The TEC-120 series are tunable external cavity laser diodes based on a Littrow cavity. These lasers provide wavelength tunability with central wavelengths in the UV, Blue, red, or infrared regions of the spectrum.
Output powers of up to 200mW are available.
The tuning range is diode dependent. Adjustment screws built into the cavity manually tune the wavelength. Finer adjustment of the cavity for fine wavelength tuning is achieved through the built in Piezo actuator.
The coarse tuning range is typically 1-5% of the centre wavelength (5-60nm depending on the diode) and the fine wavelength tuning is typically of the order of 100GHz. The mode hop free tuning range of the TEC-120 series is approximately 40GHz.
Peak output powers range from 1-200mW. These depend on the initial centre wavelength of the laser diode wavelength and the wavelength that it is tuned to. Output power varies with wavelength and tends to decrease as the laser is tuned away from the central wavelength. This variation approximates to a broadened Gaussian function. Historical tuning curves showing the output power achieved across a wavelength spectrum are available upon request.
The TEC series of external cavity laser diodes come in two different cavity configurations; Littrow and Littman. Littrow cavity designs tend to generate higher power whereas Littman cavity lasers have wide wavelength tuning and narrower linewidths.
All of the lasers in the TEC-120 series are based upon a Littrow cavity. The laser linewidth is approximately 2MHz over 1msec.
This series has an enhanced cavity design. Laser emission occurs from the rear facet, to give a number of improvements:
- Strong coupling of the laser diode to the external cavity results in excellent repeatability
- Side mode suppression is improved significantly (55dB typical)
- Output power is increased
- Total tuning as well as the mode-hop free tuning range are improved for many wavelengths
- Beam walk when wavelength tuning is reduced to negligible levels.
Each laser diode used in the range is antireflection coated using a proprietary process to achieve a facet reflectivity of less 1x10e-4. The low reflectivity ensures that maximum cavity coupling takes place. This results in superior line narrowed performance and cavity stability. This in turn provides lower optical noise, output power stability and alignment tolerance.
Each system comes with a benchtop controller (code:Pilot). This controller is compatible with single phase 240VAC (13A) mains electricity. It includes a key switch, emergency stop and interlock interface. The unit is fully featured providing a range of different adjustment parameters of the laser via the menu driven software. An RS232/USB interface allows remote control of the system via PC. The controller also provides fine adjustment of the cavity via the Piezo actuator.
The output beam profile of these lasers is elliptical and astigmatic. The laser head is provided with a fixed collimation lens. Beam circularisation optics or fibre coupling (multimode or singlemode fibre) are also available as options. An optical isolator can be incorporated as an additional option.