Noise generator

Optical Noise Generator Simulating Random Light Sources in Optical Experiments

In the research and development of optoelectronic systems, a laser source is not always the ideal choice. Experiments that require testing a device’s response under noise conditions, verifying linearity, or examining the broadband characteristics of a sensor often need a special kind of source: the Optical Noise Generator.

This device produces light with random fluctuations in intensity and spectrum, allowing users to simulate real-world signal conditions.

Operating Principle and Spectral Characteristics

An optical noise generator typically relies on spontaneous emission or optical amplification in nonlinear media.

The initial light source (commonly a modulated LED or diode laser) is diffused through scattering materials or highly noisy optical fibers, generating a broad light spectrum with energy density distributed probabilistically instead of remaining fixed as in a laser.

Modern devices allow:

- Adjustment of spectral range from visible (400-700 nm) to IR (1000-1600 nm).

- Selection of output power levels suited to specific experiments.

- Maintenance of phase and amplitude stability at sufficiently low levels to mimic realistic noise while ensuring repeatable results.

- The use of incoherent, non-directional light, an important feature for eliminating interference effects in pure intensity or energy distribution measurements.

Role in Optical Measurement and Testing

In practice, performance testing of optical devices—from light sensors and photodiodes to fiber-optic transmission systems—requires simulated noisy signals to evaluate:

Linearity and saturation limits of photodetectors.

Signal-to-noise ratio (SNR) in amplification or transceiver circuits.

Spectral responsivity of optical components, revealing coating or material structure deviations.

System stability under background noise influence.

With its ability to generate continuous and uniformly distributed spectra, the optical noise generator is also used for optical filter calibration, multimode fiber attenuation testing, and environmental noise emulation in high-speed optical links.

Design, Structure, and Performance Factors

Modern optical noise generators feature compact metal modules with high electromagnetic shielding. Key technical aspects include:

- Number of Taps (outputs): allowing multi-channel signal distribution for parallel or comparative measurements.

- Spectral width and flatness: the flatter the spectrum, the more uniform the verification across multispectral devices.

- Output power level and temporal stability: directly affecting experiment repeatability.

- Mechanical compatibility: supports M6 or ¼"20 mounts for stable integration on optical tables, ensuring precise beam alignment.

Advanced laboratories often prefer modules compliant with international optical standards, enabling easy integration with photodiodes and optical power meters.

Recommended Model: Thorlabs NE Series Optical Noise Generator

Within this product category, the Thorlabs NE Series is widely used by laboratories, research institutes, and metrology centers.

Their key strengths include high spectral stability, robust construction, and compatibility with standard optical mounts and setups—making them suitable for both industrial environments and academic research applications.