David A. Tulchinsky

High-saturation-current charge-compensated InGaAs-InP uni-traveling-carrier photodiode

Charge compensation is utilized in an InGaAs-InP uni-traveling-carrier photodiode to mitigate the space-charge effect. A 20-/spl mu/m-diameter photodiode achieved a bandwidth of 25 GHz and large-signal 1-dB compression current greater than 90 mA; the output power at 20 GHz was 20 dBm. A smaller /spl sim/100-/spl mu/m/sup 2/ photodiode exhibited a bandwidth of 50 GHz and large-signal 1-dB compression current greater than 50 mA. The maximum RF output power at 40 GHz was 17 dBm.

High-saturation current wide-bandwidth photodetectors

This paper describes the design and performance of two wide-bandwidth photodiode structures. The partially depleted absorber photodiode utilizes an absorbing layer consisting of both depleted and undepleted In/sub 0.53/Ga/sub 0.47/As layers. These photodiodes have achieved saturation currents (bandwidths) of >430 mA (300 MHz) and 199 mA (1 GHz) for 100-/spl mu/m-diameter devices and 24 mA (48 GHz) for 100-/spl mu/m/sup 2/ area devices. Charge compensation has also been utilized in a similar, but modified In/sub 0.53/Ga/sub 0.47/As-InP unitraveling-carrier photodiode design to predistort the electric field in the depletion region in order to mitigate space charge effects. For 20-/spl mu/m-diameter photodiodes the large-signal 1-dB compression current and bandwidth were /spl sim/90 mA and 25 GHz, respectively.

High-saturation-current InP-InGaAs photodiode with partially depleted absorber

A high-saturation-current InGaAs photodiode (PD) with a partially depleted absorber is demonstrated. Optical responsivity of 0.58 A/W and over 1.1 W of dissipated electrical power is achieved. Small signal compression current of 110 and 57 mA is measured at radio-frequency bandwidths of 1 and 10 GHz, respectively. This continuous photocurrent is believed to be the highest reported value for a p-i-n InGaAs PD at these bandwidths.

High-Current Photodetectors as Efficient, Linear, and High-Power RF Output Stages

Recent progress in high-current photodiodes now makes it possible to efficiently generate over 26 dBm of RF power directly from the output of a photodiode. This paper describes two photodetector designs which demonstrate excellent large- and small-signal behavior. Maximum small-signal compression currents have increased to over 700 mA at 300 MHz. Output RF power amplifier stage efficiencies of over 45% (class AB operation) and 35% (class A) have been achieved from 0.3 to 6 GHz with RF power outputs over 26 dBm. The linearity figure of merit (LFOM) is also shown to be greater than 50, leading to the possibility of implementing very high linearity RF power amplifiers in the future.

Photodetector Nonlinearities Due to Voltage-Dependent Responsivity

A newly quantified photodiode nonlinearity is derived from a previously known bias voltage-dependent responsivity. For an InGaAs p-i-n photodiode, measured harmonic distortion is shown to be dominated by this derived nonlinearity mechanism. It is also shown that electron ionization in the depletion region of the photodiode is the source of the voltage-dependent responsivity.

A comparison of front- and backside-illuminated high-saturation power partially depleted absorber photodetectors

A systematic study of high-saturation-current p-i-n In/sub 0.53/Ga/sub 0.47/As photodiodes with a partially depleted absorber (PDA) has been made under front (p-side) and back (n-side) illumination. The photodiode structure consists of an In/sub 0.53/Ga/sub 0.47/As absorption region (450-nm p-InGaAs, 250-nm unintentionally doped InGaAs, and 60-nm n-InGaAs) sandwiched between p- and n-InP layers. For front illumination of a 34-/spl mu/m-diameter photodiode at 2-V bias the saturation currents were 23 and 24 mA at 10 and 1 GHz, respectively. Under similar conditions, backside-illumination resulted in saturation currents of 76 mA (10 GHz) and >160 mA (1 GHz). Backside illumination of a 100-/spl mu/m-diameter photodiode achieved a saturation current >400 mA. For the case of front illumination the device lateral resistance dominates whereas for backside illumination the response is determined primarily by the space charge effect.

Phase performance of an eight-channel wavelength-division-multiplexed analog-delay line

The design of an eight-channel 25 /spl mu/s wavelength-division-multiplexed (WDM) microwave photonic delay line is described. The performance of the delay line was studied by measuring the temperature dependent relative phase drift between channels and the interchannel crosstalk. A simple method for measuring the maximum phase errors produced by the interchannel crosstalk is described and used to measure the maximum error on a channel in this system. The use of polarization interleaving and dispersion compensation to reduce the effects of crosstalk in the system is examined experimentally.

Excess amplitude and excess phase noise of RF photodiodes operated in compression

We present a study of amplitude noise (AN) and residual phase noise (PN) in radio-frequency (RF) photodetectors. Using a heterodyned optical source with a 1-GHz beat frequency, the AN and residual PN spectra of p-i-n photodiodes were measured and found to vary with the level of space-charge-induced RF compression, hereby quantifing the excess AN and PN in the photodetection process.

Minimizing Photodiode Nonlinearities by Compensating Voltage-Dependent Responsivity Effects

Two voltage-dependant responsivity effects, impact ionization and Franz-Keldysh oscillations, are shown to have opposing effects at certain wavelengths in p-i-n photodiodes. It is shown that these two effects can compensate each other and minimize photodiode nonlinearities when optimized with respect to wavelength and bias voltage.

High-saturation-current charge-compensated InGaAs/InP uni-traveling-carrier photodiode

In this paper a high-saturation-current charge-compensated InGaAs/InP uni-traveling-carrier photodiode with charge compensated collector layer is demonstrated. A 16 /spl mu/m diameter photodiode has demonstrated an output current of 80 mA and a bandwidth of 30 GHz.