A. Müller, M. Maiwald, and B. Sumpf

Published in:

IEEE Photonics Technol. Lett., vol. 31, no. 13, pp. 1120-1123 (2019).

Abstract:

A compact, micro integrated, diode laser-based dual-wavelength master oscillator power amplifier at 785 nm is presented. Laser emission from a Y-branch distributed Bragg reflector laser is coupled into a tilted ridge waveguide amplifier on a 5 × 25 mm² micro optical bench. At 25°C and 20 mW pump power, an optical output power of 0.5 W is obtained. The corresponding emission wavelengths are 784.62 and 785.24 nm, resulting in a spectral distance of 10 cm^-1. The measured spectral bandwidths and side mode suppression ratios are 0.02 nm (0.3 cm^-1) and 30 dB, respectively. At both wavelengths beam propagation parameters of 1.3 (M²_4σ) are obtained. This allows for efficient dual-wavelength single-mode fiber coupling. In addition, the device does not show any effects from optical feedback. It neither shows a lateral spatial tilt of the far field intensity distributions for the two wavelengths, previously reported for single Y-branch diode lasers. Based on these parameters, the device is suitable for demanding applications such as shifted excitation Raman difference spectroscopy or confocal Raman microscopy.

Index Terms:

Diode laser, master oscillator power amplifier, ridge waveguide, distributed Bragg reflector, dual-wavelength, Raman spectroscopy, shifted excitation Raman difference spectroscopy.

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