Optical fiber for improved performance in S-, C- and L-bands
View Patent ↗An improved optical fiber design has been found to exhibit a relatively low attenuation at the wavelength of 1385 nm (the “water peak”), allowing for Raman amplification to be efficient and effective at wavelengths in the S-band range of 1460 to 1530 nm. An ultra-dry process is used to mate an inner core rod (core plus surrounding trench) with a cladding tube (ring region plus cladding layers) and provide a water peak loss on the order of 0.325 dB/km. The low water peak is combined with appropriate dispersion values and zero dispersion wavelength to form a fiber that supports transmission and Raman amplification in the S-, C- and L-bands of interest for optical transmission systems.
1. An optical WDM transmission system using Raman amplification, said system comprising:
a length of optical fiber including a core region;
an optical transmitter for introducing a lightwave information signal into the optical fiber, the lightwave information signal including separate signal channels operating at at least three separate wavelengths, wavelength division multiplexed (WMD) to form the lightwave information signal;
an optical pump source for introducing optical energy into the core region of said optical fiber, whereby the optical pump energy interacts with the lightwave information signal to produce Raman amplification of said lightwave information signal, wherein the invention is characterized in that the optical fiber has the following properties:
low water peak at 1385 nm less than 0.4 dB/km;
zero dispersion wavelength (ZDW) less than or equal to 1355 nm, with only one ZDW across the entire transmission band from 1310 to 1625 nm;
chromatic dispersion (D) greater than 1 ps/nm-km at 1375 nm and between about 7.5 and about 9.5 ps/nm-km 1550 nm; and
an effective area in the range of 50 to 65 μm 2 at 1550 nm.
2. The system as defined in claim 1 wherein the optical fiber comprises an inner, high index core region and a surrounding, lower index trench region, a ring region surrounding said lower index trench region, a depressed cladding region and an outer cladding region formed to surround said ring region.
3. The system as defined in claim 1 wherein the optical fiber has a low water peak loss at 1385 nm of less than 0.35 dB/km.
4. The system as defined in claim 3 wherein the optical fiber comprises an inner, high index core region and a surrounding, lower index trench region, a ring region surrounding said lower index trench region, a depressed cladding region and an outer cladding region formed to surround said ring region.
5. An optical fiber characterized by:
low water peak at 1385 nm less than 0.4 dB/km;
zero dispersion wavelength (ZDW) less than or equal to 1355 nm, with only one ZDW across the entire transmission band from 1310 to 1625 nm;
chromatic dispersion (D) greater than 1 ps/nm-km at 1375 nm and between about 7.5 and about 9.5 ps/nm-km at 1550 nm; and
an effective area in the range of 50 to 65 μm 2 at 1550 nm.
6. The optical fiber as defined by claim 5 wherein the fiber comprises an inner, high index core region and a surrounding, lower index trench region, a ring region surrounding said lower index trench region, a depressed cladding region and an outer cladding region formed to surround said ring region.
7. The optical fiber as defined by claim 5 with a low water peak at 1385 n less than 0.35 dB/km.
8. The optical fiber as defined by claim 7 wherein the fiber comprises an inner, high index core region and a surrounding, lower index trench region, a ring region surrounding said lower index trench region, a depressed cladding region and an outer cladding region formed to surround said ring region.