Vitaly Rymanov

Millimeter-Wave Photonic Components for Broadband Wireless Systems

We report on advanced millimeter-wave (mm-wave) photonic components for broadband radio transmission. We have developed self-pulsating 60-GHz range quantum-dash Fabry-Perot mode-locked laser diodes (MLLD) for passive, i.e., unlocked, photonic mm-wave generation with comparably low-phase noise level of -76 dBc/Hz @ 100-kHz offset from a 58.8-GHz carrier. We further report on high-frequency 1.55-μm waveguide photodiodes (PD) with partially p-doped absorber for broadband operation (f3dB ~70-110 GHz) and peak output power levels up to +4.5 dBm @ 110 GHz as well as wideband antenna integrated photomixers for operation within 30-300 GHz and peak output power levels of -11 dBm @ 100 GHz and 6-mA photocurrent. We further present compact 60-GHz wireless transmitter and receiver modules for wireless transmission of uncompressed 1080p (2.97 Gb/s) HDTV signals utilizing the developed MLLD and mm-wave PD. Error-free (BER = 10-9, 231 - 1 PRBS, NRZ) outdoor wireless transmission of 3 Gb/s over 25 m is demonstrated, as well as wireless transmission of uncompressed HDTV signals in the 60-GHz band. Finally, an advanced 60-GHz photonic wireless system offering record data throughputs and spectral efficiencies is presented. For the first time, we demonstrate photonic wireless transmission of data throughputs up to 27.04 Gb/s (EVM 17.6%) using a 16-QAM OFDM modulation format resulting in a spectral efficiency as high as 3.86 b/s/Hz. Wireless experiments were carried out within the regulated 57-64-GHz band in a lab environment with a maximum transmit power of - 1 dBm and 23 dBi gain antennas for a wireless span of 2.5 m. This span can be extended to some 100 m when using high-gain antennas and higher transmit power levels.

Triple transit region photodiodes (TTR-PDs) providing high millimeter wave output power

We report on a novel triple transit region (TTR) layer structure for 1.55 μm waveguide photodiodes (PDs) providing high output power in the millimeter wave (mmW) regime. Basically, the TTR-PD layer structure consists of three transit layers, in which electrons drift at saturation velocity or even at overshoot velocity. Sufficiently strong electric fields (>3000 V/cm) are achieved in all three transit layers even in the undepleted absorber layer and even at very high optical input power levels. This is achieved by incorporating three 10 nm thick p-doped electric field clamp layers. Numerical simulations using the drift-diffusion model (DDM) indicate that for optical intensities up to ~500 kW/cm(2), no saturation effects occur, i.e. the electric field exceeds the critical electric field in all three transit layers. This fact in conjunction with a high-frequency double-mushroom cross-section of the waveguide TTR-PD ensures high output power levels at mmW frequencies. Fabricated 1.55 µm InGaAs(P)/InP waveguide TTR-PDs exhibit output power levels exceeding 0 dBm (1 mW) and a return loss (RL) up to ~24 dB. Broadband operation with a 3 dB bandwidth beyond 110 GHz is achieved.

Thermopile antennas for detection of millimeter waves

A thermopile structure is proposed for the detection of microwave/millimeter wave radiation. The thermopairs in the suggested linear arrangement function as antennas. 5.58 V/W responsivity was achieved at 100 GHz with 40 serial connected thermopairs. The experimentally observed polarity and frequency dependence convincingly verify the proper detector operation.

60GHz radio-over-fibre wireless system for bridging 10Gb/s ethernet links

We present a 60 GHz radio-over-fibre system for broadband wireless transmission up to 12.5 Gb/s sufficient for bridging 10 Gb/s Ethernet links. The potential for km-range wireless transmission is further discussed.

Robust 71–76 GHz radio-over-fiber wireless link with high-dynamic range photonic assisted transmitter and laser phase-noise insensitive SBD receiver

This paper describes a robust radio-over-fiber wireless link system for use in wireless extension and mobile backhaul applications. The wireless link operates at 71-75 GHz E-band carrier frequencies and can transmit ultra-high access data such as Gigabit Ethernet or OC-48 up to 2.5 Gbps. Enabling photonic technologies, system configurations, and lab trials are presented.

Optoelectronic

We propose and demonstrate a K -band optoelectronic oscillator with ultralow phase noise performance and a frequency tuning range exceeding 1 GHz. The operation principle is based upon using two parallel optoelectronic loops with similar but not equal length and an electrical phase shifter for frequency tuning. We experimentally demonstrate tunable microwave signal generation within 20.7-21.8 GHz with a coarse frequency resolution of ~100 MHz. Fine tuning of the generated signal within a range of ±5 MHz is also achieved. The linewidth and phase noise of the generated microwave signal are <;3 Hz and -105 dBc/Hz at 10-kHz offset, respectively. Within the full gigahertz tuning range, the phase noise and output power of the generated microwave signal varies by only ±1.5 and <;1 dB, respectively.

K

Here, we present a compact photonic transmitter module featuring an integrated InP-based 1.55 μm triple transit region photodiode (TTR-PD) chip and a WR-12 rectangular waveguide output for E-band (60-90 GHz) radio-over-fiber applications. In order to enable work capability in broadband wireless E-band communications over long- and medium-range distances, the fabricated TTR-PD module provides excellent frequency flatness exhibiting a maximum deviation of ±1 dB within the complete 71-86 GHz band and high-power levels in excess of -5 dBm (without external amplification) at a photocurrent of 10 mA. In addition, we report for the first time on non-isothermal analyses of TTR-PDs using the drift-diffusion model with integrated Joule heat generation.

-Band Oscillator With Gigahertz Tuning Range and Low Phase Noise

High data rate photonic wireless systems operating at millimeter wave carrier frequencies are considered as a disruptive technology e.g. for reach extension in optical access networks and for mobile backhauling. Recently, we demonstrated 60 GHz photonic wireless systems with record data rates up to 27 Gbit/s. Because of the oxygen absorption at 60 GHz, it is beneficial for fixed wireless systems with spans exceeding 1 km to operate at even higher frequencies. Here, the recently regulated 10 GHz bandwidth within the E-band (60-90 GHz) is of particular interest, covering the 71-76 GHz and 81-86 GHz allocations for multi-gigabit wireless transmission. For this purpose, wideband waveguide photodetectors with high external quantum efficiency are required. Here, we report on double mushroom 1.55 μm waveguide photodetectors for integration in an E-band wireless transmitter module. The developed photodetector consists of a partially p-doped, partly non-intentionally doped absorbing layer centered in a mushroom-type optical waveguide, overcoming the compromise between the junction capacitance and the series resistance. For efficient fiber-chip coupling, a second mushroom-type passive optical waveguide is used. In contrast to the conventional shallow ridge waveguide approach, the mushroom-type passive waveguide allows to shift the center of the optical mode further away from the top surface, thus reducing waveguide losses due to the surface roughness. Experimentally, a very flat frequency response with a deviation up to ±1 dB in the entire E-band has been found together with an output power level of -15.7 dBm at 10 mA photocurrent and at a frequency of 73 GHz.

Compact triple transit region photodiode module with WR-12 rectangular waveguide output

An integrated 110 GHz coherent photonic mixer (CPX) is designed and fabricated for coherent RoF (CRoF) mobile backhaul links. The CPX simultaneously performs optical WDM channel selection and direct optical-to-RF conversion. Due to its broadband performance, the CPX simultaneously supports future wireless systems operating in the 57-64 GHz, 71-76 GHz, 81-86 GHz bands and even research-type W-band systems. The RF frequency response of the CPX in the 60 GHz and 70/80 GHz bands is about 4 dB higher as compared to a commercial 110 GHz photodiode. A CRoF experiment is carried out to also prove the advantageous performance of the new 110 GHz CPX against a commercially available 110 GHz photodiode in a CRoF system experiment with a 25 km standard single-mode fiber (SMF) and a 40 m long 71-76 GHz wireless link. This experiment reveals a significant improvement in optical receiver sensitivity of the radio access unit (RAU) with a required optical signal power as low as -32 dBm at a BER=2×10-3 for a 1 Gbit/s NRZ-OOK data signal.

Double mushroom 1.55-μm waveguide photodetectors for integrated E-band (60-90 GHz) wireless transmitter modules

Microwave photonics can provide superior advantages towards ultra-wideband wireless communications. In this work, we present an integration platform for 72GHz photodiode based wireless transmitter. The placement and positioning of discrete LNA and PA components, the bias-tee design parameters of photodiode, LNA and PA, and the design parameters for low-loss transition from CPW output of amplified electrical signal at the output of PA to E-band WR12 rectangular waveguide have to be carefully determined. We present general design principles of 72GHz photodiode integration platform. Further, we compare different substrates, which have been implemented into the platform, based on numerical results.