Low Noise Semiconductor Lasers
What Are Low Noise DFB Semiconductor Lasers?
A Distributed Feedback (DFB) semiconductor laser is an advanced type of light emitting diode (LED) that uses a grating structure built directly into the laser’s semiconductor chip to achieve single-wavelength operation. Just like electronics chips, it is fabricated on wafers, where various layers of materials are deposited and etched away. The semiconductor material is doped to create a p-n junction, which means it has a positive (p-type) side and a negative (n-type) side. When a voltage is applied across the LED, electrons from the n-type side and holes (positive charge carriers) from the p-type side are pushed towards the junction. At the p-n junction, electrons and holes recombine. When an electron falls into a hole, it loses energy which is released in the form of a particle of light called photon. The color of the light depends on the energy gap of the semiconductor material.
To improve the spectral purity of an LED, a DFB laser has a grating (a periodic variation in the refractive index) embedded along the length of the laser cavity, acting as a distributed reflector. This grating provides selective feedback for specific wavelengths, ensuring that only a narrow spectral range is amplified. By suppressing other modes of oscillation, the DFB laser achieves single-mode operation, emitting light at a single wavelength.
Why Choose Low Noise DFB Semiconductor Lasers?
The grating structure in the DFB helps stabilize the wavelength of the laser, reducing the likelihood of mode hopping (sudden jumps between different wavelengths), which often happen with external cavity lasers. The single-mode operation and reduced mode hopping contribute to a very narrow-linewidth, meaning the laser emits light with a very pure and stable wavelength. It can maintain its performance at various temperatures, without mode hops. A Narrow-Linewidth Distributed Feedback Laser Diode with Unique Frequency Modulation Response | Webinars | Photonics Spectra
While fiber lasers are composed of several optical components making them complex, big and expensive, DFB lasers are small, affordable and are produced in volume with thousands of lasers per wafer. The relative intensity noise of fiber lasers is also orders of magnitude above semiconductor lasers, which is often an issue for high-end interferometric sensing applications. A DFB laser is also an extremely efficient device, as a big percentage of the drive current is converted into photons.
A DFB Laser Diode with Unique Properties
Our advanced low-noise laser technology features a proprietary distributed feedback (DFB) design, delivering ultra-narrow linewidths below 20 kHz and superior frequency modulation (FM) performance. This design achieves exceptional modulation linearity, ideal for high-resolution FMCW LiDAR systems, while supporting high-performance frequency locking and optical phase-locked loops, crucial for advanced fiber sensing applications.
Our low-noise laser solutions are driving the next generation of cost-effective, coherent sensing technologies.
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