Hello, the answers to your questions are as follows: 1. VOA (# 13554) is a kind of attenuator, which can be used in a WDM scheme. According to the specific situation, if necessary, you need to add the attenuator. 2. You can choose 2 pcs # 13554 products as a dual-channel to use, if you must need duplex channel VOA, this requires further confirmation with our factory; 3. VOA (# 13554) can be used for single-mode(1310nm), it’s okay; 4. You mean you want an OTN scheme? If so, you need to confirm the following relevant information: (1) What is the distance between every span? And how about the link loss@1310nm and @1550nm? Fiber type, G652, G655, or others? Dual fiber or single fiber? (2) What's the data rate between each span? 1G or 10G or other? And how many businesses do you plan to transmit? (3) Is there any plan to expand and upgrade in the future? (4) Is there network protection, monitoring, or other custom needs, such as business, line and equipment protection, line, board, spectrum, and traffic monitoring, etc.? By H***e on 06/18/2020

Thanks for your question. This attenuator is a mechanically adjustable attenuator that has no attenuation of brightness, so this fiber optic attenuator does not require calibration. By *** on 06/10/2019