Amplifying laser diodes
For a variety of applications the output power of single-mode diode lasers is not sufficient. It is limited, because high intensities on their small facets can cause COD (catastrophic optical damage). Also, high current densities lead to degradation and limited lifetime.
Specially shaped semiconductor optical amplifiers, or Tapered Amplifiers (TAs), serve to increase the power available from single-mode diode lasers in a Master Oscillator Power Amplifier (MOPA) configuration. The master laser beam is coupled into the single-mode channel of the TA chip, which mainly acts as a spatial mode filter. In the subsequent tapered section, this “perfect” beam is further amplified in single pass while freely diverging in the tapered plane and being confined in the orthogonal plane. After exiting the large AR-coated output facet of the amplifier chip, this light can be shaped again into a high-quality beam with similar spectral quality as before. The output facet of tapered amplifiers is much larger and allows for much higher output powers without COD. Also the active chip area is larger and therefore the current density smaller, allowing for higher amplifier currents. Typically, a small-signal gain of up to 20 dB and maximum output levels of up to 4 W can be achieved.
TOPTICA offers several amplifier and laser systems based on tapered amplifiers. The TA pro is the flagship, containing a tunable diode laser as the master laser combined with a suitable tapered amplifier – all in pro technology. It combines the narrow linewidth and low noise properties of TOPTICAs master lasers with the high power and excellent beam quality of our tapered amplifiers.
BoosTA pro is a high-quality amplifier system that takes the light from a seed source and amplifies it up to 4W of power.
TOPTICA is constantly working together with renowned partners on TA chip development. The main aims of these initiatives are:
- to provide TA chips at new wavelengths
- to improve the output power of TA chips
- to maintain the availability of TA chips
Examples for successful developments are the extension of the NIR wavelength limit from 1083 nm to now 1357 nm by several novel TA chips with multi-Watt output power, a power increase from 3W to 4W at 780 nm, the introduction of new TA chips for amplification around 690 nm and the re-establishment of TA chips that reliably provide 500 mW at 670 nm.