Juniper QSFP-40G-LX4 Optical Module Sample Test Report

Juniper’s QSFP‑40G‑LX4 optical transceiver supports 40G Ethernet transmission up to 2 km over OS1 single‑mode fiber (SMF), 100 m over OM3 multimode fiber (MMF), and 150 m over OM4 MMF. Moduletek Laboratory tested a sample unit to verify its performance specifications and real‑world switch compatibility.

1. Product Overview

The Juniper QSFP‑40G‑LX4 is a 40G Ethernet optical transceiver with a commercial operating temperature range of 0°C to 70°C. Official key specifications and physical appearance are listed below.

Table 1 Official Specifications of Juniper QSFP‑40G‑LX4

Part Number	740-056705
Speed	40 Gigabit Ethernet
Product Type	Optical Transceiver
Connector	Duplex LC
Transmitter wavelengths (range)	Lane 0-1271 nm Lane 1-1291 nm Lane 2-1311 nm Lane 3-1331 nm
Receive lane wavelengths (range	Lane 0-1271 nm Lane 1-1291 nm Lane 2-1311 nm Lane 3-1331 nm
Transmitter output power,each lane (minimum)	-7.0 dBm(per lane)
Transmitter output power,each lane(maximum)	SMF 2.3 dBm MMF 4.3 dBm
Receiver input power,each lane (minimum)	-11.5 dBm(per lane)
Receiver input power,each lane (maximum	SMF 2.3 dBm MMF 4.3 dBm
Cable type	SMF MMF MMF
Core size/cladding	9/125 μm 50/125 μm 50/125 μm
Fiber grade	OS1 OM3 OM4
Effective modal bandwidth	—— 2000 MHz x km 4700 MHz x km
Distance	2 km 100 m 150 m
Maximum Power consumption (W)	3.5 W
Operating Temperature (range)	0°C to 70°C

JUNIPER QSFP-40G-LX4 Optical Module Physical Picture

Figure 1 Physical View of Juniper QSFP‑40G‑LX4

2. Switch Identification & Compatibility Test

The module was installed into a Juniper QFX5200‑32C switch. It established a normal LINK, and the port indicator illuminated properly.

The switch correctly read module information including type, part number and serial number. DOM parameters were within normal thresholds with no alarms.

Table 2 On‑Switch Identification Results

Item	Information Read by Switch
LINK
Identification
DOM Data

3. Key Performance Testing

All tests were performed with the module case stabilized at 45°C on a dedicated test fixture.

Table 3 Measured Performance Parameters

Fiber Type	Over OS1 Single-mode Fiber				OM3 Multimode Fiber
Parameter	Transmit Optical Power/dBm	Receiving Sensitivity (without fiber)/dBm	Receiving Sensitivity (with 2KM SMF/dBm	Power Consumption/W	Transmit Optical Power/dBm	Receive Sensitivity (without fiber)/dBm	Receiving Sensitivity (over 100M MMF)/dBm	Power Consumption/W
Channel 1	-0.41	-16.86	-16.49	2.148	1.18	-17.05	-15.03	2.214
Channel 2	-0.43	-15.97	-15.18		1.05	-15.32	-12.68
Channel 3	0.02	-16.81	-16.12		1.55	-15.81	-15.56
Channel 4	-0.46	-16.19	-15.66		0.99	-16.05	-14.79
Remarks		0 BER	0 BER			0 BER	0 BER

Eye diagram tests were also conducted at 45°C module case temperature.

Table 4 Eye Diagram Status

	Eye Diagram over OS1 SMF	Eye Diagram over OM3 MMF
Channel 1
Channel 2
Channel 3
Channel 4

Table 5 Eye Diagram Measured Parameters

Fiber Type	Over OS1 SMF						Over OM3 MMF
Parameter	Extinction Ratio (dB)	P-P Jitter (ps)	Rise Time (ps)	Fall Time (ps)	Margin Value (%)	Temperature (℃)	Extinction Ratio (dB)	P-P Jitter (ps)	Rise Time (ps)	Fall Time (ps)	Margin Value (%)	Temperature (℃)
Channel 1	4.29	29.34	37.3	48.5	21	45	4.33	28.98	36.9	47.2	24	45
Channel 2	4.45	28.8	42.5	45.4	23		4.41	28.44	42.3	44.1	25
Channel 3	4.35	25.2	25.6	48.2	24		4.37	29.51	38	48.4	20
Channel 4	4.12	26.86	41.2	44	25		4.12	28.44	41.2	44.4	25

Test results show that all key performance indicators of the sample module meet the official specifications published by Juniper.

Moduletek provides professional optical module testing and supporting services.

For further inquiries about the above content, please contact us at: sales@moduletek.com

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Juniper QSFP-40G-LX4 Optical Module Sample Test Report