Low-crosstalk operation of directly modulated DFB laser array TOSA for 112-Gbit/s application

Area of Science:

• Photonics and Optical Communications
• Semiconductor Lasers
• High-Speed Data Transmission

Background:

• Advancements in high-speed optical communication systems necessitate improved transmitter performance.
• Electrical crosstalk in multi-channel laser arrays can degrade signal integrity and limit data rates.
• Directly modulated DFB lasers (DMLs) offer a cost-effective solution for high-speed optical transceivers.

Purpose of the Study:

• To fabricate and characterize a novel directly modulated DFB laser (DML) array transmitter optical sub-assembly (TOSA) for 112 Gbit/s operation.
• To suppress adjacent electrical crosstalk within the DML array TOSA.
• To demonstrate the feasibility of high-speed, error-free data transmission using the developed DML array TOSA.

Main Methods:

• Fabrication of a DML array chip integrated with a GND pad.
• Design of the DML array sub-assembly to mitigate electrical crosstalk.
• Characterization of TOSA 3-dB bandwidth and electrical crosstalk levels.
• Evaluation of OTU4 mask margins under simultaneous multi-channel operation.
• Demonstration of error-free transmission over 10-km single-mode fiber.

Main Results:

• The fabricated DML array TOSA achieved 3-dB bandwidths exceeding 18 GHz.
• Electrical crosstalk was suppressed to below -20 dB up to 18 GHz.
• OTU4 mask margins degraded by a maximum of only 6% under simultaneous 4-channel 28-Gbit/s (112 Gbit/s) operation.
• Error-free transmission was achieved across all lanes over 10-km single-mode fiber at 112 Gbit/s.

Conclusions:

• The developed DML array TOSA represents a significant advancement for 112 Gbit/s optical communication systems.
• Effective suppression of electrical crosstalk enables high-speed, reliable data transmission.
• The technology demonstrates potential for cost-effective, high-performance optical transceivers.