TW201027154A - Optical transmission/reception module - Google Patents

Abstract

An optical transmission/reception module which can ensure the transmission quality without providing a collimating optical device and a narrow-band filter. A fiber (7) with a grating which has a function of the narrow-band filter to block transmission of an optical signal in a band other than a narrow band containing a wavelength of 1310 nm, a narrow band containing a wavelength of 1490 nm, and a narrow band containing a wavelength of 1550 nm is used as an optical fiber for transmitting an optical signal with the wavelength of 1310 nm that has passed through WDM filters (4, 5) to a station and transmitting optical signals with the wavelengths of 1490 nm and 1550 nm transmitted from the station to the WDM filter (5).

Description

201027154 VI. Description of the Invention: [Technical Field] The present invention relates to an optical transceiver module, and more particularly to a GE-P0N (on a network service that uses an optical fiber to provide a maximum transmission speed of 1 Gbit/s for a subscriber) Gigabit Ethernet-Passive Optical Network System) In the optical fiber terminal device (0ptical Ne1: w〇rk Unit, 〇NU), the optical transceiver module for processing the conversion of optical signals and electrical signals. Stomach [Prior Art] The GE-P0N system is a splitter that is installed in the central office by the Optical Line Terminal (0LT), which divides the transmission path into a maximum of 32, and is placed in the subscriber's home. The optical fiber terminal device is composed of. The data/sound signal transmitted by the central office fiber optic terminal device to the subscriber end fiber optic terminal device is allocated to the wavelength of 149 nm, and the downstream analog image is assigned to the wavelength of 155 Onm. On the other hand, the subscriber data terminal device transmits the uplink data signal transmitted to the central office fiber optic terminal device to a wavelength of 131 。. In this way, the GE-P0N system uses a Wavelength Division Multiplexing (WDM) technology capable of dividing a complex wavelength to perform one-core bidirectional optical communication. However, in the GE-P0N system, a guard band must be set in the optical wavelength band of the downlink data/sound signal and analog image signal. That is to say, in order to avoid transmission and reception of optical wavelengths other than the above-mentioned optical wavelength band, it is necessary to use an optical communication module in which a guard band is set by adding a 2108-10361-PF 3 201027154 optical fiber terminal device. As described above, it is necessary to use a subscriber-side optical fiber terminal device to set a frequency-protected optical communication module. For example, in the transceiver module disclosed in Patent Document 1, the WDM filter is used to solve the multiplexed optical signal of the complex wavelength. The two-way light of the heart is 彳§. However, in this transceiver module, only the optical components are mirror-connected between the 泸, the waver and the optical fiber, and are not suitable for the GE-P0N to be set in the vicinity of the optical wavelength of the downlink data/sound signal and the analog image signal. In the system. Fig. 14 is an explanatory diagram of filter characteristics formed by the divergence light of the transceiver module disclosed in Patent Document 1. The rectangular portion of Figure 14 shows the specifications. As shown in Fig. 14, in the case where a divergent light is incident on a narrowband filter inside the optical transceiver module of the subscriber fiber terminal device, the divergent light of the optical transceiver module passes through the guard band (wavelength band; Ι1_α). . When the field wavelength of the data and sound signals and or analog image signals is #, the filter characteristics of the narrow-band chopper will change depending on the angle of the incident light to the narrow-band filter, so it is necessary to keep it narrow. The filter characteristics of the band filter and ensure the transmission quality. To maintain the filtering characteristics of the narrow-band f filter and ensure the transmission quality, it is preferable to set a collimator that converts the divergent light of the optical fiber into parallel light, and adjust the angle of the incident light to the narrow-band filter. For example, the transceiver device disclosed in Patent Document 2 is provided with a narrowband filter and a collimator. Figure 15 is a parallel light of the transceiver module disclosed in Patent Document 2.

2108-10361-PF 4 201027154 An illustration of the characteristics of the resulting filter. The rectangular portion of Fig. 15 indicates the specifications. As shown in Fig. 15, the guard band ' of the wavelength band (also ι_α), and 丄 ν Λ I + α ) can avoid transmission and reception of unnecessary light wavelengths. Further, in Patent Document 3, the structure in which the oblique fiber grating is combined with the non-tilted fiber grating is disclosed as low reflection and 4 〇 dB is transmitted through the μ * Α upper 鬲.

Lost filter. It is not easy to obtain low reflection and high penetration loss of φ 40dB or more using only slanted fiber gratings. However, it is generally considered that combining oblique fiber gratings with non-tilting fiber gratings with a transmission loss of about 2 〇 dB can achieve low reflection and 40 dB. Above high penetration loss characteristics. The structure of the optical transceiver module using the optical fiber filter as described above is not described here. Patent Document 1: Japanese Laid-Open Patent Publication No. 2003-524789 (Patent 2) A Patent Document 2: JP-A-2005-26022A (Polony [Just 9], [0010], 4th)) Patent Document 3: Licensed 36 丨 〇 【 【 【 【 【 【 【 【 【 发明 发明 发明 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 The structure described thus sets the characteristics of the collimator and ensures the quality of the transfer wheel. However, it is difficult to miniaturize, and the material of the part material uses oblique fiber light because of the conventional filtering using fiber grating.

2108-10361-PF 5 201027154 Peach to obtain a 20 dB high Bragg reflection wavelength band or low reflection characteristics. In order to solve the above problem, the present invention solves the above problems without providing a collimator or a wave, and further obtains an optical transceiver module capable of securing the transported product f. "As the optical signal of the first wavelength band that will be transmitted by the split-wave multiplexer is transmitted to the central office, it will be lighted by A, and will be lighted by the 帛2 and 3rd wavelengths developed by the central office. The signal is transmitted to the nine-fiber device of the split-wave multiplexing device of the split-wave multiplexing device, and the optical transceiver module of the present invention uses optical signal penetration preventing the i-th, second, and flute, and the second and third wavelength bands. The narrow-band filter function of the grating fiber. According to the invention, the device transmits the optical signal of the "long" strip to the central office by the split-multiplexing device, and the second and the second end are sent by the central office. The optical signal of the third wavelength band is transmitted to the optical fiber device of the split-wave multiplexing device, and the optical transceiver module uses a grating fiber having a function of a narrow-band filter that blocks the penetration of optical signals other than the 帛i, the second and third wavelength bands. However, due to the above composition, the present invention does not require a collimator or a narrow-band filter, and can ensure the quality of the transmission, thereby achieving the object of miniaturization and reduction of the material of the part. [Embodiment] Embodiment 1 FIG. Shown according to embodiment 1 of the present invention The optical transceiver module shown in Figure 1 is mounted on the add-on and eight-end fiber optic terminal devices. In Figure 1, the transmitting module converts the upstream data electrical signals into 2108-10361-PF 6 201027154 1310ηπι wavelength optical signal, and then the optical wavelength is rotated to the WDM filter 4. The receiving module 2 is the first receiving module, and receives the downlink data/sound generated by the WM filter 4. The 149 Onm wavelength optical signal (including the optical signal of the second wavelength band) is then converted into an electrical signal by the optical signal. The receiving module 3 is the second receiving module 'received by the receiving WDM filter 5 Analogous image 1 550nm wavelength optical signal (including the third wavelength band optical signal) and then 'convert the optical signal into an electrical signal. Φ Figure 1 shows the light of the first wavelength band transmitted by the transmitting module 1. The signal is 1 31 〇nm. The optical signal of the second wavelength band received by the receiving module 2 is 149〇11111. The optical signal of the third wavelength band received by the receiving module 3 is 155〇11111, but the above is only an example. The first, second and third wavelength bands may also be other wavelength bands. The wave filter 4 is a first wavelength division multiplexing filter, and the optical signal of the wavelength 1310 nm outputted by the transmitting module 1 is penetrated to the 5 end of the wdm filter; on the one hand, the wavelength of the WDM filter 5 is penetrated by U90 nm. The optical signal φ is reflected to the receiving module 2. The WDM 泸 and the waver 5 are the second multiplexed multiplex filter, which penetrates the WDM; the optical signal of the wavelength of 1310 nm of the filter 4 penetrates to the optical fiber. The connector 6 (f iber ferrule) end, at the same time, the optical connector 6 outputs an optical signal with a wavelength of 14 g 〇 nm to the WDM filter 4 end; on the one hand, the optical connector 6 outputs an optical signal having a wavelength of I550 nm to be received. Module 3. The WDM reducers 4, 5 constitute the entire split multiplexer. The optical fiber connector 6 is a housing member for accommodating the optical fiber 7 and is provided on the right side of the adjacent WDM filter 5 in Fig. 1 . 2108-10361-PF 7 201027154 The grating fiber 7 transmits an optical signal that penetrates the wavelength 131 Onni of the WDM filter 5 to the output of the connector 8 and transmits the wavelength of 1490 nm and 155 入射 incident from the end of the connector 8 on the other hand. The optical signal of nm (the optical signal transmitted by the central office) is output to the WDM filter 5 terminal. The grating fiber 7 has a narrow band (the second wavelength band) including the wavelength 1310 ηη, a 乍 frequency ττ (the second wavelength band) including the wavelength U9 〇 nm, and a band other than the narrow band (the third wavelength band) having a wavelength of 1550 nm. The function of a narrow band filter that the light signal penetrates. The connector 8 is the only connecting part that connects one end of the grating fiber 7 and is connected to one end of a single mode fiber. The other end of the single mode fiber is connected to the central end fiber optic terminal device. Next, the operation of the optical transceiver module according to the first embodiment will be described. Initially, the operation of the optical transceiver module in the subscriber end fiber optic terminal device to transmit the uplink data signal to the central office fiber optic terminal device will be described. After receiving the electrical signal of the uplink data, the transmitting module 1 converts the electrical signal into an optical signal having a wavelength of 1310 mn and outputs the optical signal to the WDM filter 4. The WDM filter 4 accepts the slave transmit module! After the light signal of the wavelength of 131〇, the light signal is transmitted to the end of the WM filter 5 . The WDM filter 5 will pass the optical signal of the wavelength 13 〇 (10) which penetrates the ffDM filter 4 to the end of the optical fiber connector 6. Since an optical signal having a wavelength of 131 〇 nm is incident on the optical fiber connector 6, the optical signal of the wavelength UlOriin is transmitted in the grating optical fiber 7 and is emitted from the connector 8 toward the single mode optical fiber. Next, the optical transceiver module in the subscriber end fiber optic terminal device will be described.

2108-10361-PF 8 201027154 Receiving downlink data/sound signals and analog image signals The downlink data/sound signals transmitted by the central office fiber optic terminal devices are optical signals with a wavelength of 1490 nm, and the descending analog image signals are light with a wavelength of ι 55 〇. The signals, the two optical signals are transmitted in a single mode fiber and incident on the connector 8. Then, an optical signal having a wavelength of 1490 nm and 1 550 nm is transmitted through the grating fiber 7 to be emitted from the optical connector 6 to the WDM filter 5. The WDM filter 5 receives the optical signal of the wavelength 149〇nm and ^1550nm transmitted from the grating fiber 6, and then separates the optical signal of the wavelength ΗΘΟηιη and the optical signal of the wavelength of 1550 nm, and transmits the optical signal of the wavelength of 1490 nm to the wdm filter 4. The optical signal with a wavelength of 1550 nm is reflected to the end of the receiving module 3. The receiving module 3 receives the optical signal of the wavelength 155 〇rm transmitted from the WDM filter 5, and converts the optical signal having a wavelength of 1550 nm into an electrical signal, and outputs a downlink analog video signal of the electrical signal. The WDM filter and waver 4 reflects the optical signal of the wavelength of 1490 nm which penetrates the WDM filter 5 to the receiving module 2 end. • The receiving module 2 receives the optical signal of the wavelength i49 〇 nm from the WDM filter 4, converts the optical signal having a wavelength of 1490 nm into an electrical signal, and outputs a downlink data/sound signal of the electrical signal. Here, the grating fiber 7 changes the refractive index of the refractive index which is increased by the ultraviolet light after being irradiated to the optical fiber. That is to say, after the grating optical fiber 7 is irradiated to the optical fiber by ultraviolet light, a core or a cladding of the optical fiber forms a grating, and the refractive index changes periodically. For the above reasons, the grating fiber 7 can reflect only the specific wavelength of light corresponding to the period 2108-10361-PF 9 201027154, and therefore the grating fiber 7 is used as a fiber device having an optical filter (narrow band tear wave) function. ~ Since the grating light 7 can form the grating non-destructively directly in the optical fiber, it can be manufactured at low cost. Moreover, since it is possible to easily change the optical characteristics such as the center wavelength, the bandwidth, and the reflectance, it has the advantages of low loss, miniaturization, and high reliability. The grating fiber 7 installed in the optical transceiver module of Fig. 1 penetrates a narrow-band optical signal having a wavelength of 1310 nin, a narrow-band optical signal having a wavelength of ι49 〇 ηπ, and a narrow-band optical signal having a wavelength of 1550 nm, but The optical wavelengths of the bands other than the above three narrow bands are attenuated, and the grating fiber 7 has such a narrow band filter function. Therefore, it is not necessary to have a narrow band filter inside like a conventional optical transceiver module. Also, since it is not necessary to convert the wavelength of light from divergent light to parallel light, it is not necessary to configure the collimator like a conventional optical transceiver module. The grating fiber 7 can also diffuse a narrow-band optical signal having a wavelength of 1310 nm, a narrow-band optical signal having a wavelength of 190 nm, and a band optical signal having a wavelength other than a narrow band of 155 〇ηπι from the core to the outer casing to ensure reflection failure. Decrease. Fig. 2 is an explanatory view showing the characteristics of the fiber grating. As shown in Fig. 2, the narrowband filter and the collimator are not provided. In the GE-pon system with the wavelength band (λΐ-α) and (λΗα) protection band, the required wavelength of light can be avoided. Send and receive. The rectangular portion in Figure 2 indicates the specifications. According to the embodiment 1 as described above, the wavelength 131 Omn optical signal transmitted through the WDM filter 4, 5 2108-10361-PF 10 201027154 is transmitted while transmitting the optical signals of the wavelengths M90 nm and 155 〇 nm from the central office. To the fiber at the end of the filter 5, the fiber is used to block (make it) a narrow-band optical signal having a wavelength of 131 〇 nm, a narrow-band optical signal having a wavelength of 1490 nm, and a band light other than a narrow band having a wavelength of 155 〇 nm. The narrow-band filter function of the grating fiber 7 through which the signal is transmitted is constructed. Therefore, it is not necessary to provide a narrow-band filter and a collimator, and the monthly b is sufficient to ensure the transmission quality, and finally the miniaturization and the reduction of the cost of the parts and materials are achieved. Embodiment 2 FIG. 3 is a view showing the configuration of an optical transceiver module according to Embodiment 2 of the present invention. In the third embodiment, the same reference numerals are given to the same parts as those in the description of the embodiment i, and the description thereof will be omitted. The grating fiber connector 9 houses a grating portion corresponding to the grating fiber 7 in Fig. 1. One end of the optical fiber 10 is connected to the grating optical fiber housed in the grating optical fiber connector 9, and transmits an optical signal of a wavelength 1310 ηη which penetrates the WDM filter 5, and outputs it to the connector 8 end; An optical signal of 1490 nm and 1 550 nm (an optical signal transmitted by the central office) having an incident end at the 8th end is output to the WDM filter 5 terminal. In the first embodiment described above, the grating optical fiber 7 is connected between the optical fiber connector 6 and the connector 8, and the grating length of the grating optical fiber 7 is shortened by the refractive index change, and the grating portion is housed in the optical fiber connector 6. Example 2. The details are as follows. In addition, focusing on the magnification change of the refractive index by n times, the third figure can be

The grating length of the optical fiber connector 9 in 2108-10361-PF 11 201027154 is shortened by 1/π 2 times. This feature grating fiber connector 9 rasterizes the optical fiber core in the fiber connector. In this way, the excess length processing space of the optical fiber can be reduced, that is, the length of the optical fiber 10 can be shortened, so that the subscriber-side optical fiber terminal device can save space. Due to the shortened fiber length, the goal of material cost reduction can also be achieved. Therefore, the optical transceiver module of the second embodiment can achieve a smaller size and a lower cost of parts and materials than the optical transceiver module of the embodiment. Embodiment 3 Fig. 4 is a view showing the configuration of an optical transceiver module according to Embodiment 3 of the present invention. In the fourth drawing, the same reference numerals are given to the same parts as those in the i-th and third figures, and the description thereof is omitted here. The grating connector 11 houses a grating portion corresponding to the grating fiber 7 in the second drawing. In the first embodiment, the grating optical fiber 7 is connected between the optical fiber connector 6 and the connector 8. Since the optical length of the optical fiber 7 is shortened by the refractive index change, the grating portion is housed in the connector 8. Example 3. The details are as follows. In addition, focusing on the magnification of the refractive index change by a factor of two, the grating length of the grating connector U in Fig. 4 can be shortened to 1/w2 times. This feature 'grating connector U is set to let the inner core of the connector The rasterized part. In this way, the excess length of the fiber can be reduced, so the add-in fiber optic terminal can save space. Due to the short length of the fiber length 2108-10361-ρρ 201027154, the goal of material cost reduction can also be achieved. Therefore, the optical transceiver module of the third embodiment can achieve a smaller size and lower cost of parts and materials than the optical transceiver module of the first embodiment. Embodiment 4 Fig. 5 is a view showing the configuration of an optical transceiver module according to Embodiment 4 of the present invention. In the fifth drawing, the same reference numerals as those in the first embodiment denote the same portions, and the description thereof will be omitted. The grating receptacle 12 is an optical module component disposed on the right side of the WDM filter 5 in FIG. 5, connected to one end of the single-mode fiber, and has an optical axis function and an external connection with the optical module. The structure of the connected device. The grating socket 12 houses a grating portion corresponding to the grating fiber 7 in the first drawing. In the above-described first embodiment, the grating optical fiber 7 is connected between the optical fiber connector 6 and the connector 8, and since the grating length of the grating optical fiber 7 is shortened by the refractive index change, the grating portion is housed in the socket. . The specific description is as follows. Further, by enlarging the refractive index change amount by n times, the grating length of the grating socket 12 in Fig. 5 can be shortened to 1/«2 times, and the grating socket 12 rasterizes the optical fiber core in the socket. In this way, the excess length processing space of the optical fiber can be reduced, so that the adder-side optical fiber terminal device can save space. Due to the shortening of the length of the fiber, the goal of material cost reduction can also be achieved. Therefore, the optical transceiver module of the fourth embodiment can achieve the effect of miniaturization and reduction in the cost of parts and materials compared to the light receiving module of the first embodiment of the optical transceiver 2108-10361-pf 13 201027154. Embodiment 5 and Fig. 6 are explanatory diagrams showing the composition of a fiber grating for an optical transceiver module according to Embodiment 5 of the present invention. As shown in Fig. 6, the outer casing 14 covers the core 13 in a cylindrical shape, and the core 13 has an inclined fiber grating portion 15 and a stray light attenuation fiber portion 16°. In the embodiment 5, the inclined fiber grating is used as the wavelength 遽. Waves. First, a method of fabricating the oblique fiber grating portion 15 will be described below. Fiber gratings are fabricated by exposing the fibers to ultraviolet light. The fiber used is preferably /, connected to the outside (connector 8 end (refer to the figure), the incident end of the light penetration) to the optical fiber between the optical transceiver module in the core diameter, numerical aperture (numericai aperture), etc. Optical properties are of an interchangeable type. If the optical characteristics are not interchangeable, when the optical transceiver module or the external optical fiber is connected through a fiber connector or the like, a loss of connection occurs and a signal is deteriorated. In this embodiment, the quartz glass-based optical fiber (the quartz glass casing and the added Ge (germanium core)) generally used for the photo-chancement is not used, and the light in which the sensitivity is added by adding Ge and B (butterfly) is used. Induction fiber. Specifically, the outer casing is also quartz glass, and the core is added with B. The mode field diameter, the numerical aperture, and the outer diameter of the casing are the same as that of the external single mode fiber. The mode field diameter is About 10 ym, the numerical aperture is 〇· 13 # m, and the outer diameter is 125 # m. In order to increase the sensitivity before the fiber grating exposure, after treatment for 2 weeks in high-pressure hydrogen gas (1 Torr atmosphere), a Nd-YAG laser (output power 2108-10361-PF 14 201027154 200 mW, wavelength 266 nm) was irradiated to form a grating. Exposure lasers are best used with a quasi-molecular laser (eXCinierlaser). The portion that illuminates the ultraviolet light first removes the protective layer of the optical fiber to expose it to the outer casing, exposing it in a state close to the phase mask. The phase mask is adjusted to a period in which the wavelength of 55 k/m is the Bragg wavelength, and the mask period configuration sets the tilt of the angle of the vertical line with the direction in which the fiber extends. 0 is formulated at -90. ~90. In the range. In the oblique fiber grating portion 15, a wavelength end shorter than the Bragg wavelength causes a penetration loss called a casing mode. Under a uniformly uniform grating, the loss of the outer casing mode creates a periodic comb-like spectrum, and under the chirped grating with periodic variations in the grating, the spectral shape is averaged to form a broad spectrum. To illustrate the optical characteristics of the fiber grating, we use an example of the spectrum measurement of the oblique fiber grating portion 15 in the seventh circle. The fiber grating is etched using light-induced light, and the phase mask is tilted by about 3. The grating length is 5 coffee, and the amount of germanium is 0.4 nm. Figure 7 shows the penetration loss and the reflection spectrum. The Bragg reflection exists at a wavelength of 1556 nm to 1557 nm, and since the tilt angle is adjusted to a condition that Bragg reflection is reduced, the reflection intensity is a value smaller than -30 dB. Since the reflection intensity is very small, the spectrum of the penetration loss in the above wavelength does not have a structure. The loss occurring at the wavelength end shorter than the 1553 nm in the transmission loss spectrum is caused by the above-described housing mode. Because of the flaws in the grating fiber, the comb-like spectral structure is averaged. The loss around 1 555 nm is the spectral structure caused by the reflection of the basic transmission mode to the higher order LP11 mode, also known as the ghost line grating. In the fiber before exposure, this mode has a large loss of transmission and does not occur in the spectrum structure 2108-10361-PF 15 201027154. With the light thumb exposure, the average refractive index of the core is increased, and the transmission loss is reduced. 7 shows a change to ^ loss π bucket · Lu stop ^ a eight teeth through the loss. Because the LP11 loose type is in the unexposed fiber area c ^ ^ ^ I, it is generally considered that the reflection intensity does not become large, but because of the 夯, ή is the effect of the uneven reflection of the grating and there is residual reflection. occur. Appeared in the 7th

The structure of the reflection intensity of about 1 554 nm to 1 555 M is the result of the above-mentioned residual. Since the Bragg reflection intensity and the penetration loss of the shell mode and the ghost line grating vary depending on the tilt angle, it is necessary to adjust the tilt of the mask during exposure in order to obtain the desired characteristics. In particular, the Bragg reflection has a dependent property that is sensitive to the tilt angle of the grating. The longer the length of the fiber grating, the greater the refractive index change caused by the exposure, the greater the penetration loss, but the refractive index change caused by the exposure will have a certain upper limit due to the characteristics of the fiber used. Therefore, in order to obtain the desired penetration loss, it is first assumed that the inherently suitable refractive index changes over the fiber to be used, and then the exposure is performed in consideration of the grating length required to obtain the necessary penetration loss. To be used in the GE-P0N optical transceiver module, the characteristics of the wavelength filter must be the wavelength λ A in the wavelength band 131 〇 nm, the wavelength λ b used in the 1490 nm band, and the wavelength used in the 155Onm band. The loss is small, the protection band near the wavelength of use (eg wavelength band λ C-α ) has a large loss through ' and has a lower reflection at these wavelengths. 5。 The grating length is 50mm, the grating tilt angle is 4.5. In the case where the refractive index change due to exposure is 2 χΚΓ 3, the transmission reflection spectrum (calculation result) of the fiber grating is shown in Fig. 8. 2108-10361-PF 16 201027154 To achieve the required penetration loss wavelength (eg 1.5 nm), use a chorus grating. The difference between the maximum and minimum values of the Bragg wavelength of the fiber grating, that is, the amount of 啁啾 is set to 2.7 nm. Further, in order to reduce the reflection, it is assumed that a portion of both ends of the grating is subjected to an apodization process in which the amount of change in refractive index is gradually reduced.

From Fig. 8, it can be confirmed that the use wavelength is 1 552 ηι; the 1C penetration loss is small, and the transmission band (wavelength band λ C- α ) at the wavelength end shorter than the use wavelength has a penetration loss of 4 〇 dB or more (refer to 8a圊), the reflection intensity is small (refer to Figure 8b), and it is known that the calculation meets the required specifications. Since the grating tilt in the core of the fiber is about 145 times the tilt angle of the mask, the tilt angle of the mask is set at 31 degrees. However, when the penetration spectrum of the fiber grating was actually measured, the stray light generated in the grating portion was found to be transmitted in the casing portion, so that the penetration loss was reduced. For such problems, we use the outer casing to transmit light in the fiber protective layer interface, and find a way to avoid the penetration loss by providing a portion of the fiber grating at the end of the fiber grating. However, it is necessary to obtain a penetration of 4 〇άβ or more: after measurement, it is confirmed that it is preferable to provide a fiber portion for stray light attenuation. Fig. 9 shows the results of the penetration loss measured by changing the length of the fiber portion 16 for the astigmatism for the same oblique fiber grating portion. It is known from the ninth circle that a penetration loss of 4 〇 (10) or more is obtained, and at least a fiber light portion 16 for the stray light attenuation of 16 cm or more is provided. Preferably, the stray light attenuation is as described above. Therefore, the inclined fiber grating portion 15 for the optical transceiver module for the GE-P0N is attached with a length of 16 cm for the optical fiber portion 16. With regard to the reflection characteristics, a test to change the tilt angle was confirmed.

2108-10361-PF 17 201027154 The reflection intensity near the 1 is extremely small. Good low reflection characteristics can be obtained by adjusting the most suitable tilt angle and light average exposure. According to the fiber grating described in the above embodiment, the necessary wavelength characteristics can be obtained in the wavelength range of the optical transceiver module for the GE-P0N, so that the operations described in the first embodiment and the third embodiment can be realized. The space saving of the subscriber end fiber optic terminal device is achieved. Example 6

Fig. 1 is a view showing the configuration of a fiber optic peach for an optical transceiver module according to a sixth embodiment of the present invention. As shown in Fig. 10, in the present embodiment, a fiber grating is used, and the oblique fiber optical portion 17a (the first grating fiber group) and the non-tilting fiber grating portion 17b (the second grating fiber group) are used. The same reference numerals as in the sixth embodiment denote the same portions, and the description thereof will be omitted. The same optical sensing fiber as in Embodiment 5 is used for the optical fiber. The individual grating characteristics will be explained below.

The connecting inclined fiber grating portion 17a is produced by a penetration of 12._ or more caused by a small angle of inclination of the Bragg reflection and a casing mode. Further, the non-tilted fiber grating portion m for connection is a cycle in which a lattice reflection is generated at a wavelength of the outer casing mode in which the oblique fiber grating portions 17a Μ μ, +, kh Μ 连结 are connected, and the central system is manufactured to be close to the link. The position of the optical fiber portion 17a is inclined. For the connection, the slanting fiber grating portion i 7 is connected to the non-tilted fiber grating portion > the knives and the stray light reduction fiber portion are sequentially connected. Far surname build, use oblique fiber grating part 1 7a ^

2108-10361-PF 18 201027154 External (connector 8 end (refer to j may be exposed separately, there is also a phase reticle exposed together, but - light. Fig.)) One end of the connection. The respective gratings can be reduced in cost by using the corresponding two forms. The non-tilted fiber grating portion Hb for the exposure connection has a wavelength band with high reflection intensity caused by Bragg reflection, and the center wavelength of the wavelength band is Prague wavelength. The wave loss of the connecting oblique fiber grating portion na is large, and the reflection wavelength band of the connecting non-tilted fiber peach portion claws can be included. Therefore, the non-tilted fiber grating portion for connection which is seen by the external end can be reduced. 17b Bragg reflection intensity. If the wavelength of the transmission loss of the connecting oblique fiber grating portion 17a is small in the Bragg reflection wavelength band of the non-tilting fiber grating portion 17b for connection, the reflection intensity of this wavelength from the outer end is increased. As described above, in the state where the Bragg reflection intensity of the non-tilted fiber grating φ portion 1 ? b for connection for the connection viewed from the external end is reduced, the penetration of the all-fiber grating is lost in the non-tilted fiber grating portion 丨 7b for connection. The Bragg reflection wavelength band is particularly increased, so that as the wavelength filter used in the optical transceiver module, the penetration blocking wavelength range is preferably included in the above-mentioned Bragg wavelength band. In the case where the penetration prevention wavelength range is wide, the wavelength range can be enlarged by deuterating the mask. As a relative relationship of the wavelength positions, the penetration loss due to the outer casing pattern is generated at a wavelength shorter than the Bragg reflection, and the penetration preventing wavelength (the piercing reflection included in the non-tilted fiber grating portion 17b for connection) is formed. The transmission loss wavelength band is disposed at a wavelength end shorter than the Bragg wavelength band of the connection oblique fiber grating portion 2108-10361-PF 19 201027154 minutes 17a, and does not allow the Bragg reflection at the ratio (4) fiber grating portion 4 i7a (four) Lager wavelength The wavelength end of the strip produces 'as a' to reduce the Bragg reflection intensity of the non-tilted fiber grating portion 17b for connection seen from the outer end. Since the Bragg intensity of the oblique fiber grating (4) 17a is adjusted by adjusting the inclination angle of the salt J, it is possible to obtain a wavelength reducer characteristic having a small reflection intensity at all wavelengths. "

In the desired penetration preventing wavelength range, the light penetration loss of the oblique fiber grating portion na for connection and the light transmission loss of the optical portion 11b of the non-tilting fiber for connection are respectively L1 (dB), L2 ( When expressed in dB), "Llh2.5' L1+L2 "G" (the third condition) must be satisfied. Further, in the above-mentioned penetration preventing wavelength range and the oblique grating reflectance in the Bragg wavelength band of the oblique grating, respectively, m(10), R2(10), and when the reflectance of the non-tilted grating in the penetration blocking wavelength range is expressed by RO (dB), it is necessary to Satisfy the following formula (1) (2nd condition) - Ill _ / iU + 2Il

L〇l〇gp〇-+l〇—]^25) ^^_25 (] satisfies the above first and second conditions while simultaneously adjusting the tilt angle, period, and noise of the tilted grating of the connected tilted fiber grating portion l7a With the length of the fiber 4 minutes, the light penetration of the filter in the above-mentioned penetration-preventing wavelength range is achieved. The penetration of the light is less than 40 dB and the reflectance of the full band is below -25 dB. In other words, even the surname Tian Hao, ° with the inclined fiber grating portion 17 7a length 45mm, the connection non-tilt also, the fiber grating portion 17b length 1 〇 min, phase

2108-10361-PF 20 201027154 Cover tilt angle 3". ...The amount of 2.7 brewing, refractive index change, illusion, and apodization, and the calculation results of the connected fiber grating characteristics under such conditions are shown in the 11th. We can see that any of the penetration loss (refer to the Ua diagram) and the reflection (refer to the f Ub diagram) satisfy the above conditions. The apodization process is a 6th-order super Gaussian distribution, but it can also be a 2nd or 4th order super Gaussian distribution.

In Figure 11a, the 1 550 band can be seen with a wavelength width of 2 nm _4 〇 dB.

The above large penetration loss is caused by Bragg reflection of the optical portion m of the non-tilted fiber as described above. On the other hand, the wide penetration loss from this wavelength band to the short wavelength end is caused by the loss of the outer casing mode of the slanted fiber grating portion 17a, and the relative position of the wavelength positions of the two optical arms. As mentioned earlier. In the two types of reflection bands of the 155 〇 (10) band which can be seen in Fig. u, the short-wavelength end is the Bragg reflection of the optical portion b of the non-tilted fiber for connection, and the outer mode mode penetration loss of the inclined yoke grating portion na is Reduce the result. The Bragg reflection intensity at the long wavelength end of the coupled oblique fiber grating portion i7a is reduced by the adjustment of the tilt angle. The fiber grating of such a connection structure has a shorter length of the fiber and a higher penetration loss for the same refractive index change amount than the inclined fiber grating of the type described in the fifth embodiment, and thus has a relatively easy manufacturing effect. . Further, the amount of erbium per unit length of the slanted grating can be made larger, so that the effect of obtaining the low reflection characteristic is easier. The fiber grating described in the above embodiment is used in the optical transceiver module for the GE-P0N. The necessary wavelengths can be obtained in the wavelength field

With the characteristics of 2108-10361-PF 201027154, it is possible to realize the space saving of the subscriber-side optical fiber terminal device as described in the first embodiment and the third embodiment. Embodiment 7 Fig. 12 is a view showing the configuration of a fiber grating according to an embodiment of the present invention. For the first transmission and reception group, as shown in Fig. 2, the sound of the beginning of the sound is too long. 1... Fiber grating, the type of use:: the gate is used to connect the second oblique grating portion = 1 type of grating fiber group) The structure in which the non-tilted fiber coffee type 2 grating fiber group is connected. Therefore, the inclined grating exhibits a joint structure of the two inclined first gate portions 18a, 18b. The same reference numerals as those in Fig. 6 or Fig. 10 denote the same portions, and the description thereof will be omitted. = The same optical sensing fiber as in Example 5 and the implementation was used. The individual grating characteristics will be explained below. The inclined fiber portion is formed by connecting the ith oblique peach portion (the first (inclination) grating) with a small inclination angle of Bragg reflection, and tilting the connected oblique grating portion 18b (second (tilted) grating) Corner again. In the first optical thumb and the second grating, the overlap of the transmission loss wavelength is achieved in the same period and the same (four) amount, but the cis F plus BraggG plus ing) of the 帛i grating is reduced. The amount of unit length increases. In this way, the reflectance of the first grating can be made smaller than the reflectance of the second grating. The non-tilting fiber grating portion 17b for connection and the fiber portion for stray light attenuation were produced by the method of Example 6. The non-tilted fiber grating h 17b for connection (non-tilted grating) is a period in which a Bragg reflection is generated at a wavelength loss of the above-mentioned casing mode 2108^1 361-Pp 22 201027154 of the oblique grating, and is formed in the approaching oblique grating portion 18b. s position. Finally, the connection is made by connecting the y1 oblique light thumb portion 18a, the second inclined grating portion m for connection, the non-tilting fiber grating portion 17b for connection, and the stray light attenuation fiber portion 16. The first inclined grating portion for connection > 18a is one end that is connected to the outside. Individual gratings may be exposed separately. It is also possible to use the corresponding two

The phase mask formed by the form is exposed, but the __like preference can reduce the exposure of the cost together. The light penetration loss of the first oblique grating, the light transmission loss of the second oblique grating, and the light penetration loss of the non-tilted grating are L11 (dB) and L21, respectively, in a desired penetration preventing wavelength range. When dB) and L2 (dB) are expressed, "L1122.5, L11+L21212.5, L2 215" (third condition) must be satisfied. The first blocking grating light reflectance in the above-described penetration preventing wavelength range and the Bragg wavelength band of the first oblique grating is expressed by β11 ((1Β), R12 (dB), respectively; and Bragg reflection in the non-tilted grating is caused by When the penetration loss wavelength band and the second oblique grating light reflectance in the Bragg wavelength band of the i-th and second oblique gratings are expressed by R21 (dB) and R22 (dB), respectively, the following (2) must be satisfied. Equation and (3) (4th condition). ^11 R21+2L11 R0+2LU+2L2\ lOlogJlO^+10——f +1(Γ—~ϊό—~]幺一25 ...(2) R12 R22 lOlogPOi+lcT^]幺-25 (3) 2108-10361-PF 23 201027154 The above-mentioned third and fourth conditions are satisfied, and the length of the grating tilt angle, the period, and the stray light attenuation fiber can be adjusted. The minimum light penetration loss of the optical filter penetrating the wave-blocking range is above 4 DdB and the reflectance of the full-wavelength band is -25 dB or less. For example, the length i of the first inclined grating portion 18a for connection is 〇 Mm, the length of the second inclined grating portion 18b for connection 35 mm, and the length of the non-tilted fiber grating portion 17b for connection 1 Omm, phase reticle tilt angle 3 丨, 啾 2 2. 7 rm, refractive index change 1.2 χΗΓ 3, the same apodization treatment as in Example 6 can be used to obtain penetration loss and reflection. The fiber grating of such a connection structure is easier to obtain low reflection characteristics and easier to manufacture than the two types of oblique fiber gratings described in Embodiment 6. This is because the reflection characteristics of the entire wavelength filter are considered. In this case, the first oblique grating can increase the amount of enthalpy per unit length of the oblique grating, so that low reflection can be achieved, and the reflection contribution by the second oblique grating is caused by the penetration loss of the first oblique grating. In order to be in the vicinity of the penetration blocking wavelength range, the grating as seen from the external end has low reflection characteristics, and the penetration loss wavelength range of the oblique grating near the outer end must include the reflection wavelength range of the inclined grating at the inner end. The larger the amount per unit length, the easier it is to get a low-reflection grating' but the penetration loss is also reduced. The tilting grating near the outer end adjusts the total amount of light to make the transmission loss wavelength range above the reflection wavelength range of the inclined grating at the inner end, adjust the amount of enthalpy per unit length and the length of the fiber grating to have the effect of reducing the reflection on the LDB. Obvious penetration

2108-10361-PF 201027154 Loss, also adjusts the wavelength position so that the transmission loss wavelength range includes the reflection wavelength range of the inclined grating at the inner end. By the above methods, it is possible to obtain a low reflection characteristic of the entire grating viewed from the external end. Further, in order to reduce the reflection of the wavelength of the penetration loss of the inclined grating at the outermost end, for example, the following method is used. As shown in Fig. 7, since the transmission loss wavelength and the reflection wavelength are substantially the same wavelength, for example, the Bragg wavelength band of the first oblique grating and the Bragg wavelength φ band of the second oblique grating are set at the same wavelength position, The total amount of tilting grating is set to be higher than the total amount of scattering of the second oblique light, and the Bragg wavelength band of the first oblique grating includes the Bragg wavelength band of the second oblique grating, so that the first oblique grating penetrates. The loss wavelength band can include the reflection wavelength band of the second oblique grating, and the entire grating viewed from the external end can have low reflection characteristics. When the multiplexing of the grating is tilted like this, if the multiplex is increased from the two couplings, the effect of lowering the reflection characteristics can be easily obtained. At this time, it is preferable to set the same (4) for each oblique light (4) and increase the amount of dispersion per unit length of the inclined grating near the external connection end so that the total amount is equal to or higher than the above. According to the fiber grating described in the above embodiment, the necessary wavelength characteristics can be obtained in the wavelength range of the optical transceiver module for the GE-P0N. Thus, the embodiment can be realized! In the operation described in the third embodiment, the space saving of the subscriber end fiber terminal device is achieved. Embodiment 8 FIG. 13 is a diagram showing an optical transceiver module according to Embodiment 8 of the present invention.

2108-10361-PF 25 201027154 FBG production diagram. The fiber grating is made of ultraviolet light, but since the ultraviolet light passing through the phase mask penetrates the surface of the fiber casing, the angle of inclination of the structure exposed in the fiber is actually 1.45 times that of the phase mask. Due to the cylindrical light collecting effect of the outer casing, the optical structure of the light has a non-uniformity. In this embodiment, as shown in Fig. 13(a), the optical fiber (core 13, outer casing 14) is filled with ultraviolet light penetrating liquid enthalpy, and ultraviolet light is irradiated by exposure. Exposure through the phase mask 2 〇. For example, when water is used to irradiate the ultraviolet light 21 for exposure, the refractive effect of the surface of the outer casing 14 is lowered because the refractive index of water is close to the refractive index of the outer casing of the optical fiber. Finally, the structural tilt angle of the actual exposure in the fiber will be about U times that of the phase light sheet 20. The adjustment accuracy of the tilt angle of the phase mask 2 会 is 由 机械 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨 丨In this case, the accuracy of the structural tilt angle of the actual exposure in the light can be improved. In this case, you can improve 30. / Degree accuracy. To obtain low reflection (4), the tilt angle must be adjusted to the desired size. If the angle is deviated, the Bragg reflection will increase. Therefore, improving the angle accuracy will result in low reflection characteristics and easy production. The same angle accuracy improvement effect is as shown in Fig. 13(b), in which the optical fiber (core 13, casing 14) is provided in the groove portion 23g on the groove-shaped dielectric plate 23, and the phase mask is transmitted through the exposure ultraviolet light 21 for exposure. 2 〇 exposure derived. For example, using a quartz glass plate with a groove as a grooved dielectric plate

In the case of 2108-10361-PF 201027154 23, since there is no difference in refractive index from the outer casing of the optical fiber, no refraction of light is generated on the surface of the outer casing. Finally, the actual exposure structure in the fiber will have the same tilt angle as the phase mask, and the accuracy of the grating angle can be further improved. The groove portion 2 3g provided on the groove-shaped dielectric plate 23 does not need to have the same shape as that of the optical fiber case, and the same result can be obtained even if the v-shaped groove is easily formed. According to the fiber grating described in the above embodiment, the necessary wavelength characteristics can be obtained in the wavelength range of the optical transceiver module for the GE-P0N, so that the operations described in the first embodiment and the third embodiment can be realized. And to achieve space saving of the subscriber end fiber optic terminal device. The present invention has been described in detail above, but the above description is not an example in all cases, and the present invention is not limited thereto. It is also contemplated that other variant embodiments of the examples are not described in this specification without departing from the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing the composition of an optical transceiver module according to Embodiment 1 of the present invention. Fig. 2 is an explanatory view showing the characteristics of the fiber grating. Fig. 3 is a view showing the configuration of an optical transceiver module according to a second embodiment of the present invention. Fig. 4 is a view showing the configuration of an optical transceiver module according to a third embodiment of the present invention. Fig. 5 is a view showing the configuration of an optical transceiver module according to a fourth embodiment of the present invention. 2108-10361-PF 27 201027154 Fig. 6 is an explanatory diagram showing the composition of a fiber grating for an optical transceiver module according to Embodiment 5 of the present invention. Figure 7 shows the penetration loss and reflection spectrum. Figure 8a shows the plot of transmittance versus wavelength under a set condition. Figure 8b shows the reflection attenuation versus wavelength curve under a set condition. Fig. 9 is a graph showing the penetration loss measured by changing the length of the stray light attenuation fiber portion for the same oblique fiber grating portion. Fig. 10 is a view showing the configuration of a fiber grating for an optical transceiver module according to a sixth embodiment of the present invention. Figure 11a shows the plot of transmittance versus wavelength under a set condition. The lib diagram shows the reflection attenuation versus wavelength curve under a set condition. Fig. 12 is a view showing the configuration of a fiber grating for an optical transceiver module according to a seventh embodiment of the present invention. Fig. 13 is a view showing the fabrication of a fiber grating for an optical transceiver module according to Embodiment 8 of the present invention. Fig. 14 is an explanatory view showing the characteristics of the filter formed by the divergent light of the transceiver module disclosed in the patent document. Fig. 15 is an explanatory diagram showing the characteristics of the filter formed by the parallel light of the transceiver module disclosed in Patent Document 2. 2~ receiving module; [main component symbol description] 1~ sending module;

2108-10361-PF 201027154 3~ receiving module; 5~¥DM filter; 4~WDM filter 6~optical connector 7~grating fiber; 8~ connector; 9~grating fiber connector; 10~ fiber ; 11 ~ grating connector; 1 3 ~ core; 1 5 ~ inclined light woven grating part; 12 ~ grating socket; 14 ~ housing, 16 ~ stray light attenuation with fiber part

17a to slanted optical woven first grating portion; Hb ～ non-tilting optical fiber first grating portion 18&~ connecting first inclined grating portion; 18b to connecting second oblique grating portion; 19~ dielectric plate; 21~ Exposure to ultraviolet light; 23~ grooved dielectric plate; 20~ phase mask; 22~ ultraviolet light penetrating liquid; 2 3 g ~ groove. 2108-10361-pp 29

Claims (1)

201027154 VII. Patent application scope: 1. The optical transceiver module has a transmitting/receiving module that transmits or receives a specific wavelength of =, and an optical fiber optically connected to the transmitting/receiving module to transmit optical signals. There must be a penetration blocking wavelength range in the vicinity of the above-mentioned wavelength of use. The optical transceiver module includes: an inclined grating fiber portion (15, m, 18a, 18b) having a grating inclined to a vertical line in the conveying direction, so that the above-mentioned penetration The penetration loss is above the μ value, and the reflection intensity is below the value of the long dry fiber stray light attenuation fiber portion (16) for attenuating the stray light transmitted to the outer casing of the optical fiber, wherein the optical transceiver module is The oblique grating fiber portion is optically connected to the optical fiber portion for the light attenuation, the oblique grating fiber portion is formed at an incident end of the transmitted light, and the stray light attenuation fiber portion is formed at an exit end of the transmitted light. 2. The optical transceiver module of claim 1, wherein the optical fiber further comprises an optical connection between the oblique grating fiber portion and the stray light attenuation fiber portion, and has a grating substantially perpendicular to the transmission direction. Vertical grating fiber section (17b). 3. The optical transceiver module according to claim 2, wherein the oblique grating fiber portion is formed by a chirped grating, wherein the vertical grating fiber portion has a transmission loss wavelength band formed by Bragg reflection, and is included in the wearing The above-mentioned penetration preventing wavelength range of the transmission loss wavelength band is set at a wavelength end shorter than the Bragg wavelength band of the oblique grating fiber, so that the wavelength of the fabric is 2108-10361~pF 30 201027154 » longer than the oblique grating fiber portion The wavelength end does not produce Bragg reflection. 4. The optical transceiver module according to claim 2, wherein the oblique grating fiber portion is formed by the first oblique grating fiber portion and the second oblique grating fiber portion (18a, 18b) in the light incident end. The amount of yangk per unit length of the first inclined grating fiber portion is larger than the amount of enthalpy per unit length of the second inclined grating fiber portion, and the penetration loss wavelength band of the first oblique grating fiber portion • Reflected wavelength band containing the second oblique grating fiber portion. 5. The optical transceiver module according to claim 3, wherein the tilt angle, the period of the grating, and the length of the fiber portion for the stray light attenuation are adjusted according to the following conditions, including: The wavelength range is blocked, and the light transmission loss of the inclined grating fiber portion and the light penetration loss of the vertical grating fiber portion are expressed by L1 (dB) and L2 (dB), respectively, satisfying "l1>12 5, U+L224 ( In the above-mentioned penetration preventing wavelength range and the Bragg wavelength band of the oblique grating optical fiber portion, the reflectance of the oblique grating fiber portion is expressed by R1 (dB) and R2 (dB), respectively, in the above-mentioned penetration. When the reflectance of the above-mentioned vertical grating fiber portion of the blocking wavelength range is expressed by R 〇 (dB), the following formula (1) is satisfied. Rl R0+2U 101〇邰0, 10~1^-25, 心一25 ... (1) 6. The optical transceiver module according to claim 4, wherein the grating has an inclination angle, a period, a volume, and And the length of the fiber portion for the stray light attenuation is adjusted according to the following conditions, including: 2108-10361-PF 31 201027154 In the above-mentioned penetration prevention wavelength range, VU ^ light penetration of the first oblique grating fiber portion Loss, Bu # I. AK X, the light penetration loss of the second oblique grating fiber portion of the mussel and the light penetration loss of the vertical grating fiber portion are respectively represented by (1)(10))' L21(dB)' L2(dB), and '(1)& 5, L11+L21 >12.5, L2215", · The light reflectance of the ith slant grating fiber portion of the above-mentioned ith oblique grating fiber band in the above-mentioned penetration preventing wavelength range and the Bragg wavelength band at the ith oblique optical fiber portion, respectively R11 (dB), R12 (dB); a penetration loss wavelength band formed by Bragg reflection in the vertical grating fiber portion and the second oblique grating fiber in a Bragg wavelength band of the i-th and second oblique grating fiber portions When the partial light reflectance is expressed by R21 (dB) or R22 (dB), the following formula and formula (3) must be satisfied. -R21+2Z11 R0+2L\ 1+2Z21 101og|10 ]〇+1〇10 +10 i〇1 幺一25 R12 R22 — ...(2) HHogPO 10+l〇i|f25 ...(3) 7· — An optical transceiver module having a transmitting/receiving module for transmitting or receiving an optical signal of a specific wavelength of use, an optical fiber optically connected to the transmitting/receiving module and transmitting an optical signal' must have a penetration preventing wavelength near the above-mentioned use wavelength The optical transceiver module includes: at least one grating fiber portion (15, 17a, 17b, 18a, 18b) having a grating such that a penetration loss in the above-mentioned penetration blocking wavelength range is above a predetermined value; The optical fiber portion (16) is configured to attenuate the stray light transmitted to the outer casing of the optical fiber 2108-10361-PF 32 201027154 « ', wherein the optical transceiver module is optically connected to the optical fiber portion of the stray light reduction portion by the grating optical fiber portion The grating fiber portion is formed at an incident end of the transmitted light. The portion of the stray light attenuation fiber is formed at an exit end of the transmitted light. 2108-10361-PF 33