High Performance Evanescent Edge Coupled Waveguide Unitraveling-Carrier Photodiodes for>tex<$≫$>/tex<40-Gb/s Optical Receivers

A new phototransistor with uni-travelling-carrier and optically gradual coupling properties

“…Up to 13.6 mA emitter current was obtained when input 1.3 mW optical power, which relates to external optoelectronic response of 10.46 A/W. Given the appropriate external quantum efficiency of 20% (which is limited mainly by cou− pling loss) and the wavelength effect mentioned above, the external optoelectronic response higher than 52 A/W can be obtained, for our ECTT−DHPT fabricated this value is much higher than that of ever reported (1 A/W) in a photodiode [25]. It should be noted in the plot that there is a good linear range of emitter current versus optical input power from 0.8 mW to 1.2 mW.…”

Ultrafast photodetectors and receiver

“…The compression curve is quite constant over the lower-to-mediate power range up to +8 dBm, which compares favorably with UTC-type (uni-traveling-carrier) photodiodes, which often show an increasing RF responsivity when the input power is raised from low to medium values [19].…”

“…Owing to the monolithically integrated taper, which adapts the fiber circular beam profile to the waveguide optical profile, the misalignment tolerances for fiber-chip coupling amount to about ±2 mm for a 1-dB coupling loss. These rather relaxed tolerance values are twice as high as for edge-coupled waveguide photodiodes for the critical y-direction of the fiber-chip coupling [19]. Hence a cheaper packaging process and a better long-term stability can be expected.…”

High-Power RF Uni-Traveling-Carrier Photodiodes (UTC-PDs) and Their Applications

“…The use of dual-depletion region (Jun et al, 2006) is also effective in this modification to keep the high operation speed. Another way to improve the responsivity with the high operation speed maintained is to employ an external structure to guide the input light to the absorption layer at different angle, such as waveguide structure (Muramoto et al, 1998), evanescently coupled structure (Achouche et al, 2004), velocity-matched distributed structure (Hirota et al, 2001), refracting facet structure (Fukano et al, 1999), and total reflection structure (Ito et al, 2000c).…”