公开(公告)号：US5113459C1

公开(公告)日：2001-10-23

申请号：US64714191

申请日：1991-01-29

Applicant: PIRELLI CAVI SPA

Inventor： GRASSO GIORGIO ,  TAMBURELLO MARIO

IPC: H04J14/00 ,  H04B10/00 ,  H04J14/02 ,  G02B6/28

CPC classification number: H04B10/291 ,  H04B10/0777 ,  H04B2210/078 ,  H04J14/0226 ,  H04J14/0246 ,  H04J14/025 ,  H04J14/028

公开(公告)号：JPH03166782A

公开(公告)日：1991-07-18

申请号：JP29350790

申请日：1990-10-30

Applicant: PIRELLI CAVI SPA

Inventor： GRASSO GIORGIO ,  RIGHETTI ALDO ,  FONTANA FLAVIO

IPC: G02F1/35 ,  H01S3/06 ,  H01S3/07 ,  H01S3/0915 ,  H01S3/094 ,  H01S3/10 ,  H01S3/17 ,  H01S3/30 ,  H04B10/12

Abstract: PURPOSE: To reduce noise by setting the length of an active fiber to be one which is directly equivalent to the partial absorption of in put pumping light and containing a selection mirror element, in which light is reflected by a pumping wavelength and light is transmitted by a communication wavelength for the downstream of the active fiber. CONSTITUTION: A dichroic coupler 2, a pumping laser 3, and the active fiber 6 are contained, and a selective (or dichroic) mirror element 8 is provided on the downstream of the active fiber 6. A pumping wavelength (p) is reflected, and a communication wavelength (p) is made to pass through without changing it. A communication fiber 7 connected to the output of the mirror element 8 transports an amplified signal and makes communication with a target place. Noise which is guided to a communication line from an amplifier is decreased, and the quality in communication signal is improved.

公开(公告)号：JPH04298724A

公开(公告)日：1992-10-22

申请号：JP1896991

申请日：1991-02-12

Applicant: PIRELLI CAVI SPA

Inventor： GRASSO GIORGIO ,  RIGHETTI ALDO

IPC: G02B6/00 ,  G02B6/28 ,  G02F1/35 ,  G02F1/39 ,  H01P1/16 ,  H01S3/06 ,  H01S3/067 ,  H01S3/07 ,  H01S3/08 ,  H01S3/094 ,  H01S3/10 ,  H01S3/108 ,  H01S3/16 ,  H04B10/17

Abstract: PURPOSE: To provide an amplifier for making the light emission force of transmission signals and pumping light emission force present in the almost same distribution inside the cross section of an active fiber and be centralized in a fiber area where a fluorescent dopant is present as well. CONSTITUTION: This amplifier is composed of the active fiber 7 containing the fluorescent dopant inside respective optical cores provided with radiation at the wavelength of transmission signals to be amplified and light emission pumping signals are inputted into the optical fibers. In this case, the active optical fiber 7 is in an almost linear shape, performs the optical propagation of a single mode at a transmission wavelength and the optical propagation of multiple modes at a pumping wavelength and is arranged in the bend shape 11 of a bend radius corresponding to the propagation into the fiber itself in only a basic mode at the pumping wavelength in a length larger than 70% of the length. Thus, the fiber for reducing a mode diameter at the transmission wavelength without transmitting the high mode of the pumping signals is attained.

公开(公告)号：JPH0787026A

公开(公告)日：1995-03-31

申请号：JP994791

申请日：1991-01-30

Applicant: PIRELLI CAVI SPA

Inventor： GRASSO GIORGIO ,  TAMBURELLO MARIO

IPC: H04J14/00 ,  H04B10/00 ,  H04J14/02 ,  H04B10/17 ,  H04B10/16

Abstract: PURPOSE: To provide an optical fiber transmission line capable of injecting and extracting optical transmission signals without converting them to an electric form. CONSTITUTION: This line is provided with a means for injecting and extracting optical service signals to/from the optical fiber 3 of the line. The means is provided with the transmission/reception units 10 of the optical service signals for receiving the service signals from an optical line and transmitting them to the line itself in the form of the optical signals of a wavelength sufficiently different from the wavelength of communication signals. Further, the respective units are connected to photocouplers 9 inserted to the optical fiber for coupling the optical service signals to the line fiber and extracting them from the line fiber.

公开(公告)号：JPH04312988A

公开(公告)日：1992-11-04

申请号：JP589291

申请日：1991-01-22

Applicant: PIRELLI CAVI SPA

Inventor： GRASSO GIORGIO ,  RIGHETTI ALDO ,  MELI FAUSTO

IPC: G02B6/00 ,  G02B6/28 ,  G02F1/35 ,  G02F1/39 ,  H01P1/16 ,  H01S3/06 ,  H01S3/067 ,  H01S3/07 ,  H01S3/094 ,  H01S3/16 ,  H01S3/17 ,  H01S5/00

Abstract: PURPOSE: To improve the quantum efficiency of an optical fiber amplifier. CONSTITUTION: Er2 O3 is doped into a quartz fiber of single mode as a fluorescent doping substance, Al2 O3 is doped as a refractive index modifying dopant for achieving an active optical fiber 8, and dichroic couplers 5 and 13 are passed through it for connecting lasers 7 and 12 for excitation with a wavelength of 980nm. An input signal is introduced from an end of an optical fiber. The input signal is approximately 1550nm, equivalent to the window of the optical fiber, and the excitation wavelength is 980nm that is by for longer than a wavelength near 520nm frequently used conventionally, thus obtaining a high quantum efficiency with is close to the theoretical value, when optimum doping configuration is executed.

公开(公告)号：FI104294B1

公开(公告)日：1999-12-15

申请号：FI910649

申请日：1991-02-11

Applicant: PIRELLI CAVI SPA

Inventor： GRASSO GIORGIO ,  RIGHETTI ALDO

IPC: G02B6/00 ,  G02B6/28 ,  G02F1/35 ,  G02F1/39 ,  H01P1/16 ,  H01S3/06 ,  H01S3/067 ,  H01S3/07 ,  H01S3/08 ,  H01S3/094 ,  H01S3/10 ,  H01S3/108 ,  H01S3/16 ,  H04B10/17 ,  G02B6/24 ,  G02B1/39 ,  G02B3/05 ,  G02B10/12

Abstract: The invention relates to an optical amplifier, in particular for optical-fiber telecommunications lines, comprising an active fiber (7) containing a fluorescent dopant in the respective optical core having emission at the wavelength of the transmission signal to be amplified, into which optical fiber a luminous pumping signal is supplied, in which the active optical fiber (7) is a fiber that in a substantially rectilinear configuration permits the single-mode light propagation at the transmission wavelength and the multi-mode light propagation at the pumping wavelength and is disposed, at least over 70% of the length thereof, in a curved configuration (11) with a bending radius corresponding to the propagation into the fiber itself of the fundamental mode alone at the pumping wavelength, thereby reducing the mode diameter at the transmission wavelength without however transmitting higher modes for the pumping signal.

公开(公告)号：PT97751B

公开(公告)日：1998-12-31

申请号：PT9775191

申请日：1991-05-23

Applicant: PIRELLI CAVI SPA

Inventor： GRASSO GIORGIO ,  RIGHETTI ALDO

IPC: H01S3/067 ,  H04B10/02 ,  H04B10/12 ,  H04B10/135 ,  H04B10/14 ,  H04B10/17 ,  H04B10/18 ,  H04B10/2581 ,  H04B10/16

Abstract: The present invention relates to a optical fiber telecommunication line comprising active-fiber (10) optical amplifiers (5, 6) in which the reflectivity towards the amplifiers' active fiber is limited below a critical value lower by at least 10 dB than the reflectivity due to the Rayleigh scattering within the line fibres; this reflectivity value is obtained by arranging optical isolators (11a, 11b) having a limited inner reflectivity upstream and downstream of the amplifier (6) and by disposing reflection limiting means on all fibres (12) converging towards the amplifier's active fiber (10).

公开(公告)号：ITMI971483A1

公开(公告)日：1998-12-23

申请号：ITMI971483

申请日：1997-06-23

Applicant: PIRELLI CAVI SPA ORA PIRELLI C

Inventor： GRASSO GIORGIO ,  RIGHETTI ALDO

IPC: H04B10/02 ,  H04B3/06 ,  H04B10/18

公开(公告)号：PT95726B

公开(公告)日：1998-07-31

申请号：PT9572690

申请日：1990-10-29

Applicant: PIRELLI CAVI SPA

Inventor： GRASSO GIORGIO ,  RIGHETTI ALDO ,  FONTANA FLAVIO

IPC: H01S3/06 ,  H01S3/07 ,  H01S3/0915 ,  G02F1/35 ,  H01S3/094 ,  H01S3/10 ,  H01S3/17 ,  H01S3/30 ,  H04B10/12

Abstract: The present invention relates to an optical low-noise amplifier (2) of the active-fiber type. containing a laser emitting substance (3) to be connected to an optical telecommunication fiber (1) and receiving light there from at the transmission wavelength, in which the active fiber (6) is also fed from a light source at a pumping wavelength and has a length corresponding to a partial absorption of the pumping light directly input therein, downstream of active fiber (6) a selective mirror element (8) being present which reflects the light at the pumping wavelength and is transparent to the transmission wavelength light; preferably the mirror element (8) consists of an optical demultiplexer (9) adapted to separate the transmission wavelength and the pumping wavelength on two output fibers (11, 12), a mirror (13) reflecting at least the pumping wavelength being present at the end of the fiber (7) carrying the pumping wavelength.

公开(公告)号：PT95724B

公开(公告)日：1998-07-31

申请号：PT9572490

申请日：1990-10-29

Applicant: PIRELLI CAVI SPA

Inventor： GRASSO GIORGIO ,  RIGHETTI ALDO ,  FONTANA FLAVIO

IPC: C03C13/04 ,  G02F1/35 ,  H01S3/06 ,  G02B6/02 ,  H01S3/067 ,  H01S3/07 ,  H01S3/091 ,  H01S3/0915 ,  H01S3/16 ,  H01S3/17 ,  H04B10/12

Abstract: The present invention relates to an optical amplifier, in particular for optical fiber telecommunication lines, operating with a transmission signal in a predetermined wavelength range, which amplifier comprises laser emitting active optical fiber doped with erbium, said fiber contains a further doping substance, distributed along the fiber, said doping substance shows an absorption, for a light having a wavelength lower than 1,540 nm, substantially higher than the absorption that the further doping substance shows for a light having a wavelength varying from 1,540 nm to the superior limit of the predetermined wavelength range of the transmission signal; preferably the further doping substance is samarium. Samarium contained in the fiber is capable of absorbing the spontaneous erbium emission, which would constitute a noise source, allowing a signal to be amplified in a wavelength range substantially corresponding to the tolerance range of the commercially available signal laser emitters.