Narrow linewidth lasers, or lasers that have a small optical linewidth, are usually single-frequency, with low RIN and high spectral purity as a result of low phase noise.
The most common types of narrow linewidth lasers are distributed feedback laser diodes and distributed Bragg reflector lasers. Ultra narrow linewidths can be achieved by using a single-mode fiber that contains a narrow-bandwidth fiber Bragg grating in a resonator. Special fiber Bragg grating used in distributed feedback lasers also allows for a narrow linewidth of a few kilohertz. Narrow linewidth lasers with high output powers can be achieved in the form of longer distributed Bragg reflector lasers. Other lasers that have a narrow optical spectrum include diode-pumped solid-state bulk lasers and external-cavity diode lasers.
Several difficulties emerge in the manufacturing of narrow linewidth lasers and ultra narrow linewidth lasers. First of all, achieving single-frequency operation is crucial to get narrow linewidth; the goal is a stable single-frequency operation without mode hopping over a relatively long period of time.
Secondly, minimizing noise influences from external sources is problematic. There are multiple ways of resolving a problem of external noise influences. A stable resonator setup with a protection against vibration may be used. Certain lasers require specific solutions; for example, a low-noise current source should be implemented into the operation of electrically pumped lasers; optically pumped laser should have a low-intensity noise pump source. A Faraday isolator is often used to avoid optical feedback.
Thirdly, the laser itself, its design in particular, should be manufactured with a goal of minimizing laser and phase noise. Long resonator and a high intracavity optical power can be beneficial to construct a narrow linewidth laser.
Narrow linewidth lasers have a variety of applications: strain and temperature fiber-optic sensors, gas detection, LIDAR, wind speed measurements. Ultra-narrow linewidth lasers are used in optical frequency metrology.
If you would like to buy Optromix narrow linewidth single frequency laser, please contact us at info@optromix.com or +1 617 558 98 58.
