Selim Dogru

0.77-V drive voltage electro-optic modulator with bandwidth exceeding 67 GHz.

A 0.77-V drive voltage (V(π)) electro-optic modulator with bandwidth exceeding 67 GHz is described. Modulator is a compound semiconductor device fabricated using substrate removal technology. This allows placement of metal electrodes on both sides of an optical waveguide containing a p-i-n diode. Hence ohmic losses are reduced significantly. Electrode gap is essentially the same as i layer thickness, which can be kept very uniform and small. Waveguide core also contains a MQW, which improves electro-optic efficiency. Lack of p doping in the waveguide and large detuning between MQW absorption peak and operating wavelength keep the propagation loss low. Large size of the waveguide also helps to keep coupling loss low. Modulator is designed as a traveling wave device using the loaded line approach, which is used for velocity matching. Combination of these approaches yields a device with the lowest V(π) and widest bandwidth.

0.2 V Drive Voltage Substrate Removed Electro-Optic Mach–Zehnder Modulators With MQW Cores at 1.55 μm

Novel electro-optic modulators in compound semiconductor epilayers using substrate removal techniques are reported. Epilayer consists of a p-i-n junction in which i layer is composed of an InGaAlAs/InAlAs MQW. This creates an optical mode with very strong vertical confinement and overlapping very well with the large electric field of the reverse biased p-i-n junction. This approach combined with the large quadratic electro-optic coefficient due to MQW improves efficiency of modulation significantly. Mach-Zehnder electro-optic modulators fabricated using this approach has 0.2 V (0.6 V) Vπ for 3 (1) mm long electrodes at 1.55 μm under push pull drive corresponding to record modulation efficiency of 0.06 V·cm.

InGaAlAs/InAlAs multi quantum well substrate removed electro-optic modulators

Substrate removed Mach-Zehnder electro-optic modulators with InGaAlAs/InAlAs MQW cores are reported. Devices have 0.36 V-cm drive voltage length product and 2 pF/cm capacitance making them suitable for very low voltage and wide bandwidth operation.

Electrodes for wide-bandwidth substrate-removed electro-optic modulators

Traveling wave electrodes suitable for wide bandwidth substrate removed electro-optic modulators containing buried electrodes are reported. Experimental results indicate modulator bandwidths in excess of 35 GHz along with sub volt drive voltage.

Ultra-low voltage substrate-removed mach-zehnder intensity modulators with integrated electrical drivers

Integration of traveling wave electrical drivers with wide bandwidth ultra-low Vpi substrate removed electro-optic modulators is studied. 1.5 mm long device with 0.1 V Vpi, 50 Omega input impedance and 15 GHz bandwidth seems possible.

Traveling Wave Electrodes for Substrate Removed Electro-Optic Modulators With Buried Doped Semiconductor Electrodes

This paper reports theoretical and experimental studies of traveling wave electrodes suitable for wide bandwidth operation of ultra-low voltage substrate removed compound semiconductor electro-optic modulators. These modulators use submicron epitaxial layers removed from their substrates and contain buried electrodes made out of doped semiconductors. This approach enables very uniform submicron electrode gap resulting in ultra-low voltage operation. Traveling wave electrodes suitable for wide bandwidth and low voltage operation are designed using loaded line approach. Electrode capacitance and resistance are reduced significantly using staircase waveguides and n-i-p-i-n epitaxial layer designs. A very accurate modeling of the electrode is introduced. Such electrodes are fabricated and characterized up to 35 GHz. Experimental and modeling results are found to agree very well, making the design of such electrodes possible. Theoretical and experimental results show that subvolt modulators with electrical to optical bandwidths in excess of 35 GHz are possible.

Design and Optimization of Ultra Low Voltage, Wide Bandwidth Substrate Removed Electro-Optic Modulators

Design and optimization of wide bandwidth ultra low voltage substrate removed electro-optic modulators is described. 30 GHz bandwidth, 50 Ω impedance with Vπ of 0.2 V should be possible.

InP Based Very-Low Voltage Electro-optic Intensity Modulators in Conventional Waveguides

Very-low drive voltage intensity modulators were fabricated in InP epitaxial layers containing MQW cores using conventional waveguides and processing. 1 cm long electrode devices have one arm driven of 1.6 V at 1550 nm.

Wide Bandwidth Design of Ultra-Low Voltage Substrate-Removed Electro-Optic Mach-Zehnder Intensity Modulators

Wide bandwidth design of recently demonstrated 0.3 V Vπ substrate removed electro-optic modulators is described. 30 GHz bandwidth with Vπ substantially lower than 1 V should be possible.

Sub-volt drive voltage, ultra wide bandwidth substrate removed electro-optic modulators

This paper reports for the first time a 0.77 V Vπ modulator with larger than 67 GHz bandwidth. Such a device can be directly driven without an external modulator driver and enables applications that deliver ultra wide bandwidths needed in fiber optic communications.