Furukawa Releases New Pump Source for Forward Raman Amplifiers


Japan-based Furukawa Electric has developed a new Pump Source FRSi4XX Series for Forward Raman Amplifiers. The Pump Source, as the company reveals in a press release, achieves Higher Speeds and Long-Distance Transmission.

The newly developed pump source will be able to support the rapid increase in communications traffic in recent years. The FRSi4XX Series pump source is a technological innovation in ultrahigh-speed optical fiber communications.

The company developed the new pump sources for Forward Raman amplifiers capable of extending transmission distance while significantly contributing to the advance convenient lifestyles through 5G and other technologies. The FRSi4XX Series pump sources for Forward Raman amplifiers would extend transmission distances in ultrahigh-speed optical fiber communication more than conventional systems.

The maker says that the proliferation of smartphones has led to a dramatic increase in communication traffic, including the expansion of wireless backbones, cloud computing, video streaming, and the penetration of social networks. To deal with this traffic explosion, improvement in optical signal-to-noise ratio (OSNR) is becoming an important factor in soon-to-be-deployed ultrahigh-speed optical fiber communications such as 400 Gbps and beyond.

Existing erbium-doped fiber amplifiers (EDFA), which are widely used in current systems, do not have sufficient OSNR performance. Demand is increasing for Raman amplifiers due to their excellent noise characteristics. Forward Raman amplifiers, which make the most of the advantages of Raman amplification, are expected to be a technology necessary for increasing transmission distances.

The press release states that in the past, only the backward Raman amplifiers was used due to limitations of the noise characteristics of the pump source. Furukawa Electric’s FRSi4XX Series novel pump sources make it possible to realize forward Raman amplifiers and featuring high output as well as excellent low-noise characteristics.

The FRSi4XX Series pump source has high power output. The maker has achieved a high-output chip structure and high-efficiency coupling technology by leveraging the design, manufacturing technology and high-precision packaging technology of the InP (Indium Phosphide) optical semiconductor chips. The optical output of 100 mW or more was achieved through an optimized heat dissipation design.

The FRSi4XX pump series reduces noise by about 20 dB/Hz compared with conventional pump sources for Raman amplifiers. Combining the FRSi4XX Series with existing FOL1439 Series, yield pump sources especially well-suited to forward pumping Raman amplifiers.

The FRSi4XX Series pump sources have an optical output of more than 100 mW and Noise characteristic RIN of less than -130 dB/Hz over a temperature range of 25 to 70 degree Celsius at a wavelength ranging from 1420nm to 1500 nm.

For more details, contact the maker.

Raman Amplification
Raman amplification is a distributed process where signal amplification takes place inside the transmission fiber and Raman amplifiers are widely used fiber amplifiers in long-haul systems.

Raman scattering was first discovered by Sir Chandrasekhar Raman (an Indian Scientist) in 1928. Raman scattering describes a process in which the light photons are scattered from matter molecules to a higher wavelength (lower energy). The photon excites the matter molecules to a high (virtual) energy state, which then relaxes back to the ground state by emitting another photon as well as vibrational (i.e. acoustic) energy.

Due to the vibrational energy, the emitted photon has less energy than the incident photon, and therefore a higher wavelength. Stimulated Raman scattering describes a similar process whereby a higher wavelength photon stimulates the scattering process, i.e. the absorption of the initial photon, resulting in the emission of a second higher wavelength photon, thus providing amplification.

Unlike the Erbium-doped Fiber Amplifiers (EDFAs), where the gain spectrum is constant and determined by the Erbium atoms, the Raman amplification gain spectrum depends on the pump wavelength, with maximum gain occurring about 100nm higher than the pump wavelength.

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