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.