How High-Speed Optical Transceivers Work: From 10G to 1.6T with Hirundo's SFP+, QSFP28 and QSFP56 Series

Optical transceiver are the core photoelectric conversion devices in fiber-optic communication systems, often described as the "photoelectric interpreters" of the network world. They enable the high-speed, low-loss transmission of massive data across data centers, telecom networks, and AI computing clusters. Hirundo Optics offers a comprehensive portfolio of optical transceivers covering data rates from 10G to 800G/1.6T, including SFP+, SFP28, QSFP+, QSFP28, QSFP56, and active/direct attach cables (AOC/DAC). This article explains the operating mechanism of high-speed transceivers and introduces Hirundo's product series that meet the demands of modern intelligent optical networks.

Core Composition of an Optical Transceiver

A transceiver, about the size of a bank card, encloses a sophisticated miniature "photoelectric factory" composed of seven core units: Transmitter Optical Subassembly (TOSA), Receiver Optical Subassembly (ROSA), electrical signal processing chips (DSP, driver, TIA), precision passive optical components (lenses, isolators, WDM couplers), main control MCU, high-frequency PCB circuits, and miniature heat dissipation structures. The entire system revolves around bidirectional electro-optic and opto-electric conversion.

Optical Chip

The core components integrated inside TOSA and ROSA include lasers (DFB, VCSEL) and photodetectors (PIN, APD), responsible for signal conversion. Low-speed optical chips below 50 Gb/s have achieved full domestic production, while high-end products of 100 Gb/s and above still rely on imports. Hirundo leverages high-quality optical chips to ensure reliable transmission.

Electrical Chip

The "brain" of the transceiver includes laser driver chips, DSP chips, and TIAs. Driver chips amplify the electrical signal to drive the laser, TIAs amplify weak photocurrent from the receiver, and DSP chips perform encoding/decoding and compensate for signal impairments such as chromatic dispersion and polarization mode dispersion. For 4×25G products, driver chips and TIAs have realized domestic substitution; high-end DSP chips have long been supplied by international manufacturers.

Passive Optical Supporting Device

These include micro lenses, optical isolators, wavelength division multiplexers, and fiber coupling assemblies. They focus light beams, prevent reflected stray light, and enable multiplexing/demultiplexing of multiple wavelengths. They are equivalent to reflectors, condensers and flow dividers in optical paths, guaranteeing transmission efficiency.

Operating Mechanism: Transmit (TX) and Receive (RX) Chain

Transmit End (Electric-to-Optical Conversion)

The transmit chain can be visualized as a cargo packing process:

1. Massive electrical signals from servers/switches are fed to the DSP chip for encoding and signal pre-emphasis compensation to offset loss from PCB transmission.
2. The processed signals are delivered to the laser driver chip for waveform amplification.
3. Precise current from the driver drives the laser inside TOSA to emit light, modulating electrical signals into optical signals with varying brightness and wavelengths.
4. Micro lens assemblies converge the light beam, and optical isolators block reflected stray light to avoid interference.
5. The modulated optical signal is coupled into an optical fiber for ultra-low-loss transmission.

Receive End (Optical-to-Electric Conversion)

Attenuated optical signals arriving at the receiver undergo reverse processing:

1. Faint optical signals enter ROSA; lenses converge them onto the photodetector, which converts light into a weak photocurrent.
2. The transimpedance amplifier (TIA) amplifies the weak current and filters noise.
3. The distortion-corrected signal enters the DSP, which recovers the complete data through clock recovery, chromatic dispersion compensation, and error correction.
4. The DSP outputs standard digital electrical signals to the server or switch.
5. The MCU continuously monitors parameters such as temperature, voltage, and optical power, providing early warnings under abnormal conditions.

The core value of transceivers lies in overcoming the rapid attenuation that limits electrical signal transmission distance. Optical signals offer ultra-low loss, ultra-high speed, and far greater bandwidth than copper cables. Thanks to transceivers, massive data required by AI data centers can be rapidly exchanged between servers. Current mainstream rates cover 10 Gbps to 800 Gbps, with a roadmap to 1.6 Tbps.

Hirundo's Transceiver Product Series

Hirundo provides a wide range of optical transceivers and cables for different applications:

Why Choose Hirundo?

Hirundo is committed to delivering high-performance, reliable optical transceiver solutions that meet the ever-growing demands of intelligent networks. Our products undergo rigorous testing to ensure compliance with international standards such as IEEE 802.3 and ITU-T recommendations. Whether you need a standard 10G SFP+ for legacy infrastructure or a 200G QSFP56 for next-generation AI data centers, Hirundo offers a complete range backed by superior quality and customization capabilities.