NetTest TUNICS series tunable external cavity laser

TUNICS Tunable Laser Technology Analysis: The Core Engine for High Performance Fiber Testing

In modern fiber optic communication systems, especially with the widespread application of Dense Wavelength Division Multiplexing (DWDM) technology, the performance requirements for light sources are becoming increasingly stringent. As the core equipment for optical communication testing and system verification, the stability, accuracy, noise control, and tuning range of tunable lasers directly determine the reliability of the testing system. The TUNICS series of tunable external cavity lasers, with its multiple patented designs and outstanding performance indicators, has become a technological benchmark in this field.

This article will comprehensively analyze the technical advantages and engineering value of TUNICS series lasers from five dimensions: optical design, core functions, product series, modular platform, and application scenarios.

Core Technology Architecture: Stability, Self Alignment, and No Jumping Mode

1. Ultra stable self aligning laser cavity

Traditional tunable lasers, due to mechanical drift, temperature changes, and other factors during long-term operation, can experience a significant decrease in output power and spectral purity caused by small displacements of optical components. The TUNICS series adopts a patented external cavity design, with the core being its dihedral corner retroreflector, which is composed of a 180 ° folding prism, equivalent to a "one-dimensional pyramid prism". This structure ensures that the laser resonant cavity can maintain perfect alignment even in the event of minor misalignment, greatly improving the long-term stability of the system.

In addition, TUNICS' optical head is entirely made of Invar alloy, which is a metal material with zero thermal expansion coefficient. Therefore, the laser can operate stably within the full specification range without any temperature control module, and has significant advantages such as instant start and low power consumption.

2. Mode Hop Free working mode

Mode hopping is the most common and difficult to predict problem in tunable lasers, characterized by sudden wavelength jumps and discontinuous scanning, which seriously affects test repeatability. The TUNICS series uses a geometric optimization scanning mechanism to ensure that the cavity length is an integer multiple of the wavelength at any time, thereby achieving continuous wavelength scanning.

TUNICS Plus further introduces active cavity length control technology to achieve mode hopping free scanning within the full tuning range (minimum 100 nm). This feature is crucial for high-resolution spectral analysis, device transmission spectrum testing, and other scenarios.

3. Internal wavelength reference system

The wavelength accuracy of an external cavity laser depends on the sub micron variation of cavity length. TUNICS Plus has a built-in high-precision wavelength reference system that can measure and calibrate the output wavelength in real time, achieving high-precision output without the need for an external wavelength meter. This not only simplifies the testing system architecture, but also reduces the complexity and cost of system integration.

ASE noise suppression: groundbreaking design of TUNICS Purity

In standard external cavity lasers, although the output is dominated by single longitudinal mode, there is still broadband amplified spontaneous emission (ASE) noise. If this noise is not effectively filtered out, it will affect the accuracy of device and amplifier testing.

TUNICS Purity adopts a new patented intracavity filtering design, which achieves deep suppression of ASE noise without sacrificing output power and wavelength stability. Its equivalent full width at half maximum (FWHM) filtering width is only 0.15 nm, making residual ASE almost unmeasurable. Compared with traditional external filter schemes, this design avoids additional insertion loss and wavelength drift issues.

TUNICS Purity's output spectrum is pure and free of ASE noise background, making it particularly suitable for direct testing of passive components such as high dynamic range optical filters, multiplexers/demulsifiers, etc.

High output power and wide tuning range

The TUNICS series maintains high power output over a wide tuning range. Typical models can provide output power exceeding+6 dBm in the spectral center region, while some models such as TUNICS Plus 10 can achieve+10 dBm. High power output helps to address power budget constraints in testing systems, improve signal-to-noise ratio, and measure dynamic range.

In terms of wavelength coverage, the TUNICS series covers the complete spectral range from 1260 nm to 1640 nm through multiple dedicated laser diodes, meeting the current and future requirements of DWDM transmission systems. among which

TUNICS Plus supports S, C, and L bands, and some models can achieve continuous mode free scanning exceeding 150 nm;

TUNICS Purity covers the S, C, and L bands (1430-1625 nm);

TUNIS-BT offers a tuning range of 80 nm, suitable for general optical platforms.

In addition, all models are equipped with Automatic Power Control (APC), which can control power fluctuations within ± 0.01 dB over time, ensuring the repeatability of test data.

Detailed explanation of TUNICS series products

1. TUNICS Plus: Flagship High Performance Tunable Laser

TUNICS Plus is the culmination of years of technical accumulation by NetTest, with the following core functions:

Active mode free control: ensuring continuous scanning across the entire frequency band;

High output power: up to+10 dBm;

Wide tuning range: with a maximum width of over 150 nm and a resolution of 1 pm;

Multiple modulation methods: supports amplitude modulation and mode locking operations;

Wavelength monitoring and external calibration: It can be linked with the wavelength meter through GPIB or RS-232 interface to achieve closed-loop wavelength control;

Sub MHz frequency fine-tuning: supports linewidth broadening (coherent control) function.

TUNICS Plus offers multiple wavelength range options, such as Sxx (short band), SC (S+C), CL (C+L), etc., to meet the testing needs of different bands.

2. TUNICS Purity: ASE noise free pure light source

TUNICS Purity has further improved the spectral purity based on TUNICS Plus:

ASE noise free output: patented intracavity filtering design;

Wavelength accuracy: ± 50 pm (internal reference);

Output power: up to+3 dBm;

Application scenario: Testing of high dynamic range devices, such as filters, AWGs, etc.

The purity of its output spectrum allows users to obtain high-precision test results without the need for additional configuration of tracking filters or spectral analyzers.

3. TUNIS-BT: Economical high-performance desktop laser

TUNICS BT offers the core features of the TUNICS series at a more compact size and more economical price:

Tuning range: 80 nm (optional 1440-1520, 1480-1560, 1520-1600, 1560-1640 nm);

Resolution: 1 pm;

Output power: Standard 0 dBm, optional+6 dBm or+10 dBm;

Applicable scenarios: General optical experimental platform, teaching and basic research and development.

4. TUNIS-OM: Modular manual tuning light source

TUNIS-OM is designed specifically for multi wavelength testing systems, supporting up to 8 modules integrated into a 19 inch chassis:

Tuning range: 70 nm (1500-1570 nm or 1530-1600 nm);

Resolution: better than 10 pm;

Modulation capability: 10 kHz to 1 GHz;

Power options: Standard>0 dBm, optional+6 dBm or+10 dBm.

Its multi turn knob design makes wavelength adjustment extremely intuitive, suitable for laboratory environments that require frequent manual wavelength adjustment.

OSICS Platform: Modular and Scalable Testing System

OSICS is a new generation modular optical testing platform launched by NetTest. Its core module, OSICS-ECL, is based on TUNICS technology and provides high-precision tunable external cavity laser output

Control mode: front panel control or IEEE-488/RS-232 remote control;

Resolution: Standard 10 pm, optional 1 pm;

Wavelength range: Same as TUNIS-BT;

Power options: 0 dBm standard, optional+6 dBm or+10 dBm;

Module mixing and matching: It can be mixed with DFB, ASE, EDFA, LD and other modules to build a multi wavelength and multi-functional testing system.

The OSICS platform is particularly suitable for automated testing systems that require multi-channel and high flexibility, such as optical transceiver module production line testing, optical amplifier performance evaluation, etc.

Application scenarios and technological value

1. DWDM system testing

The high wavelength accuracy, no mode hopping scanning, and wide tuning range of TUNICS series lasers make them an ideal choice for DWDM system testing. Whether it is channel spacing testing, filter response measurement, or gain spectrum scanning of optical amplifiers, TUNICS can provide stable and reproducible excitation light sources.

2. Analysis of Optical Device Characteristics

For devices such as optical filters, multiplexers, and demulsifiers, TUNICS Purity's pure spectrum can achieve high-precision measurements of insertion loss, isolation, polarization related loss, and other parameters without the need for additional filtering equipment.

3. Integration of automated testing systems

The TUNICS series supports GPIB and RS-232 interfaces across the entire range, and provides LabVIEW drivers for easy integration into automated testing environments. The OSICS platform further supports the mixing and matching of multiple modules to meet the construction requirements of complex testing systems.

4. Research and Teaching

TUNIS-BT has become an ideal choice for university laboratories and research institutions due to its economy and high performance. Its intuitive operating interface and stable output are suitable for teaching demonstrations in courses such as laser principles and fiber optic communication.

Summary of Technical Specifications and Options

Model tuning range, output power resolution, no mode hopping, ASE suppression, internal reference

TUNICS Plus 1260-1640 nm, maximum+10 dBm, 1 pm. Is that correct

TUNICS Purity 1430-1625 nm maximum+3 dBm 1 pm Yes Yes Yes Yes

TUNIS-BT 80 nm (multi band) maximum+10 dBm 1 pm No No No No

TUNIS-OM 70 nm maximum+10 dBm<10 pm No No No No

OSICS-ECL 80 nm maximum+10 dBm 1 pm optional No

Optional accessories include:

High power option (P6/P10)

Polarization maintaining output fiber (M)

Wide band option (WB, suitable for TUNICS Plus CL/S 1.48)

LabVIEW driver

FC-APC/FC-PC jumper

On site portable case (TUNIS-OM)