A 780 nm-range 40 channels vertical-cavity surface-emitting laser (VCSEL) array was developed as a writing light
source for printers. A 15° off missoriented GaAs substrate, an aluminum-free GaInAsP/GaInP compressively-strained
multiple quantum well and an anisotropic-shape transverse-mode filter were employed to control polarization
characteristics. The anisotropic-shape transverse-mode filter also suppressed higher transverse-mode and enabled high-power
single-mode operation. Thus, orthogonal-polarization suppression-ratio (OPSR) of over 22 dB and side-mode
suppression-ratio (SMSR) of 30 dB were obtained at operation power of 3mW at same time for wide oxide-aperture
range below 50 μm<sup>2</sup>. Moreover, a thermal resistance was reduced for 38% by increasing a thickness of high thermal
conductivity layer (3λ/4-AlAs layer) near a cavity. By this structure, a peak-power increased to 1.3 times. Moreover, a
power-fall caused by self-heating at pulse-rise was decreased to 10% and the one caused by a thermal-crosstalk between
channels was decreased to 46%. The VCSEL array was mounted in a ceramic package with a tilted seal glass to prevent
optical-crosstalk caused by other channels. Thus, we achieved stable-output and high-quality beam characteristics for
long-duration pulse drive.
We propose an optically controllable device Photorefractive Connection Module (PRCM) for free-space optical interconnection between boards. The optical signal composed of a large number of spatially divided channels passes through the photorefractive material which is core of PRCM. In the photorefractive material, diffraction gratings are induced only where the control beam and the pump beam are illuminated. The signal beams in desired spatial channels can be diffracted by setting an appropriate pattern of the control beam and extracted by separating from the control beam with a beam splitter. In this study, we use organic photorefractive polymer PATPD as the photorefractive material. Diffraction efficiency of PATPD is comparable with thick inorganic crystals although the thickness of PATPD is less than 1/10 of these crystals. Thin gratings have a large advantage for PRCM because the thickness of the gratings causes large crosstalk between spatial channels. In addition, the constraint of phase matching is reduced because the phase mismatch is proportional to the thickness of the material. The decrease of the phase mismatch provides large allowance for misalignment of incident angle of beams; therefore it becomes easy to adjust incident angles. We reveal the relation of diffraction efficiency to angular difference of PATPD by analysis and experiment. Diffraction efficiency decreases by half at the difference of 0.5<sup>o</sup>, which is about ten times larger than that of thick crystals. We demonstrate that it is possible to extract the signal beams in desired channels and reconfigure the extraction pattern according to optical control by using PATPD.