The TEC-520 series are external cavity laser diodes based upon a Littman-Metcalf cavity.
These lasers provide wavelength tunability, with central wavelengths in the red, or infrared regions of the spectrum.
Output powers of up to 100mW are available.
The tuning range is diode dependent. Two tuning ranges are provided. Adjustment screws built into the cavity manually tune the wavelength. Motorised adjustment of the coarse wavelength tuning is an option with this series. 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 >100GHz. The mode hop free tuning range of the TEC-520 series is around 100GHz.
Peak output powers range from 1-100mW. 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 are provided 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 linewidth.
All of the lasers in the TEC-520 series are based upon a Littman cavity. The laser linewidth is approximately 1MHz over 1msec.
This series benefits from an enhanced cavity design. Laser emission occurs from the rear facet, yielding 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 typ)
- Output power is increased
- Total tuning range 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). The 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.
Optical isolators are recommended with this series.