The range of a QSFP-DD (Quad Small Form-Factor Pluggable Double Density) transceiver can vary depending on the specific type of optics used. QSFP-DD is a high-density transceiver form factor designed for high-speed data transmission in data centers and telecommunications networks. Here are some common types of QSFP-DD optics and their associated ranges:

1. QSFP-DD SR8 (Short Range 8):

• QSFP-DD SR8 modules use multimode fiber (MMF).

• Typically supports distances up to 100 meters.

2. QSFP-DD DR4 (Data Center Reach 4):

• QSFP-DD DR4 modules use single-mode fiber (SMF).

• Typically supports distances up to 500 meters.

3. QSFP-DD FR4 (Four-Wavelength WDM Reach 4):

• QSFP-DD FR4 modules use single-mode fiber.

• Typically supports distances up to 2 kilometers.

4. QSFP-DD LR4 (Long Range 4):

• QSFP-DD LR4 modules use single-mode fiber.

• Typically supports distances up to 10 kilometers.

5. QSFP-DD CWDM4 (Coarse Wavelength Division Multiplexing 4):

• QSFP-DD CWDM4 modules use single-mode fiber.

• Typically supports distances up to 2 kilometers.

6. QSFP-DD PSM8 (Parallel Single Mode 8):

• QSFP-DD PSM8 modules use single-mode fiber.

• Typically supports distances up to 2 kilometers.

It's important to note that the distances mentioned above are general guidelines, and the actual reach can depend on factors such as the quality of the optical components, the type and quality of the fiber used, and environmental conditions. Additionally, advancements in technology may lead to modules with improved performance and longer reach.

When considering the deployment of QSFP-DD optics, it's recommended to refer to the specific datasheet or documentation for the QSFP-DD module in question to obtain accurate distance specifications for the intended application.