Narrow Linewidth Tunable Laser Source for Telecommunications & Optical Networks

Why Coherent Optical Networks Expose Laser Phase Noise

Telecommunications and optical networks are the application this laser was primarily designed for. Every link beyond 100 Gbit/s is coherent: data rides on the amplitude and phase of light and is recovered by mixing it with a local oscillator.

Each step up in format, from QPSK to 16QAM, 64QAM and beyond, packs more constellation points into the same space. The phase error a receiver can tolerate gets smaller every time.

Laser phase noise lands directly on that error. It blurs the constellation and raises the bit error ratio, until a format stops working no matter how good the modulator, fibre or DSP is.

A Narrow Linewidth Tunable Laser That Drops Out of the Error Budget

Below 1 kHz linewidth, this laser adds so little phase noise that it all but disappears from the measurement. That makes it a neutral carrier and local oscillator: when you compare carrier-phase recovery, equalisation or probabilistic shaping schemes, the difference you see belongs to the algorithm, not the light source. It is just as useful for exposing the real linewidth penalty of a vendor laser or integrated tunable assembly.

What Sub-1 kHz Linewidth and Grid Accuracy Give a Telecom Lab

Telecom work needs two things from a source at once: a quiet phase for research, and an exact frequency for compliance.

• Fair DSP comparisons: with the laser out of the noise budget, algorithm results can be trusted.
• Grid compliance you can prove: a reference more accurate than the transceiver under test shows it sits on its ITU-T channel and stays clear of its neighbours.
• Clean benchmarking: a candidate laser’s true penalty only shows next to a quieter source.

From Algorithm Bench to Transceiver Test Line

The same lab often runs exploratory research by day and repeatable qualification runs overnight. The source has to serve both.

Every channel from one source

Coarse tuning reaches any channel in the specified range, so one laser covers a whole test plan without swapping hardware.

Fine steps for response mapping

Fine tuning sets a transceiver exactly on grid, and steps frequency in small increments to map filter shape, resonances, receiver tolerance or a DSP’s acquisition range.

1 port to 48 ports

The CoBrite DX takes one to four ports, the compact DX2 one or two, and the 19-inch MX up to forty-eight. Variants mix on one bench, so a lab grows its system instead of replacing it.

Polarisation held fixed

Dual-polarisation formats such as DP-QPSK are standard in coherent systems. Polarisation-maintaining output keeps one variable out of the receiver chain, and programmatic control keeps every sweep scripted and logged.

Closing the Coherent Test Loop

A coherent test bench needs a trusted transmitter, a trusted receiver and a way to check the spectrum. Here the laser sits in a CoBrite DX, DX2 or MX chassis and drives the OMFT IQ Reference Transmitter, which generates DP-QPSK and higher-order QAM signals to judge a receiver or transponder against. The CORX Coherent Optical IQ Receiver uses a matched narrow-linewidth local oscillator to measure a transmitter’s real modulation quality, and the ID OSA Optical Spectrum Analyser confirms centre wavelength, linewidth and side-mode suppression before every compliance run.

With both ends of the link trusted, an impairment can be pinned on the device under test rather than the bench, which saves the most time in coherent development.

Who Uses It

• Telecom equipment manufacturers
• Optical transport and transceiver developers
• Network operator laboratories
• Photonics research groups
• Academic and institutional coherent transmission programmes

Supply and Support in India

United Spectrum Instruments (USI), Chennai, is the authorised distributor for ID Photonics GmbH in India and supplies this laser with the CoBrite DX, DX2 and MX chassis, OMFT transmitter, CORX receiver and ID OSA.

Telecom labs usually grow in stages, from a four-port benchtop now to a high-density rack later. Buying through USI keeps port planning, wavelength bands and compatibility consistent, so earlier measurements stay valid as the system expands.

Request a Configuration

Download the brochure from this page, use the Enquire Now button, write to sales@unitedspectrum.in, or call +91 93631 83748 / +91 97899 04948. Please mention:

• Target modulation formats and line rates
• Role of the source: carrier, local oscillator or both
• ITU-T channels and wavelength band
• Ports needed now and later, and preferred chassis