What equipment is required for the production and testing of 800G optical modules?

What equipment is required for the production and testing of 800G optical modules?

The testing of 800G optical modules includes reception performance testing and transmission performance testing. The core equipment list and logic are as follows:
1、 Testing equipment
1.1MCB carrier board
Configure two MCB carrier boards to place the DUT module and the standard module respectively. The optical module is inserted into the carrier board and connected to the error code meter through a high-speed RF cable. Two carrier boards can ensure the independence of RX testing and TX testing. If using loopback testing, only one carrier board is needed. The 800G optical module requires an 8T8R optical path, which corresponds to the requirement of 16 pairs of differential signals for the Gold Finger, which means 32 RF cables/carrier boards.
1.2 Temperature Control Equipment
MCB carrier boards are usually equipped with temperature and detection devices to support testing performance at different temperatures. Temperature control equipment is generally loaded on the MCB carrier board of the DUT. Integrating temperature control onto the MCB carrier board can simplify equipment.
1.3 Error code analyzer
Configure two 800G bit error testers to emit PRBS sequences and drive RX and TX tests respectively. If the standard optical module supports PRBS sequence, it can save one bit error detector and use the upper computer to command the standard optical module to send the test sequence. Drive RX test (bit error test): Generate a test sequence, receive the return sequence, and compare the error between the transmitter and receiver, that is, the bit error. Drive TX test (eye diagram test): Generate a test sequence for the DUT, and the DUT emits light according to this sequence. The internal integration of MCB carrier board and temperature control equipment in the error code analyzer can further simplify the equipment.
1.4CDR Clock Equipment
The optical signal is sent periodically, and CDR identifies the edge of this timing period from the optical signal.
1.5 Oscilloscope
According to the timing signal given by CDR, the optical signal data is superimposed periodically to form an eye diagram. If the oscilloscope supports 4 inputs and 800G testing, then two units are required. More expensive, if you want to save money, you can use a light switch to switch.
1.6 Optical switch
Switch the optical path between eye diagram testing and power testing.
1.7 Optical power meter
Measure output optical power, 8 channels. The optical power meter can be integrated into the optical switch, simplifying the equipment.
1.8 DC power supply
Provide stable DC power to the MCB carrier board.

2、 Test system construction logic
2.1. RX reception performance test (bit error rate, sensitivity)
Signal flow: Error code analyzer 2 → Standard optical module → Optical attenuator → DUT → Error code analyzer 1
Key equipment: optical attenuator (used for scanning power points), standard optical module (used as a light source).
Purpose: To measure the bit error rate of DUT at different optical powers by changing the attenuation amount.
2.2. TX emission performance test (eye diagram, optical power)
Signal flow: Error code analyzer 1 → DUT → Optical switch → (power meter/oscilloscope+CDR)
Key equipment: Optical switch (route switching), CDR (clock recovery, for PAM4 signals).
Purpose: To verify the emitted light power and signal quality (the eye diagram should display the three “eyes” of PAM4).
3、 Key points of special configuration for 800G testing
Channel quantity: 800G adopts 8 channels (8T8R), and MCB carrier board metal fingers need to correspond to 16 pairs of differential signals (32 RF cables).
Signal type: For PAM4 modulation, the oscilloscope must be paired with CDR equipment to accurately capture the eye diagram.
Simplified solution: The error detector can integrate MCB and temperature control functions. The optical switch can be integrated with an optical power meter. If loop back testing (DUT self collecting) is used, it can reduce one MCB carrier board and standard module, but the testing items may be limited.

4、 Explanation of key terms
PRBS: Pseudo random sequence, simulating real data traffic.
MCB: Module compliance carrier board, testing fixture.
CDR: Clock data recovery, extracting clock from optical signals.
PAM4 eye diagram: four level pulse amplitude modulation, eye diagram presents four steps (three eye openings)