FRL1441U Series – pump lasers for Raman amplifiers achieved ultra-low power consumption at 500mW output

Furukawa Electric Co., Ltd. (Head office: 2-6-4 Otemachi, Chiyoda-ku, Tokyo; President: Hideya Moridaira) successfully operated the FRL1441U Series pump lasers for high output, low power consumption Raman amplifier in the C-band at 55℃, and by reducing reactive power by more than 50%, the newly developed LD chip consumed 3.7W at 500mW fiber output, which is less than half the 8W power consumption of existing LD chips. In addition, we have started development of mass production technology.

While communication traffic volume at data centers and elsewhere has been increasing on the background of the popularization of cloud service and the emergence of generative AI, along with increasing data transmission speed, the transmission distance decreased due to degradation of the OSNR^{(note 1)} on the signal receiving side. In particular, when existing communication systems are used at faster transmission speeds, the role of the Raman amplifier, which can amplify optical output power without attenuation of the signal light quality, will become more important. Also, because the bandwidth of the signal expands as a result of high-speed transmission, it is necessary to extend the bandwidth in order to enable high volume transmission. Thus, Raman amplifiers need to have high flexibility to amplify the light source at a discretionary range based on the selection of the pump laser wavelength. On the other hand, in addition to the traditional C- and L-bands, with the expansion into the S- and U-bands, the number of pump lasers used increases, so it is even more important for them to have high output power and low power consumption.
For pump lasers, reducing the power consumption of the thermoelectric cooler element leads to reducing overall pump laser power consumption (Fig. 1). When pump lasers are used in hot environments, it is necessary to cool the LD chip, but this increases the power consumption of the thermoelectric cooler element, causing overall pump laser power consumption to rise. Therefore, enabling the LD chip to operate at high temperatures is important for reducing pump laser power consumption.

The FRL1441U Series reduces the power consumption of the pump lasers used for existing Raman amplifiers in the S-, C- and L-bands by 37%. In addition, development of a dual port pump laser makes it possible to reduce the space used by using 1 pump laser instead of the previous 2 units. This time, we achieved 840mW output in the C-band at an LD chip operating temperature of 55℃ by 14 pin butterfly package platform (Fig. 2, 3). This achievement was made by optimizing the LD chip to realize with higher laser output and reduced electrical resistance of the laser element. Also, through large reduction to reactive power by operating the laser element at 55℃, we confirmed that power consumption of the widely used 500mW fiber output LD chip is reduced to 3.7W, which is less than half of the 8W power consumption of existing products. We have started development of mass production technology. This development uses our optical semiconductor processing technology using InP^{(note 2)} semiconductor materials developed over more than 25 years and high accuracy fiber coupling technology, as well as the application of our unique low loss, high efficiency semiconductor laser device structure. It also takes advantage of the optimized design of our patented high efficiency semiconductor laser device structure.^{(note 3)}
An oral presentation of this product will be made on July 2 at OECC 2024 to be held in Melbourne, Australia in July of this year.

OECC 2024

Paper #349

The current development was conducted and achieved as part of the National Institute of Information and Communications Technology (NICT) commissioned research “Beyond 5G – Development of extended rate optical node technology for realizing ultra-high speed, large volume networks” (Key Issue JPJ012368C04501) and the 2024 Function Realization and International Joint R&D Program “Innovative ICT Fund Projects for Beyond 5G/6G” (JPJ012368G60101).
Going forward, we will continue to develop high output, low power consumption laser chips, and contribute to accelerated reductions in module power consumption and the establishment of environmentally-friendly networks.

Achieved 800mW output with a pump laser for C-band Raman amplifiers

Development of a new pump laser for high output power, low power consumption Raman amplifiers by expanding the range of the FRL1441U Series to support the S-band and L-band

Development of a high output, low power consumption, small S-,C-,L-band dual port pump laser for Raman amplifiers