Semiconductor Photonic Switch Research Articles

Near infrared integrated photonic switches for portable quantum sensors

A novel integrated semiconductor photonic switch, based on carrier-induced refractive index changes, has been designed and fabricated for use at near infrared wavelengths (890-920 nm, 750-780 nm and 745-775 nm). These switches are intended for use in quantum sensors which rely on the spectroscopy of caesium, rubidium or potassium atoms respectively. The beam-steering properties of the 890-920 nm device are presented and its extinction ratio measured to be 13.4 dB. This measurement was limited by coupling efficiency. Subsequent changes made to the testing equipment include the implementation of an automated testing routine. This new experimental setup will facilitate the full characterisation of the 890-920 nm device and the newly fabricated optical switches, designed for operation in the wavelength ranges 750-780 nm and 745-775 nm respectively.

A reconfigurable multimode interference splitter for sensing applications

A reconfigurable multimode interference (MMI) coupler is demonstrated. The device operates by modifying the phase of the multiple images that are formed around the midpoint of the MMI section. This modifies the properties of the following set of images, and light can be directed to a specific output waveguide, which is therefore ideal to develop a reconfigurable MMI coupler. In our device the phase change is achieved by current injection, and therefore minimizing current spreading is crucial for optimal operation. A zinc in-diffusion process has been implemented to selectively define p–n regions and effectively regulate current spreading by controlling the depth of the zinc doping. Using this process, a reconfigurable 3 dB MMI coupler has been fabricated. Our experimental results revealed that the device can be easily set to a perfect 3 dB splitter using only 0.7 mA of current injection. In addition, the device can be adjusted all the way from a 90:10 to a 30:70 splitting ratio. The results are very encouraging since, to our knowledge, this degree of tuning of the optical power has never been experimentally demonstrated in MMI devices. Furthermore, this concept can easily be applied to a wide variety of semiconductor photonic switches that operate on MMI effects.

InGaAsP/InP Multi-Mode Interference Photonic Switches for Monolithic Photonic Integrated Circuits

InGaAsP/InP semiconductor photonic switches using multi-mode interference (MIPS) are proposed for monolithic photonic integrated circuits. Changing the refractive indices of index-modulated regions located in the center of a multi-mode waveguide, controls its switching functions. It is predicted from calculations by an FD-TD (finite difference time domain) method that these devices can operate in various kinds of output schemes with typical device dimensions of about 8 µm width and 540 µm length. 1×2 InGaAsP/InP MIPS's with a high-mesa structure have been fabricated, and fundamental switching characteristics were measured. At the preliminary stage, switching was observed at 20 mA current injection with about 37% extinction ratio. Switching efficiency and cross talk of the MIPS can be improved by optimizing the device dimensions and structure. The flexibility of setting the index-modulated regions suggests versatile operation of the MIPS, such as a photonic space division switch, a variable power splitter, or as an optical modulator.

Characteristics of 4×4 photonic switch array with gain and high contrast

A two-dimensional semiconductor photonic switch array with a new operating principle based on the change of the gain coefficient in the GaAs crystal is reported. This switch realizes direct amplification and absorption of the optical signal and features optical gain of 4 dB, contrast of 9.6 dB, applied voltage of 2.2 V, and a simple planar structure. This array is applicable to photonic parallel data transmission systems.