Introduction to SOA Amplifier

SOA (Semi-conductor Optical Amplifier) semiconductor optical amplifier is a PN junction device using a strained quantum well structure. The external forward bias voltage forms a population inversion, and the external light enters and causes stimulated radiation to form optical signal amplification.

Advantages:

support high speed, high bandwidth, low power consumption, high gain, miniaturization, easy integration

Disadvantages:

cross-gain modulation and nonlinear interaction between different wavelength channels, polarization sensitivity, gain saturation

Compared with EDFA (erbium-doped fiber amplifier), some indicators of commercial devices are weaker than EDFA, but SOA amplifier still has characteristics that EDFA cannot replace, such as it can support O-band (1260~1360), E-band (1360~1460), L-band (1460~1530) amplification, and has the characteristics of low cost, small size and easy integration.

In the era of new infrastructure, SOA amplifier will be widely used in the access network and the edge of the metropolitan area network, as well as in the field of optical fiber sensing. .

SOA amplifier market application /SOA in optical fiber

With the improvement of SOA’s output optical power, small signal gain, gain polarization sensitivity, and noise index, SOA will play an increasingly important role in all-optical network communication and sensor networks. In addition to satisfying the amplification of 1310nm band, SOA can completely replace EDFA in some single-stage amplification fields of 1550nm band.

1,Carrier Optical Transport Network

With the construction of 5G network, the demand for bandwidth has increased sharply. At the edge of access network and metropolitan area network, 100G (4*25G CWDM4/LWDM4) high-speed transmission is required. 5~40km. At this time, the optimal cost solution is the 100G (4*25G) LWDM4+SOA solution, which uses 4*25G LWDM wavelength multiplexing to 100G, and then cooperates with SOA to increase the link margin.

In the fronthaul scenario of 5G base stations, in some scenarios where the base station is far away, the optical module type SOA can be used to increase the optical power margin, and realize the weak light transformation of the 25G signal rate of the 1310nm band and 1550nm band of the base station. Similarly, as home broadband is gradually upgraded to the WDMPON solution, SOA can facilitate the widespread deployment of WDM PON and improve the coverage and transmission distance of the WDM PON network.

In the application of the carrier network, the SOA can be integrated into the ROSA or TOSA of the optical module, or an independent SOA device or SOA optical module can be used for amplification.

2. Spectral amplification of network monitoring

This is the traditional application of semiconductor optical amplifier SOA. At present, with the rapid development of data services, the demand for data distribution monitoring in China is gradually increasing. It is usually carried out at the core network nodes for optical splitting monitoring. The split signal is usually very weak, and optical Amplifiers, and many 100G services are 1310 wavelengths, which can only be amplified by SOA. This scenario is currently the most widely used and mature application of SOA amplification.

3. Data Center Interconnect DCI

With the development of big data, the demand for high-bandwidth interconnection between data centers is gradually increasing. For high-speed services, because SOA can be used for optical signal relay amplification, the optical power margin of the link is improved and the transmission distance is extended. SOA can be applied to both 1310 band and 1550 band for high-speed service optical signal amplification.

This market usually uses independent SOA semiconductor optical amplification rack-mounted equipment. Recently, Jianhebafang has launched uSOA in the form of CFP2, and is currently developing SOA in the form of QSFP28 and SFP.

4. Application in distributed optical fiber sensing and laser radar system

SOA has excellent frequency response characteristics and high extinction ratio, and can be used as an optical switch or modulator. With the continuous improvement of SOA technology, it can replace the acousto-optic modulator AOM in most scenarios of fiber optic sensing to obtain narrow pulse laser with high extinction ratio.

In recent years, with the rapid development of intelligent traffic automatic driving and vehicle-road coordination, lidar has been widely used in both vehicle-mounted and roadside military. Due to the miniaturization and high gain of SOA, it can be applied to laser radar to obtain narrow linewidth laser and increase optical power, especially the optical chip laser radar of the next generation of local FMCW technology, which is a wider application of SOA in the future. field.

HYD TECHNOLOGY is a high-tech enterprise dedicated to the R&D and production of photonic integration technology

At present, a full range of SOA products have been launched, including 1310nm and 1550nm SOA chips, SOA COC, SOA butterfly devices, SOA optical modules, SOA optical amplification equipment, etc. At present, the whole process of SOA chip is domestically designed and produced, which is independent and controllable. Its performance has reached the international advanced level. It has passed the verification and trial of many domestic mainstream manufacturers, and it has been supplied in batches.

The amplification principle of SOA amplifier is the same as that of semiconductor lasers, and it also uses the phenomenon of particle number inversion caused by the excited transition between energy levels to perform optical amplification.

SOA in optical communication ,there are two types of SOA amplifiers:

One is to use the usual semiconductor laser as an optical amplifier, called F-P semiconductor laser amplifier (FPA);

The other is to coat the two end faces of the F-P laser with an anti-reflection film to eliminate the reflection at both ends to obtain broadband, high output, and low noise.

As early as the appearance of semiconductor lasers, the research on SOA amplifier began, but due to the high polarization sensitivity of the early semiconductor laser amplifiers, SOA amplifier was once silent.

However, in recent years, the successful development of strained quantum well materials has overcome the shortcoming of polarization sensitivity, and the performance has also been improved a lot.

The gain of the semiconductor optical amplifier can reach more than 30dB, and it can be used in both the 1310nm window and the 1550nm window.

If the gain can be kept flat in the corresponding use wavelength range, it can not only be used as a beneficial option for optical amplification, but also contribute to the realization of the 1310nm window WDM system.

  The SOA Amplifer working band can cover 1.3~1.6/um band, which cannot be realized by EDFA or PDFA.

But the biggest weakness is that the coupling loss with the optical fiber is too large, the noise and crosstalk are large, and it is easily affected by the ambient temperature, so the stability is poor.

In addition to being used for optical amplification, SOA can also be used as an optical switch and a wavelength converter .

● Gain response is fast;
● Adjustable light output, low noise figure;
● Simple structure, low power consumption, long life and low cost;
●Compatible with 100G/40G/10G rate service signal amplification;
●Single board can support up to 6 channels of 100G/40G/10G rate business signal amplification;
● It can simultaneously amplify optical signals in the 1270nm-1330nm band, covering the 1300 nm window, with a bandwidth greater than 60 nm;