High-power 940 nm DFB laser diode with large optical cavity

Area of Science:

• Optoelectronics
• Semiconductor Lasers
• Nanofabrication

Background:

• High-power laser diodes require stable wavelengths and narrow linewidths for diverse applications.
• Existing laser diode designs often face limitations in power output, spectral stability, and operational temperature range.

Purpose of the Study:

• To develop a high-power laser diode with a stable wavelength and narrow linewidth around 940 nm.
• To investigate the performance of a first-order distributed feedback (DFB) grating integrated into an asymmetric large-cavity laser diode.

Main Methods:

• Fabrication of a nearly sinusoidal first-order grating using ultraviolet (UV) nanoimprint lithography, inductively coupled plasma (ICP) dry etching, and wet polishing.
• Integration of the DFB grating into an asymmetric large-cavity laser diode structure.
• Characterization of laser diode performance under continuous-wave (CW) and quasi-continuous operation, including output power, spectral linewidth, efficiency, and temperature stability.

Main Results:

• Achieved a maximum output power of 24.8 W with a full width at half maximum (FWHM) of 0.4 nm at 25°C under CW conditions.
• Reached a peak wall-plug efficiency of 56% at an output power of 10.7 W.
• Demonstrated wavelength locking to the DFB grating over a wide temperature range (-10°C to 110°C) with a low temperature coefficient of 0.062 nm/°C.

Conclusions:

• The integrated DFB grating design enables high-power, spectrally stable laser diode operation around 940 nm.
• The device exhibits excellent temperature stability and high efficiency, making it suitable for demanding applications.
• The fabrication methods employed are effective for producing high-performance DFB laser diodes.