Polarization Maintaining Multiplexer
A polarisation maintaining multiplexer combines many laser wavelengths into one fibre while keeping every channel in the same, stable polarisation state. That matters whenever the...
Polarization Maintaining Multiplexer
Polarisation-Maintaining DWDM Multiplexer for Coherent Channel-Comb Generation — PMUX by ID Photonics
A polarisation maintaining multiplexer combines many laser wavelengths into one fibre while keeping every channel in the same, stable polarisation state. That matters whenever the combined light must pass through polarisation-sensitive devices such as Mach-Zehnder or IQ modulators, which only work correctly on a single, aligned polarisation.
The PMUX from ID Photonics GmbH, Germany, is a 19″ rack-mounted PM multiplexer built to complement the CoBrite MX multi-channel tunable laser. Its arrayed waveguide grating (AWG) version combines high channel counts on a fixed 50 GHz or 100 GHz grid with about 6 dB insertion loss and a polarisation extinction ratio of 20 dB typical. For low channel counts or flexible-grid plans, PM couplers can be built in instead, or combined with the AWG in a hybrid design. The PMUX runs autonomously once powered, with status available over USB.
United Spectrum Instruments is the official authorised distributor of the PMUX in India, providing configuration guidance, quotations, delivery and after-sales technical support across the country.
The PMUX is a polarisation-maintaining DWDM multiplexer that turns a CoBrite MX laser array into an aligned channel comb for modulated DWDM spectrum emulation — available in India through United Spectrum Instruments.
Understanding the Polarisation Maintaining Multiplexer
What is a polarisation maintaining multiplexer?
A wavelength multiplexer collects light from many lasers, each at its own wavelength, and combines them onto one output fibre. A standard multiplexer uses ordinary single-mode fibre, so the polarisation of each channel drifts randomly. A polarisation maintaining (PM) multiplexer uses PM PANDA fibre and PM components throughout, so every channel leaves the output aligned to the same polarisation axis.
Why polarisation alignment matters
Lithium niobate and indium phosphide Mach-Zehnder modulators are strongly polarisation dependent. If channels arrive at the modulator with mixed or drifting polarisations, some are modulated fully, others weakly or not at all, and the result changes over time. Keeping all channels aligned means one modulator can impose data on an entire comb of channels at once, stably and repeatably.
Emulating a loaded DWDM system
The classic PMUX setup combines the outputs of a CoBrite MX multi-channel tunable laser into one PM fibre, then passes the comb through a Mach-Zehnder or IQ modulator. The result is a set of real, modulated DWDM channels that behaves like live traffic. A 10 dB tap after the multiplexer lets an optical spectrum analyser monitor the comb. This is far less costly than a separate modulator per channel, while still reproducing realistic spectral and nonlinear behaviour.
AWG, coupler or hybrid
- AWG-based PMUX — for high channel counts on a fixed 50 GHz or 100 GHz grid, with a low, uniform insertion loss of about 6 dB.
- PM coupler-based PMUX — for low to medium channel counts or flexible-grid plans. Couplers accept any wavelength, avoiding the cost and configuration effort of tunable filters or wavelength-selective switches.
- Hybrid PMUX — AWG and couplers in one chassis, for example a fixed grid plus a few flexible “channel under test” positions.
Technical Specifications
Optical Performance — AWG-Based PMUX
| Parameter | Specification |
| Channel Spacing | 50 GHz or 100 GHz |
| Insertion Loss | 6.0 dB typical |
| Uniformity Across Band | 1 dB typical, 1.5 dB max |
| Polarisation Extinction Ratio | 16 dB min, 20 dB typical |
| Number of Channels | Customer specified |
| Channel Range | Customer specified |
| Channel Centre Offset | ±0.04 nm |
| 3 dB Passband | 0.55 nm (100 GHz version) |
| Input / Output Connectors | FC/APC, FC/PC or SC/PC |
| Optical Fibre | Polarisation-maintaining PANDA fibre |
Configuration Options
| AWG-Based | High channel counts, fixed 50/100 GHz grid, low insertion loss |
| PM Coupler-Based | Low to medium channel counts, flexible grid |
| Hybrid | AWG and PM couplers combined in one chassis |
Mechanical and Operating
| Form Factor | 19″ rack-mountable, rugged design |
| Dimensions (H × W × D) | 100 × 460 × 540 mm (4 × 19 × 21 in) |
| Operation | Autonomous after power-up; status via USB with Windows GUI |
| Power Supply | 100–240 VAC, <10 W, 47–63 Hz |
| Operating Temperature | 0 to 50 °C, non-condensing |
| Storage Temperature | −20 to 70 °C, non-condensing |
| Companion Laser | Designed for the CoBrite MX tunable laser chassis |
Channel count, channel plan and connector type are specified at order. Contact United Spectrum Instruments for a configuration datasheet.
Key Features and Advantages
Polarisation Preserved on Every Channel
PM PANDA fibre and PM components throughout keep every channel aligned, with a polarisation extinction ratio of 20 dB typical (16 dB minimum). One downstream modulator can then modulate the whole channel comb uniformly.
High Channel Counts on 50 or 100 GHz Grids
The AWG-based version combines large numbers of channels with about 6 dB insertion loss, 1 dB typical uniformity across the band and channel centres within ±0.04 nm of the ITU grid.
Flexible-Grid Option with PM Couplers
For flexible-grid or low-channel-count work, PM couplers accept any wavelength and need no configuration, avoiding the cost and complexity of tunable filters or wavelength-selective switches while still preserving polarisation.
Hybrid AWG and Coupler Designs
AWG and coupler paths can be combined in one chassis, for example a dense fixed-grid background plus flexible positions for channels under test.
Custom Channel Plans
The number of channels, the channel range and the connector type are specified to your test plan, so the PMUX matches your laser configuration and DWDM scenario exactly.
Seamless Match with CoBrite MX
The PMUX is designed as the companion to the CoBrite MX multi-channel tunable laser. MX lasers already output on PM fibre, so the full chain from laser to modulator stays polarisation maintained.
Plug In and Run
The PMUX operates autonomously as soon as it is powered, drawing less than 10 W. A USB connection and Windows GUI provide status information when needed.
Rugged 19″ Rack Design
The rack-mounted chassis integrates neatly alongside CoBrite MX mainframes and other test equipment, and operates from 0 to 50 °C.
Applications Across Industries
Modulated DWDM Spectrum Emulation
The core application: combine CoBrite MX lasers through the PMUX and modulate the entire comb with a single modulator, creating realistic loaded DWDM spectra for testing transceivers, line systems and amplifiers at a fraction of the cost of one transmitter per channel.
Optical Line System and Amplifier Testing
Telecom equipment makers use PMUX-based channel combs to load EDFAs, ROADMs and transmission links in telecommunications and optical networks, measuring gain flatness, tilt and nonlinear interaction under realistic traffic.
Coherent Channel-Under-Test Experiments
A modulated PMUX comb provides the neighbouring channels while an OMFT transmitter generates the channel under test, allowing crosstalk and nonlinear penalty measurements on next-generation coherent formats.
Defence and Secure Communication
In defence and secure communication programmes, the PMUX supports multi-wavelength optical link testbeds and polarisation-sensitive photonic subsystems.
Integrated Photonics and Quantum Research
Silicon photonic and quantum photonic circuits often accept only one polarisation. The PMUX delivers multiple wavelengths to such chips in a single, aligned PM fibre.
Multi-Wavelength Component Testing
In opto-electronic packaging and component production, a PM channel comb tests polarisation-sensitive modulators and PICs at several wavelengths simultaneously.
Why Choose United Spectrum Instruments?
Official Authorised Distributor in India
United Spectrum Instruments is the authorised Indian distributor for ID Photonics, so you receive a genuine PMUX backed by the manufacturer.
Help Specifying Your Channel Plan
The PMUX is built to order. We help you define channel count, grid spacing, AWG, coupler or hybrid architecture and connectors, and match it to your CoBrite MX configuration.
Experience with Indian Research and Industry
We work with IITs, CSIR laboratories, defence establishments, telecom companies and photonics start-ups across India and understand their procurement and documentation requirements.
Delivery and Local Technical Support
We deliver anywhere in India and provide after-sales support for installation, system integration and troubleshooting.
A Complete DWDM Test Chain
Alongside the PMUX, we supply CoBrite MX lasers, automatic bias controllers, PM EDFAs and optical spectrum analysers, so the full channel-comb setup can come from one partner.
Contact Us
Phone: +91 93631 83748 / +91 97899 04948
Email: sales@unitedspectrum.in
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FAQs
What is a polarisation maintaining multiplexer?
A polarisation maintaining (PM) multiplexer combines several laser wavelengths into one PM fibre while keeping every channel in the same polarisation state. This lets polarisation-sensitive devices such as Mach-Zehnder modulators act on all channels uniformly.
What is the ID Photonics PMUX?
The PMUX is a 19″ rack-mounted PM multiplexer from ID Photonics GmbH, designed to combine the outputs of a CoBrite MX multi-channel tunable laser into one aligned channel comb for DWDM spectrum emulation.
Why does polarisation matter when combining DWDM channels?
Mach-Zehnder and IQ modulators are strongly polarisation dependent. If channels arrive with random or drifting polarisation, modulation depth varies between channels and over time. A PM multiplexer keeps all channels aligned so one modulator works on the whole comb.
What channel spacing does the PMUX support?
The AWG-based PMUX is available for 50 GHz or 100 GHz ITU grid spacing. For flexible-grid plans, PM couplers can be used instead of, or together with, the AWG.
How many channels can the PMUX combine?
The number of channels and the channel range are specified by the customer. AWG-based designs suit high channel counts, while coupler-based designs suit low to medium counts.
What is the insertion loss of the PMUX?
The AWG-based PMUX has about 6.0 dB insertion loss, with 1 dB typical (1.5 dB maximum) uniformity across the band.
What polarisation extinction ratio does the PMUX achieve?
The polarisation extinction ratio is 20 dB typical, with a minimum of 16 dB, using PM PANDA fibre throughout.
What is the difference between AWG, coupler and hybrid PMUX versions?
AWG versions give high channel counts and low loss on a fixed grid. Coupler versions accept any wavelength for flexible-grid plans without configuration. Hybrid versions combine both in one chassis.
Does the PMUX need software to operate?
No. It runs autonomously as soon as it is powered. A USB connection and Windows GUI provide status information when required.
Which connectors are available on the PMUX?
Input and output connectors can be FC/APC, FC/PC or SC/PC, specified at order.
What are the size and power requirements of the PMUX?
The PMUX is a 19″ rack unit measuring 100 × 460 × 540 mm. It runs on 100–240 VAC, 47–63 Hz, draws less than 10 W and operates from 0 to 50 °C.
Who is the authorised distributor of the PMUX in India?
United Spectrum Instruments, Chennai, is the authorised distributor of ID Photonics products, including the PMUX, in India, supplying research institutions, defence establishments and telecom companies nationwide.
How can I get a quote or datasheet for the PMUX in India?
Use the Get in Touch form on this page, email sales@unitedspectrum.in, or call +91 93631 83748 or +91 97899 04948. Share your channel count, grid spacing and laser setup, and we will propose a configuration and quotation.
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