Experience unparalleled connectivity with 3Coptics, your go-to destination for professional optical solutions. Our commitment to excellence extends to providing cutting-edge fiber optics, backed by reliable services and support for your optical network needs. Unlock the full potential of your network with seamless connectivity solutions and dedicated customer support. Choose 3Coptics for advanced optical technology that optimizes and elevates your network performance.wga vape https://wgavape.com

DML Vs. EML Laser Techonology

2023-08-24 14:51:57

While discussing optical transceivers (especially 100G), we’re often asked about the two different types of laser technology: DML and EML. What is the difference between these two technologies? How important is this distinction on a day-to-day level? This article will answer all of these questions.

Directly Modulated Laser (DML)

DML refers to a directly modulated laser diode. This laser can also be called a distributed feedback (DFB) due to the structure used to build it. A DML features a single chip with a simple electrical circuit, making it ideal for circuit designs that require a small footprint and low power consumption. It places information on the optical beam by modulating an on/off electrical input generated by a driver IC. This is in turn directly applied to the laser dioide, which generates the modulated optical signal output.

Benefits of DML

DMLs tend to be much more stable than lasers like FP abd DBR as the grating and the reflection are not only at the two ends of the cavity of the laser but are almost continuous along the cavity.
DMLs feature a single chip and provide a simple circuit design, making them more compact and fit into more small-sized configurations.
DMLs generally cost relatively less and have low power consumption since optical signals are modulated by current change in a DML.
Compared to Fabry-Perot lasers, DMLs have a narrower spectral line width, meaning higher modulation speed and longer transmission distance.

Limits of DML

There is high chromatic dispersion in DMLs because direct modulation changes the laser properties directly.
DMLs have relatively low frequency response and extinction ratio as they are all limited by the relaxation frequency.
Associated frequency shifts, coupled with dispersion in the fiber, cause the performance of a DML to degrade over longer reaches (>10km).

Electro-absorption Modulated Laser (EML)

EML refers to an electro-absorption modulated laser. This design integrates a laser diode (structurally similar to a DML diode) with an electro-absorption modulator (EAM) in a single chip. The laser diode operates under a continuous wave (CW) condition, and input on/off signals are applied to the EAM section to generate optical output. This design features lower chromatic dispersion, so it’s better suited to higher data rate transmission over longer distances.

Benefits of EML

EMLs feature low chromatic dispersion since the process of modulation will not change laser properties constantly.
EMLs can operate at higher modulation speeds and have much lower chirp compared to DML.
EMLs are an ideal choice for high speed and long distance transmission because of lower dispersion in the fiber.

Limits of EML

EMLs are more power-consuming as there is an electro-absorption modulator (EAM) integrated within the chip.
EMLs require a more complex electrical configuration and diode layout.
EMLs generally cost more as they use electric absorption to modulate signals.