Expanded bandwidth of FRL1441U Series – pump lasers for high output, low power consumption Raman amplifiers – for U-band application

Furukawa Electric Co., Ltd. (Head Office: 2-6-4 Otemachi, Chiyoda-ku, Tokyo; President: Hideya Moridaira) expanded the lineup of FRL144U Series, pump lasers for high output, low power consumption Raman amplifiers, to include newly developed pump laser for the U-band by expanding bandwidth from existing S-, C-, and L-bands, and will start mass production from April of this year. Furthermore, we optimized the design of laser chips mounted on existing FRL1441U Series, achieved fiber output of 1W at 35℃ in C-band, and developed pump lasers which allow for further lowering power consumption by reducing reactive power.

While communication traffic volume at data centers or 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 decreases 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, with the expansion into the U-band, the number of pump lasers used increases, so it is even more important for them to have high output power and low power consumption. In October 2022, Furukawa Electric achieved 800mW output in the C-band, and also expanded the lineup to include a 700mW pump laser for the S-band and low power consumption 500mW pump laser for the L-band. Product sample shipments of these pump lasers began in April 2023. With the FRL1441U Series, we have reduced the power consumption of the pump lasers used for existing Raman amplifiers in the S-, C-, and L-bands by 37% and made it possible to reduce the space used by using only 1 pump laser instead of the previous 2 unit through the development of the dual port pump laser.

This time, to support further expansion of bandwidth, based on the specification for the L-band, specifically 500ｍW output and maximum power consumption of 10W, we added a pump laser for Raman amplifiers for the U-band (wavelength range: 1520-1545nm), where achieving a higher output power was challenging, to the lineup of FRL1441U Series. Product sample shipment starts from January of this year, and mass production is scheduled to begin in April (See Table below).
Furthermore, while fiber output from the existing product for C-band is 800ｍW when the driving current is 4A at 35℃, this product achieved 1W as a result of optimizing the laser chip design (Fig. 1). Similarly to the existing products, this product was developed in the 14-pin butterfly package (Fig. 2), thereby reducing reactive power and contributing to further lowering power consumption. In order to offer more technical advantages to FRL1441U Series, we reduced electrical resistance of laser chip by more than 10% by optimizing the design of the chip, and developed the laser chip which enables high output power with low power consumption. On this background, it 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 chip structure. It also takes advantage of the optimized design of our patented high efficiency semiconductor laser chip structure.
An oral presentation of this product will be made at Photonics West 2024 to be held in San Francisco, USA, in January of this year (on Jan. 29, 2024).

Photonics West 2024

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 range optical node technology for realizing ultra-high speed, large volume networks” (Key Issue JPJ012368C04501).
Going forward, we will continue to develop high output, low power consumption laser chip technology 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