公开(公告)号：US20100067099A1

公开(公告)日：2010-03-18

申请号：US12619455

申请日：2009-11-16

申请人： Youichi AKASAKA ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi AKASAKA ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H01S3/30 ,  H01S3/00

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-1)-th and (n-2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-2)-th and (n-3)-th channels may be multiplexed, thereby forming the pumping light source.

摘要翻译： 根据本发明的拉曼放大器包括使用Fabry-Perot，DFB或DBR型或MOPA的半导体激光器的多个泵浦装置，并且从泵送装置输出的泵浦光具有不同的中心波长，并且相邻中心波长 大于6nm且小于35nm。 根据本发明的光中继器包括上述拉曼放大器，并且用于补偿拉曼放大器在光纤传输线路中的损耗。 在根据本发明的拉曼放大方法中，泵浦光的中心波长越短，所述泵浦光的光功率越高。 在根据本发明的拉曼放大器中，当将一定的泵浦波长定义为第一通道时，并且将第二至第n通道限定为朝向较长波长侧以大约1THz的间隔布置，泵浦灯 具有对应于第一至第n通道的波长的多路复用，并且将具有与第n个信道间隔开2波长或更长的波长朝向较长波长侧的波长的泵浦光与多路复用光组合，从而形成泵浦 光源。 具有与第（n-1）和（n-2）通道以外的通道对应的波长的泵浦光可以被多路复用，从而形成泵浦光源。 具有与第（n-2）和（n-3）通道以外的通道对应的波长的泵浦光可以被多路复用，从而形成泵浦光源。

公开(公告)号：US07692852B2

公开(公告)日：2010-04-06

申请号：US11689352

申请日：2007-03-21

申请人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H04B10/17

CPC分类号： H01S3/302 ,  H01S3/06754 ,  H01S3/06758 ,  H01S3/0912 ,  H01S3/094011 ,  H01S3/094015 ,  H01S3/094096 ,  H01S3/10007 ,  H01S3/10015 ,  H01S3/2375 ,  H01S3/2383 ,  H01S2301/04 ,  H04B10/2916

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-1)-th and (n-2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-2)-th and (n-3)-th channels may be multiplexed, thereby forming the pumping light source.

摘要翻译： 根据本发明的拉曼放大器包括使用Fabry-Perot，DFB或DBR型或MOPA的半导体激光器的多个泵浦装置，并且从泵送装置输出的泵浦光具有不同的中心波长，并且相邻中心波长 大于6nm且小于35nm。 根据本发明的光中继器包括上述拉曼放大器，并且用于补偿拉曼放大器在光纤传输线路中的损耗。 在根据本发明的拉曼放大方法中，泵浦光的中心波长越短，所述泵浦光的光功率越高。 在根据本发明的拉曼放大器中，当将一定的泵浦波长定义为第一通道时，并且将第二至第n通道限定为朝向较长波长侧以大约1THz的间隔布置，泵浦灯 具有对应于第一至第n通道的波长的多路复用，并且将具有与第n个信道间隔开2波长或更长的波长朝向较长波长侧的波长的泵浦光与多路复用光组合，从而形成泵浦 光源。 具有与第（n-1）和（n-2）通道以外的通道对应的波长的泵浦光可以被多路复用，从而形成泵浦光源。 具有与第（n-2）和（n-3）通道以外的通道对应的波长的泵浦光可以被多路复用，从而形成泵浦光源。

公开(公告)号：US07548368B2

公开(公告)日：2009-06-16

申请号：US10824402

申请日：2004-04-15

申请人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H04B10/13 ,  H04B10/17

CPC分类号： H01S3/302 ,  H01S3/06754 ,  H01S3/06758 ,  H01S3/0912 ,  H01S3/094011 ,  H01S3/094015 ,  H01S3/094096 ,  H01S3/10007 ,  H01S3/10015 ,  H01S3/2375 ,  H01S3/2383 ,  H01S2301/04 ,  H04B10/2916

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-1)-th and (n-2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-2)-th and (n-3)-th channels may be multiplexed, thereby forming the pumping light source.

公开(公告)号：US08437074B2

公开(公告)日：2013-05-07

申请号：US13023301

申请日：2011-02-08

申请人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H04B10/17 ,  H01S3/0941 ,  H01S3/13

CPC分类号： H01S3/302 ,  H01S3/06754 ,  H01S3/06758 ,  H01S3/0912 ,  H01S3/094011 ,  H01S3/094015 ,  H01S3/094096 ,  H01S3/10007 ,  H01S3/10015 ,  H01S3/2375 ,  H01S3/2383 ,  H01S2301/04 ,  H04B10/2916

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-1)-th and (n-2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-2)-th and (n-3)-th channels may be multiplexed, thereby forming the pumping light source.

公开(公告)号：US06646787B2

公开(公告)日：2003-11-11

申请号：US10266742

申请日：2002-10-09

申请人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H01S300

CPC分类号： H01S3/302 ,  H01S3/06754 ,  H01S3/06758 ,  H01S3/0912 ,  H01S3/094011 ,  H01S3/094015 ,  H01S3/094096 ,  H01S3/10007 ,  H01S3/10015 ,  H01S3/2375 ,  H01S3/2383 ,  H01S2301/04 ,  H04B10/2916

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-1)-th and (n-2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-2)-th and (n-3)-th channels may be multiplexed, thereby forming the pumping light source.

公开(公告)号：US06501593B2

公开(公告)日：2002-12-31

申请号：US09886211

申请日：2001-06-22

申请人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H01S300

CPC分类号： H01S3/302 ,  H01S3/06754 ,  H01S3/06758 ,  H01S3/0912 ,  H01S3/094011 ,  H01S3/094015 ,  H01S3/094096 ,  H01S3/10007 ,  H01S3/10015 ,  H01S3/2375 ,  H01S3/2383 ,  H01S2301/04 ,  H04B10/2916

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and a pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n−1)-th and (n−2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights have wavelengths corresponding to the channels than (n−2)-th and (n−3)-th channels may be multiplexed, thereby forming the pumping light source.

摘要翻译： 根据本发明的拉曼放大器包括使用Fabry-Perot，DFB或DBR型或MOPA的半导体激光器的多个泵浦装置，并且从泵送装置输出的泵浦光具有不同的中心波长，并且相邻中心波长 大于6nm且小于35nm。 根据本发明的光中继器包括上述拉曼放大器，并且用于补偿拉曼放大器在光纤传输线路中的损耗。 在根据本发明的拉曼放大方法中，泵浦光的中心波长越短，所述泵浦光的光功率越高。 在根据本发明的拉曼放大器中，当将一定的泵浦波长定义为第一通道时，并且将第二至第n通道限定为朝向较长波长侧以大约1THz的间隔布置，泵浦灯 具有与第1〜第n个通道对应的波长被多路复用，并且将具有与第n个通道间隔开2波长以上的波长朝向较长波长侧的波长的泵浦光与复用光结合，从而形成泵浦 光源。 具有与第（n-1）和（n-2）通道以外的通道对应的波长的泵浦光可以被多路复用，从而形成泵浦光源。 泵浦光具有与第（n-2）和第（n-3）个通道相对应的通道的波长可以被多路复用，从而形成泵浦光源。

公开(公告)号：US06292288B1

公开(公告)日：2001-09-18

申请号：US09527748

申请日：2000-03-17

申请人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H01S300

CPC分类号： H01S3/302 ,  H01S3/06754 ,  H01S3/06758 ,  H01S3/0912 ,  H01S3/094011 ,  H01S3/094015 ,  H01S3/094096 ,  H01S3/10007 ,  H01S3/10015 ,  H01S3/2375 ,  H01S3/2383 ,  H01S2301/04 ,  H04B10/2916

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-1)-th and (n-2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-2)-th and (n-3)-th channels may be multiplexed, thereby forming the pumping light source.

摘要翻译： 根据本发明的拉曼放大器包括使用Fabry-Perot，DFB或DBR型或MOPA的半导体激光器的多个泵浦装置，并且从泵送装置输出的泵浦光具有不同的中心波长，并且相邻中心波长 大于6nm且小于35nm。 根据本发明的光中继器包括上述拉曼放大器，并且用于补偿拉曼放大器在光纤传输线路中的损耗。 在根据本发明的拉曼放大方法中，泵浦光的中心波长越短，所述泵浦光的光功率越高。 在根据本发明的拉曼放大器中，当将一定的泵浦波长定义为第一通道时，并且将第二至第n通道限定为朝向较长波长侧以大约1THz的间隔布置，泵浦灯 具有对应于第一至第n通道的波长的多路复用，并且将具有与第n个信道间隔开2波长或更长的波长朝向较长波长侧的波长的泵浦光与多路复用光组合，从而形成泵浦 光源。 具有与第（n-1）和（n-2）通道以外的通道对应的波长的泵浦光可以被多路复用，从而形成泵浦光源。 具有与第（n-2）和（n-3）通道以外的通道对应的波长的泵浦光可以被多路复用，从而形成泵浦光源。

公开(公告)号：US20070247701A1

公开(公告)日：2007-10-25

申请号：US11689352

申请日：2007-03-21

申请人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H01S3/00

CPC分类号： H01S3/302 ,  H01S3/06754 ,  H01S3/06758 ,  H01S3/0912 ,  H01S3/094011 ,  H01S3/094015 ,  H01S3/094096 ,  H01S3/10007 ,  H01S3/10015 ,  H01S3/2375 ,  H01S3/2383 ,  H01S2301/04 ,  H04B10/2916

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-1)-th and (n-2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n-2)-th and (n-3)-th channels may be multiplexed, thereby forming the pumping light source.

摘要翻译： 根据本发明的拉曼放大器包括使用Fabry-Perot，DFB或DBR型或MOPA的半导体激光器的多个泵浦装置，并且从泵送装置输出的泵浦光具有不同的中心波长，并且相邻中心波长 大于6nm且小于35nm。 根据本发明的光中继器包括上述拉曼放大器，并且用于补偿拉曼放大器在光纤传输线路中的损耗。 在根据本发明的拉曼放大方法中，泵浦光的中心波长越短，所述泵浦光的光功率越高。 在根据本发明的拉曼放大器中，当将一定的泵浦波长定义为第一通道时，并且将第二至第n通道限定为朝向较长波长侧以大约1THz的间隔布置，泵浦灯 具有对应于第一至第n通道的波长的多路复用，并且将具有与第n个信道间隔开2波长或更长的波长朝向较长波长侧的波长的泵浦光与多路复用光组合，从而形成泵浦 光源。 具有与第（n-1）和（n-2）通道以外的通道对应的波长的泵浦光可以被多路复用，从而形成泵浦光源。 具有与第（n-2）和（n-3）通道以外的通道对应的波长的泵浦光可以被多路复用，从而形成泵浦光源。

公开(公告)号：US06775057B2

公开(公告)日：2004-08-10

申请号：US10120173

申请日：2002-04-11

申请人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H01S300

CPC分类号： H01S3/302 ,  H01S3/06754 ,  H01S3/06758 ,  H01S3/0912 ,  H01S3/094011 ,  H01S3/094015 ,  H01S3/094096 ,  H01S3/10007 ,  H01S3/10015 ,  H01S3/2375 ,  H01S3/2383 ,  H01S2301/04 ,  H04B10/2916

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n−1)-th and (n−2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n−2)-th and (n−3)-th channels may be multiplexed, thereby forming the pumping light source.

公开(公告)号：US06654162B2

公开(公告)日：2003-11-25

申请号：US09886212

申请日：2001-06-22

申请人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

发明人： Youichi Akasaka ,  Yoshihiro Emori ,  Shu Namiki

IPC分类号： H01S330

CPC分类号： H01S3/302 ,  H01S3/06754 ,  H01S3/06758 ,  H01S3/0912 ,  H01S3/094011 ,  H01S3/094015 ,  H01S3/094096 ,  H01S3/10007 ,  H01S3/10015 ,  H01S3/2375 ,  H01S3/2383 ,  H01S2301/04 ,  H04B10/2916

摘要： A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light. In the Raman amplifier according to the present invention, when a certain pumping wavelength is defined as a first channel, and second to n-th channels are defined to be arranged with an interval of about 1 THz toward a longer wavelength side, the pumping lights having wavelengths corresponding to the first to n-th channels are multiplexed, and an pumping light having a wavelength spaced apart from the n-th channel by 2 THz or more toward the longer wavelength side is combined with the multiplexed light, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n−1)-th and (n−2)-th channels may be multiplexed, thereby forming the pumping light source. The pumping lights having wavelengths corresponding to the channels other than (n−2)-th and (n−3)-th channels may be multiplexed, thereby forming the pumping light source.