Dual-Frequency VECSEL at Telecom Wavelength for Sensing Applications

We aim at realizing an optically-pumped, dual-frequency VECSEL at telecom wavelength (1.5 µm) with a frequency difference in the radio-frequency (RF) range (around 11 GHz), to be used in a sensor unit based on Brillouin scattering in optical fibers. Laser emission of two orthogonally-polarized cavity modes with a controlled frequency difference is obtained by inserting a birefringent crystal in the VECSEL cavity. We have examined the influence of the different intra-cavity elements on the laser emission. It is shown that optimizing the free spectral range and the bandwidth of the intra-cavity Fabry-Perot etalon is of practical importance to achieve a stable single longitudinal laser emission for each of the two orthogonal polarizations. The optimization of the output power has also been investigated and it is concluded that up to 100 mW output power can be expected by adjusting the reflectivity of the output coupling mirror of the VECSEL cavity. The achievement of a highly-stable frequency difference is crucial for sensing applications. For this reason the influence of different parameters on the stability of the dual-frequency emission have been studied. It is concluded that mechanical vibrations are the main cause of the RF signal instability in our free-running VECSEL cavity. The design of a compact or mono-block cavity may allow to meet the stability requirements for our sensors.

[1]  S. Bouchoule,et al.  Cost-Effective Thermally-Managed 1.55-$\mu{\rm m}$ VECSEL With Hybrid Mirror on Copper Substrate , 2012, IEEE Journal of Quantum Electronics.

[2]  F. Bretenaker,et al.  Dual tunable wavelength Er,Yb:glass laser for terahertz beat frequency generation , 1998, IEEE Photonics Technology Letters.

[3]  Mehdi Alouini,et al.  Experimental demonstration of a tunable dual-frequency semiconductor laser free of relaxation oscillations. , 2009, Optics letters.

[4]  Syamsundar De,et al.  Class-A dual-frequency VECSEL at telecom wavelength. , 2014, Optics letters.

[5]  Anthony W. Brown,et al.  Spatial resolution enhancement of a Brillouin-distributed sensor using a novel signal processing method , 1999 .

[6]  M Brunel,et al.  Tunable optical microwave source using spatially resolved laser eigenstates. , 1997, Optics letters.

[7]  I. Sagnes,et al.  Coherent Dual-Frequency Emission of a Vertical External-Cavity Semiconductor Laser at the Cesium ${\rm D}_{2}$ Line , 2012, IEEE Photonics Technology Letters.

[8]  T. Horiguchi,et al.  Coherent self-heterodyne detection of spontaneously Brillouin-scattered light waves in a single-mode fiber. , 1993, Optics letters.

[9]  Hamzah Arof,et al.  Advances in Optical Fiber Technology: Fundamental Optical Phenomena and Applications , 2015 .

[10]  Isabelle Sagnes,et al.  Thermal optimization of 1.55 μm OP-VECSEL with hybrid metal–metamorphic mirror for single-mode high power operation , 2008 .

[11]  Sean Staines,et al.  Novel distributed fiber temperature and strain sensor using coherent radio-frequency detection of spontaneous Brillouin scattering , 2007, 2007 Quantum Electronics and Laser Science Conference.

[12]  I. Sagnes,et al.  Measurement of the coupling constant in a two-frequency VECSEL. , 2010, Optics express.