ERM-202 – Extinction Ratio Meter


The ERM-202 is a single or dual channel polarization extinction ratio (PER) meter. When used with a broadband source, it directly measures PER. Single and dual channel models are available. The single channel instrument can be upgraded to a dual-channel version at a later date. By combining low noise circuitry with a high resolution stepper, the ERM series achieves a PER dynamic range of 50 dB.

These instruments are the first to market with OLED displays, a high contrast bright readout that allows the data to be observed from several feet away. The instruments can be operated from the front panel or via remote control. The operator can choose from 4 measurement speeds to optimize speed or accuracy and can observe multiple parameters on the front panel screen including PER, axis angle, power ratios, and optical power.

The measurement data can be stored and recalled for comparison purposes from the front panel as well. Full digital or remote control is included for unattended or system applications.


  • One or Two Measurement Channels
  • Free Space Input
  • Front Panel or Remote Control
  • 50 dB PER range
  • Bright OLED display
  • Store and Recall Functions


  • Verification of PM connectorization and splices
  • Testing PM fiber coils
  • Simultaneous measurement of PER and power ratio
  • Testing Y-branch fiber gyro IOCs
  • Testing PM couplers (PMC), or polarization beam splitters (PBS)
  • Evaluating the performance of depolarizers

Operating Wavelength Range1: 1260 to 1620 nm or 960 to 1160 nm
Calibrated Wavelengths2: 1550 and 1310 nm (1260-1620nm version),  980 and 1064 nm (960-1160nm version)
PER Dynamic Range: > 50 dB (1260-1620nm version), > 40 dB (960-1160nm version)
PER Ranges3: 0 to 50 dB (for input power of -5 to 10 dBm, 1260-1620nm version), 0 to 40 dB (for input power of 0 to 10 dBm, 960-1160nm version)
                         0 to 30 dB (for input power >-25 to -5 dBm, 1260-1620nm version), 0 to 30 dB (for input power >-20 to 0 dBm, 960-1160nm version)
PER Resolution: 0.1 dB
PER Accuracy: ±0.15 dB for ER < 30 dB
Angular Resolution: 0.06°
Angular Accuracy: ±1°
Power Measurement Accuracy: ±0.5 dB
Power Resolution: 0.02 dBm (PER < 30)
                                    0.2 dBm (PER > 30)
Input Optical Power Range: -30 dBm to 10 dBm (1260-1620nm version), -20 dBm to 10 dBm (960-1160nm version)
Measurement Speeds: 0.1, 0.2, 0.4, 1 seconds
                                  (Single channel version also has 10s speed option
                                  and manual polarizer control mode)
Connector Type1: Free space adapter for FC connector
Optical Power Damage Threshold: 300 mW
Operating Temperature: 0 °C to 40 °C
Storage Temperature: -20 °C to 60 °C
Display: OLED graphic display
Communication Interfaces: USB, RS-232, Ethernet, and GPIB
Analog Output4: 0 – 5V (BNC for each channel)
Power Supply: 100 – 240 VAC, 50 – 60 Hz
Dimensions: 2U 19” half rack width 14” (L) x 8.5 “ (W) x 3.5” (H)
Notes: Specifications given at 23±5°C.
Other wavelength ranges and connector types may be available.
Other calibrated wavelengths may be available.
For measurement at or slower than 0.4s/cycle.
Analog output voltage scales with log of measured power after the polarizer.