The wavelength is accurate, and the output power of the middle and high level. The DBF laser array can be used for multi-channel transmission at the same time, but because it is made on the same base, it is not possible to individually adjust the channels with slightly different wavelengths or optical powers. Considering that the amplified spontaneous emission curve of the fiber laser originated from erbium-doped fiber is uneven, the output signal level may be uneven after each channel of the multi-channel fiber laser is La sing, which will cause the output level between the signal wavelengths. (Power level) and Signal to noise ratio (Signal to noise ratio, SNR) are different, especially after passing through several optical amplifiers, which will obviously degrade the transmission quality. For the selection of multi-channel light sources, previous foreign literatures used separate semiconductor lasers to form multi-channel laser light sources, or produced on the same base.

2. Description of the invention (2) = Guided laser array, or multiple distributed feedback laser arrays in series, or using circular filters in the form of comb filters. For details, please refer to U.S. Patent Nos. 5,91,09 2, 2, 5,524,118, 5,600,6,65, and 5,721,6,5. 】 However, although the above-mentioned foreign literature mentioned the manufacturing method of the multi-channel fiber laser light source, it did not overcome the problem of equalization of power. On the other hand, although academic institutions in China have developed single-channel fiber lasers, they have not yet been used for research and production of multi-channel power sources such as $.

Therefore, the study of power equalization for fiber laser arrays has become a very important subject in academia and industry. Brief description of the invention The main object of the present invention is to provide a method for forming a power equalized optical fiber element. A secondary object of the present invention is to provide a method for forming a laser light source module. Another object of the present invention is to provide a laser light source module.

The invention discloses a method for forming a power equalized optical fiber component. First, an I laser laser is provided to generate laser light. Next, the laser light is introduced into an optical splitter (rat i〇coupler) having a specific plurality of output ends through an optical isolator, and each output end of the optical splitter is connected to An optical fiber laser resonant cavity, so that each output end generates a laser output of one channel, and a total of the laser output of the specific plurality of channels is generated. The importance of the present invention

Page 5 490899 V. Description of the invention (3) The point is to use the parameter adjustment method outside the resonant cavity to adjust the output of the specific multiple channels to equal power. Preferably, the extra-resonant cavity parameter adjustment method is to provide a pump reflection grating outside the cavity of each of the fiber laser resonant cavities, and adopt a reverse calculation method, that is, output the result of the unmodified WDM light source first The optical signal level between channels will be high or low) to find out, so as to adjust the reflectivity of each of the laser reflection gratings so that the laser output powers of the specific plural channels are equal. Preferably, the extra-resonant cavity parameter adjustment method is to provide a pump reflection grating outside the cavity of each of the fiber laser resonant cavities, and adopt a reverse calculation method, that is, output the result of the unmodified WDM light source first ( The optical signal level between channels will be high or low), so as to adjust the center wavelength offset of each of the pumped reflection gratings so that the laser output powers of the specific plural channels are equal. Preferably, the extra-cavity parameter adjustment method is to provide a pumped reflection light tree outside the cavity of each of the fiber laser resonators, using the inverse $ algorithm, that is, outputting the unmodified WDM light source first ( The frequency of the optical signal between channels can be found out, so as to adjust the length of each of the pumped reflection gratings and the erbium-doped fiber so that the laser output powers of the specific plural channels are equal. Drawing number description: w 10-pump laser 20-optical isolator

490899 V. Description of the invention (4) 30- 1 XN optical splitter 40-optical fiber laser resonant cavity The present invention relates to a method for forming a laser light source module, in particular to a method for forming a power equalized optical fiber component . The multi-channel laser light source used for optical fiber communication transmission is currently the most widely used semiconductor distributed feedback (DFB) laser, but its price is slightly more expensive. If you need to specify the wavelength, there is an additional price. Erbium-doped fiber laser, with its specific amplification peak length in the 1550 nm band, can be completely consistent with the working frequency band of erbium-doped fiber amplifiers. Proper design can have narrow frequency and wavelength stability characteristics, in terms of quality Can compete with semiconductor lasers. Optical fiber lasers are placed on both sides of steel: fiber (Erbium-doped fiber, EDF), and fiber gratings with the same reflection center wavelength are placed on the fiber, so that the optical fiber 彳 s generates resonance wavelengths at this two ends (ie, Bragg wavelength). As for the wavelength power, it depends on the pump laser power, the EDF length (L) and the doping Er3 + concentration value, and the reflectance of the paired grating reflectors (R1, R2). Optical fiber laser can be simplified into a two-order laser system (seven w 0 — 1 e v e 1 system) ’At the initial resonance condition, the input conditions are:

Pp + (lp) = Ppo and PASE + (1i) = PS + (1i) = 〇at z = 0 (1) where Ppo represents the input laser power at z = 0, and the laser resonance is described in advance. The following boundary conditions apply : [PS + (li)] n = [PASE- (1 i) + PS- (li)] n-lRo (li) A1 at z = 0 (2) [PS- (1 i)] n = [PASE + ( 1 i) + PS + (li)] n-iRi (li) A2 at z = L (3)

Page 7 490899 V. Description of the invention (5) where η represents the nth iteration value; R 0 (1 i) and R i (1 i) are the reflectances of 1 i at z = 0 and z = L; A1 and A2 are the losses caused by the front and rear fiber grating pairs. Applying the above principles to the actual architecture, it is proposed to use a laser parallel connection of N optical fibers, and then use a suitable coupler or splitter to introduce the pumped laser light into the optical fiber. First, please refer to FIGS. 1A and B, which are structural diagrams of a parallel laser beam splitting optical fiber laser array according to the present invention. Among them, FIG. 1A is a structural diagram of a parallel-pumped split-pumped optical fiber laser array disclosed in the present invention, “Forward pumping, which means that the direction of the pumped laser is the same as that of the multi-channel laser; FIG. 1 B is the architecture diagram of the parallel pumped laser beam splitting optical fiber laser array disclosed in the present invention. "Backward pumping 11 means that the direction of the pumped laser is opposite to the direction of the multi-channel laser. First, a pump laser diode 10 is used to generate a laser ', which passes through an optical isolator 20 and enters a 1XN ratio coupler 30. The N output ends of the 1XN optical splitter 30 are respectively connected to a fiber laser cavity, which are a first fiber laser cavity 40a and a second fiber laser cavity 40b. Wait until the Nth optical fiber laser resonant cavity 40η, wherein the first optical fiber laser resonant cavity 40a is connected to the first output end, the second optical fiber laser resonant cavity 40b is connected to the second output end, and the nth optical fiber laser The radiation cavity 40n is connected to the nth output terminal and so on. In order to ensure the quality of demultiplexing (WDM) transmission, the problem of unequal power between channels must be solved, and the influence of parameters such as pump power and grating reflectance on the power between channels is optimized. Design and Analysis' Because the laser output power is determined by a number of parameters, the calculation is quite complex

490899 V. Description of invention (6) Miscellaneous. To solve the above problem, use the inverse calculation method, that is, first find the output result of the unmodified WDM light source (the optical signal level between channels will be high or low), and then adjust the length of the erbium-doped fiber or the reflectance of the grating (of course, also It can be mixed and adjusted) to flatten the power between channels, in conjunction with experimental or theoretical data, and to fix the same conditions for each production, the commercial specifications (such as the reflectivity of the grating, the length of the erbium-doped fiber, etc.) OK. According to the present invention, pump laser sources are connected in parallel to produce multi-channel power equalized fiber lasers. Assuming that the length of each segment of erbium-doped fiber is the same, and the power given by the pump laser source is the same, the magnitude of the fiber grating laser light power, Because the spontaneous amplified radiation of the erbium-doped fiber is not flat, this gain value is different at each wavelength (for example, the gain value is greater than 1550 0 η at 1532 nm). In this invention we propose adjustment of parameters outside the resonant cavity Method, the final power of each channel depends on three ways: the reflectivity of the pump reflector outside the resonant cavity, the center wavelength translation of the compressible fiber, and the length of the erbium-doped fiber. We try to achieve the purpose of equalizing the channel power by changing the parameters. First, please refer to FIG. 2A. In the first embodiment of the present invention, the reflectivity ({^ 丨 16〇1: ^; ^ 7) Control to achieve power equalization. Because the power output by each fiber laser resonant cavity is different, this embodiment uses the reverse juice nose method, that is, first find the output result of the unmodified WDM light source (the optical signal level between channels will be high or low), By adjusting the reflectivity of the pumped reflection grating of each channel, the laser power output by each channel is equal. The parameters used in this embodiment are erbium-doped concentrations ranging from 2.6, 1 〇24 m-3 to 3.0,

Page 9 490899 V. Description of the invention (7) Between 1024 m-3, the optimal erbium concentration is 2.8, 1024 m-3; spontaneous emission rate is 100 sec-1; optical signal absorption cross section Between 0.5 4, 10-24 m to 0 · 5 6 '1 0-2 4 m, the best optical signal absorption cross section is 0.5 5, 10-24 m2; optical signal emission cross section is 0.4 8' 10-24 m2 to 0.5 2, 10-24 m2, the best optical signal emission cross section is 0.50 '10-24 m2; pump laser absorption cross section is 0.30' 10-24 m2 to 0.32, 10-24 m2 In between, the optimal pump laser absorption cross section is 0.31 '10-24 m2; the left side grating reflectivity of the fiber laser R 0 = 100%; the total pump power is 18 2 m W. For the actual effect of this embodiment, please refer to FIG. 3, where FIG. 3A is a spectrum diagram of an 11-channel fiber laser array without power equalization, and FIG. 3B is a 100% pumped reflection added to each channel The grating is a spectrogram after preliminary adjustment, and FIG. 3C is a spectrogram after power equalization using the technology of the present invention. It can be known from FIG. 3A that the optical fiber laser array without power equalization has the lowest channel 6 and the highest channel 11 with a difference of 7.2 dB. When 100% pumped reflection gratings are added to each channel, it is a preliminary adjustment. The power of each channel generally increases and the power difference decreases by only 1.6 dB, as shown in Figure 3B. After proper adjustment of the fiber grating, the center wavelength reflectance of the pumped reflection grating is between 55% (channel 11) and 100% (channel 6), and the power unevenness of the 11 channels can reach as much as 〇 Below 1 dB, as shown in Figure 3C. Next, please refer to FIG. 2B. In the second embodiment of the present invention, the center wavelength offset of the pump reflectors outside the resonant cavity is controlled for power equalization. Because the power output by each fiber laser resonant cavity is different, this embodiment uses the reverse calculation method, that is, the unmodified WDM light source is output first (the optical signal level between channels will be high)

Page 10 490899 V. Description of the invention (8) With low) Find out, adjust the center wavelength offset of the pumped reflection grating of each channel 'so that the laser power output by each channel is equal. The parameters used in this embodiment are erbium-doped concentrations between 2.6, 1024 m-3 and 3.0, 1024 m-3. The optimal erbium-doped concentration is 2.8 '1024 m-3; spontaneous emission The rate is 100 sec-1. The optical signal absorption cross section is between 0.54 '1〇-24 m to 0 · 5 6 10-24 m, and the best optical signal absorption cross section is 0.55' 10-24 m2; Optical signal emission cross section is between 0.48 '10_24 m2 and 0.52' 10-24 m2, the best optical signal f emission cross section is 0.50 '10-24 m2; pump laser absorption

The cross section is between 0 · 30, 10-24 m2 and 0 · 32 '1 0-24 m2. The optimal pump laser absorption cross section is 0.3 Γ 1 〇- 2 4 m 2; the left grating reflection of the fiber laser The rate Ro = 100%; the total pumped power is 182 mW. Next, please refer to FIG. 2C. In the third embodiment of the present invention, the power of the erbium-doped fiber (EDF length, li) in each channel outside the resonant cavity is controlled for power equalization. Because the power output by each fiber laser resonant cavity is different, this embodiment uses the reverse calculation method, that is, first find the output result of the unmodified WDM light source (the optical signal level between channels will be high or low), and adjust it. The length of the erbium-doped fiber in each channel pumped reflection grating makes the laser power output by each channel equal. The parameter used in this embodiment is that the erbium doping concentration is between 2. β 1 0 2 # m-3 to 3.0 1024 m-3 ’The optimal erbium doping concentration is 2 · g

'1024 m-3; spontaneous emission rate is 100 sec-1; light signal absorption cross section is between 0 · 5 4' 1 0-2 4 m to 0 · 5 6 '1 0-2 4 m, the best light The signal absorption cross section is 0.5 5 '10-24 m2; the light signal emission cross section is between 0.48, 10-2 4 m2 and 〇 52' 10-24 m2, and the optimal light signal emission cross section is 0.55 0 '10-24 m2; cross section of laser absorption between 0.30 and 10-24 m2

Page 11 490899 V. Description of the invention (9) Between 10 and 24 m2, the optimal pump laser absorption cross section is 0.3 Γ: 4 m2; the reflectance of the left grating of the fiber laser R0 = 100. Total pumping The power is 182 mW. The method for forming a power equalized optical fiber element disclosed in the present invention has the following advantages: ^ (1) using a erbium-doped fiber laser to generate a specific amplification wavelength at 1550n_band 'can fully and erbium-doped fiber amplifier optical signal amplification The frequency bands match.

(2) The structure is cheap: using N pairs of fiber gratings with the same reflection wavelength as the reflection surface of the cavity of the fiber laser, it only needs to be pumped with a semiconductor laser of 980111 or U800nm. (3) Small size: Since N fiber gratings can be connected in parallel and only contains a 1 laser, the module is very light. 4 (4) Temperature coefficient is small. · Optical fiber laser with optical fiber as the basic material, the temperature coefficient is only 1/6 of that of semiconductor laser. The wavelength can be accurately controlled and it is not easy to drift. The present invention is described through specific embodiments to illustrate the principles and spirit of the present invention. It should be understood that the present invention is not limited to the specific embodiments disclosed. Therefore, any relevant details made under the principles and scope of the present invention Changes should be regarded as further embodiments of the present invention.

490899 on page 12 Schematic description Schematic description In order to enable the review committee to understand the content of this article more clearly, please refer to the following illustration. Figure 1A is the architecture diagram of the parallel pump laser beam splitting optical fiber laser array disclosed by the present invention. . π forward pumping " means that the direction of the pumped laser is the same as the direction of the multi-channel laser. FIG. 1B is a structural diagram of a parallel pump laser beam splitting optical fiber laser array disclosed in the present invention. "Backward pumping" means that the direction of the pumped laser is opposite to the direction of the multi-channel laser. Figure 2A is the first embodiment of the present invention by controlling the pumped reflection gratings of the channels outside the resonant cavity ( The schematic diagram of the power equalization of the reflectivity of the pump reflect〇r) is shown in Figure 2.B is the central wavelength deviation of the pump reflector in each channel by controlling the channels outside the resonant cavity in the second embodiment of the present invention. Offset for power equalization. Figure 2C is a schematic diagram of power equalization by controlling the length of the erbium-doped fiber (EDF length, li) of each channel outside the resonant cavity in the third embodiment of the present invention. The third is the spectrum diagram of the 11-channel fiber optic laser array of the present invention, of which FIG. 3A is the spectrum diagram of the 11-channel fiber optic laser array without power equalization, and FIG. 3B is that each channel is added with 10 The 0% chestnut reflection grating is a spectrogram after preliminary adjustment ', and FIG. 3C is a spectrogram after power equalization using the technology of the present invention.

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Claims (1)

490899 6. Scope of patent application Patent scope: 1. A method for forming a power equalized fiber optic component, the steps include: a. Providing a series of laser pumps (pump laser diode) to generate laser light; b. The transmitted light is introduced into an optical coupler with a specific plurality of output terminals through an optical isolator (optical isolato) and each output end of the optical divider is connected to an optical fiber mine, respectively. Irradiating a resonant cavity so that each output end generates a laser output of one channel, and the laser output of the specific plurality of channels is counted; and c. Adjust the laser output of the specific plurality of channels to equal power by using the parameter adjustment method outside the resonant cavity. 2 · The method for forming a power equalized optical fiber component according to item 1 of the scope of the patent application, wherein the method for adjusting the parameter outside the resonant cavity is to provide a pumped reflection grating outside the cavity of each of the fiber laser resonant cavity, Adopt the inverse calculation method, that is, first find out the output result of the unmodified WDM light source (the optical signal level between channels will be high or low), so as to adjust the reflectivity of each of the pumped reflection gratings so that the specific complex number The laser output power of each channel is equal. < 1 3 · The method of forming a power equalized optical fiber component as described in the first item of the patent application scope, wherein the method for adjusting the external cavity parameter is to provide a pumping outside the cavity of each of the optical fiber laser resonant cavities The reflection grating adopts the inverse calculation method, that is, the output result of the unmodified WDM light source (the optical signal accuracy between channels) Page 14 490899 VI. There may be low or low in the scope of patent application) Find out, by adjusting the center wavelength offset of each of the pumped reflection gratings, so that the laser output power of the specific plural channels is equal . The square element of the fiber optics is equal to the work of forming iso-rate work. 1¾ Cavity No. 4 is the same as the general rule, please refer to the law, as described in Method 4. Every time the system adjusts the number of parameters, the external inverse is used in the D track. Each grid U 4 complex light> 1 set t every 2 L loses a whole anti-primitive, the pump 1 ^ get D to borrow a W _ to make a confession, and decorate the W degree repair} long. If the cavity is not inferior, there will be a fiber phase cavity first with high optical vibration, that is, there will be work together. Item 1- > Lei Diji pump pump Fan Shuli Institute asked him to make it φ—, ο as long as the 5th power work is formed by the long wave side of the lightning element voxel semi-light fiber -m η ο 8 9 and other shaped items 1— * Lei Dijiyuan pump Fan Shuli Institute asked him to φ-, ο The equivalent power of the fiber of the laser beam is equal to that of the long wave mine body. Part ^ Bian \ Li specifically requested the application of the law of the fiber rate of the piece of power to make the power of the big form is the number of items 1 complex number in the special description of the whole number of fiber rate of light of the rate of work • iL species including its 490899 A laser to generate laser light; an optical isolator whose input end describes the laser; a splitter whose input end is connected to the output end of the optical three-isolator; And has a specific plurality of output ends; a plurality of optical fiber laser resonant cavities, and a wheel-in end of each of the optical fiber laser resonant cavities is connected to one of the output ends of the optical splitter to generate a specific 'complex wave Laser output of a channel; a specific plurality of pumped reflection gratings, wherein each of the pumped reflection gratings is connected to one of the optical fiber laser resonant cavities so that the laser output power of the plurality of channels is equal . For example, the power equalized optical fiber component of item No. 8 of the patent application, wherein the laser is a pump laser. 1 Q. The power equalized optical fiber component according to item 9 of the patent application scope, wherein the pump laser is a semiconductor laser with a wavelength of 980 nm. 1 I The power equalized optical fiber component according to item 8 of the scope of patent application, wherein the pump laser is a semiconductor laser with a wavelength of 1480 nm. 1 2. The power equalized optical fiber component according to item 8 of the scope of the patent application, in which the specific complex number is an integer greater than 3.