PM Fiber Switch (Polarization Maintaining Optical Switch) is a passive component that selectively transmits, redirects or blocks optical signals from a given input port to a given output port in an optical fiber transmission line. At the same time, by using Panda PM fibers it’s able to maintain a well-defined state of polarization (SOP) of the light. Lfiber’s mechanical PM fiber switch features less than 0.8 dB insertion loss, high extinction ratio, very low crosstalk, and fast switching time. These PM fiber switches have been widely used in a variety of fiber-optic applications, including protection, restoration, testing & measurement, and monitoring in telecom applications and many PM fiber-optic systems. 
This page is to introduce LFIBER’s PM fiber switch controlled by RS-232 communication protocol. For the TTL control version, click Polarization Maintaining Optical Fiber Switch (TTL).
Demand for Polarization Maintaining (PM) Fiber Switch
For PM-applications, polarization-maintaining fiber (PMF) is the optimal technical choice for high performance. Demand for multi-channel PM fiber switch is increasing because they allow smooth re-direction of optical fiber routing in response to changes in data traffic or network problems. In this way, they increase the efficiency of data transmission over optical broadband networks and test equipment.
PM Fiber Switch (Polarization Maintaining Fiber Optical Switch) 
The polarization maintaining optical fiber switch (PM fiber switch) is an important device for PM fiber-optic applications in optical communications, networks and system. 
The PM fiber switch optically switches fiber circuits without doing expensive optical-electronic-optical (OEO) conversions. These can reduce the cost of optic-optic network and increase fiber transmission capacity and, at the same time, distribute optical signals to different subscribers. The PM fiber switch only rearranges the physical fiber circuit so that such a switch is transparent to all protocols, data formats, and modulation formats.


Polarization Maintaining (PM) Fiber Switch

PM Fiber Switch


  • Low Insertion Loss and High Reliability
  • Serial Interface (RS-232)
  • Modularized Design
  • Epoxy-free on Optical Path


  • Optical Signal Switching and Routing
  • Optical Network Monitoring
  • Testing of Fiber Optic Component
  • Military Communications

Specifications of the 1xN PM Optical Fiber Switch
Channel Number (N)1×N (N ≤ 16) or other channel counts on request
Fiber TypePanda PM fibers
Insertion Loss (dB)Typ: 0.5; Max: 0.8
Extinction Ratio (dB)≥ 20 dB (standard) or better
Operating Wavelength (nm)1310-1550
Testing Wavelength (nm)1310 or 1550
Return Loss (dB)≥ 50
Crosstalk (dB)≥ 70
Wavelength-Dependent Loss (dB)≤ 0.25
Temperature-Dependent Loss (dB)≤ 0.25
Repeatability (dB)≤ 0.02
Lifetime (cycles)≥ 10 million
Switching Time (ms)≤ 8 (adjacent channel)
Power Handling (mW)≤ 500
Power Supply5V / 500mA
Control ModeTTL
ConnectorFC, LC, SC, ST, etc.
Operating Temperature (℃)-20 to +70
Storage Temperature (℃)-40 to +85
Dimension (mm)135 × 64 × 32 mm, 19" rack or different sizes on request

  • For requests please see the ordering information section and specify the number of channels, operating wavelength range, control mode, etc.
  • The polarization maintaining (PM) fiber optical switch is powered by a universal AC/DC adaptor that is able to convert 100-250 VAC to 5 VDC.
  • Lfiber can offer a plug and play solution for directly programming (RS232 control) the switch via USB upon request. If there is a need, we can offer software solutions (based on Microsoft Windows OS) so that users can easily control the PM fiber optical switches.
  • Unless otherwise specified, the slow axis of the fiber is aligned with the key of the connector.
  • Standard port/channel counts of the PM fiber switches: 1×2, 1×4, 1×8, 1×16, 1×24, 1×32, 1×48, 1×64, 1×128, etc. Other channel counts are also available on request.
  • The PM fiber switches can be installed in 1U units on standard 19-inch racks. We offer customization upon request if needed.
  • Lfiber’s optical switches are customizable and the specifications are subject to change without notice.
  • For product customization or special requirements, please contact our sales representative.



RS232 Control via USB: Hardware Connection of the PM Optical Fiber Switch


Polarization Maintaining Optical Switches PM Optical Fiber Switch


RS232 Control via USB: Hardware Connection of the PM Fiber Optical Switches



Pin Configurations of the Polarization Maintaining (PM) Optical Fiber Switch

DB-9 Male Connector

Pin No.I / OSignalDescriptions
2InputRXDReceive Data
3OutTXDSend Data
9PowerVCC15.0 ± 5% VDC Power Supply (500mA)
1, 4, 6, 7NCNCVacancy


Dimensions of the Polarization Maintaining (PM) Optical Fiber Switch

Polarization Maintaining PM optical Switch PM Fiber Switch


Optical Route of the Polarization Maintaining (PM) Optical Fiber Switch

Polarization Maintaining PM Fiber Switch PM optical Switch


Control Chart of the Polarization Maintaining (PM) Optical Fiber Switch

PM Fiber Switch Polarization Maintaining PM optical Switch



Communication Protocol

  • “_” expression underline.
  • Communication protocols are all capital letters.
  • The communication protocol commands, “<” as the start, “>” as a terminator.

Optical PM Fiber Switch



Operating Instructions

COM Settings
Baud rate: 9600 | Data bits: 8 bit | Stop bit: 1 bit | Parity bit: None | Command error return “< OSW_ERROR >”

Software Control Chart (For Reference Only)

PM Fiber Switch Polarization Maintaining optical Switch


  • The PM optical switch transmits the command to control the optical switch through RS232 serial communication. The optical switch receives the command successfully and returns the response.

  • To program the PM fiber switch directly over USB (RS232 control), we can throw in a USB 2.0 to DB9 male serial cable (RS232 converter/adaptor), and then the switch can be connected to the USB port on your device. Click USB to DB9 Male Serial Cable Driver to download the driver for the converter/adaptor. 

  • The PM fiber switch is bidirectional in operation.


Ordering Information for the Polarization Maintaining (PM) Optical Fiber Switch
Port/Channel NumberTest WavelengthFiber TypeControl ModeFiber LengthConnector
1×N (N ≤ 16)1310 nmPanda PM fibersRS2320.50 mNone
Custom …1550 nmRS232 (via USB)1.00 mLC/UPC
Custom …1.50 mLC/APC
Custom …SC/UPC
Custom …

Related Products of PM Fiber Switch (Polarization Maintaining PM Optical Switch)