Hayato Sano

Athermal 850 nm Vertical Cavity Surface Emitting Lasers with Thermally Actuated Cantilever Structure

We demonstrate the first athermal and tunable operation of 850 nm vertical cavity surface emitting lasers (VCSELs) using a thermally actuated cantilever for compensating the temperature dependence of lasing wavelengths. A novel micromachined air-gap cavity with an anti-reflection AlxOy layer which can be formed by a wet-oxidation process is proposed and fabricated. The temperature dependence is as low as 0.002 nm/K, which is 40 times smaller than that of conventional VCSELs. In addition, the fine wavelength tuning of 0.8 nm is also realized with changing injection current.

Athermal and tunable operations of 850 nm vertical cavity surface emitting lasers with thermally actuated T-shape membrane structure

We demonstrate the athermal operation and the wavelength tuning of 850 nm GaAs-based vertical cavity surface emitting lasers with a thermally actuated cantilever structure. The thermal actuation of a top distributed Bragg reflector mirror enables us to compensate the temperature drift of lasing wavelengths. The temperature dependence of lasing wavelengths could be controlled from −0.011 nm/K to −0.18 nm/K by changing the cantilever length. In addition, a T-shape membrane structure was introduced for efficient electro-thermal tuning. A small temperature dependence of −0.011 nm/K and wavelength tuning of 4 nm were obtained.

Tuning Characteristics of Monolithic MEMS VCSELs With Oxide Anti-Reflection Layer

We demonstrate a micromachined tunable vertical-cavity surface-emitting laser with a monolithically formed anti-reflection (AR) layer for highly efficient electro-thermal wavelength tuning. The AR layer is formed by the lateral oxidation of an aluminum-rich AlGaAs layer and no extra process is needed. We fabricated a micromachined GaAs vertical-cavity surface-emitting laser and measured its wavelength tuning characteristic. The measurement result shows that the oxide layer functions as an AR layer for linear and efficient tuning characteristics. A large negative temperature dependence of wavelength from -0.24 to -2.0 nm/K was demonstrated using a thermally actuated cantilever for efficient electro-thermal wavelength tuning. An electro-thermal tuning efficiency of -2.3 to -4.8 nm/mW was obtained.

Proposal of gain-matched VCSELs with a thermally actuated MEMS structure for wide temperature operations

We propose a novel gain-matched VCSEL with a thermally actuated cantilever structure, which enables the lasing wavelength to be matched with a gain-peak wavelength even under wide temperature changes. The proposed structure includes an AlxOy layer in an air-gap cavity, which results in the increase of the temperature dependence of lasing wavelengths. The modeling result shows a potential of wide temperature operations of over 200K.

Transverse mode control of VCSELs with high contrast sub-wavelength grating functioning as angular filter

We present the design of high-contrast sub-wavelength grating functioning as angularly selective filter for the transverse-mode-control of VCSELs. Highly angular dependent reflection characteristics can be obtained for avoiding high-order transverse modes in large-area VCSELs.

Wavelength tuning and controlled temperature dependence in vertical-cavity surface-emitting lasers with a thermally and electrostatically actuated cantilever structure

We demonstrate the wavelength tuning and the control of its temperature dependence in 850 nm GaAs vertical cavity surface emitting lasers (VCSELs) using a thermally and electrostatically actuated cantilever structure. The temperature dependence can be controlled from +0.035 to −0.14 nm/K by changing the length of a micromachined cantilever, which can be electrostatically actuated for wavelength tuning. Continuous wavelength tuning over 36 nm was obtained keeping almost constant temperature dependence. The result indicates a possibility of realizing widely-tunable VCSELs with engineered temperature dependence.

Controlled temperature dependence of lasing wavelength of VCSELs with a thermally actuated cantilever

We demonstrate the first widely controlled temperature dependence of lasing wavelength of VCSELs using a thermally actuated cantilever. The temperature dependence of wavelengths is successfully controlled from −0.15nm/K to 0.32nm/K.

Proposal of multi-wavelength integration of athermal GaAs VCSEL array with thermally actuated cantilever structure

We propose a multi-wavelength and athermal VCSEL array with thermally-actuated cantilevers. The lithography-defined cantilever structure enables on-chip multi-wavelength integration. The experiment shows the wavelength spacing of 20 nm for 2-ch VCSEL array with different cantilever lengths.

Wavelength trimming of MEMS VCSELs for post-process wavelength allocation

We demonstrate the wavelength trimming of MEMS VCSELs by etching the cantilever-shaped top mirror using FIB. This technique can be used for the post-process precise wavelength allocation of athermal MEMS VCSELs. Experimental results show a possibility of realizing both red-shift and blue-shift wavelength changes by choosing the etching area of the cantilever.

Electro-thermally tunable 850nm VCSELs with metal/semiconductor thermally actuated mirror

We report on an electro-thermally tunable 850nm VCSEL, exhibiting a large negative wavelength drift of 2.0nm/K. Continuous and linear wavelength tuning of 25 nm was obtained with heating power of 9.4 mW.