This paper proposes fiber optic link configurations for use in microwave and millimeter-wave transmission Higher frequencies,such as millimeter-waves, are well suited to transmission of broadband signals. Photodiodes can operate simultaneously as optical detectors and microwave frequency mixers thanks to their inherent nonlinearities. This allows us to increase the output radio frequncy. But, this also generates undesired spurious frequencies, necessitating the use of microwave filters. We discuss here two fiber optic link configurations, i.e., balanced/image canceling photodiode mixing links utilizing the combination of microwave functional components and optical devices to suppress the local/image frequency without filters. These configurations are experimentally investigated at microwave frequencies and local/image frequency suppression is successfully demonstrated.

This paper describes the characteristics and application of lumped double crosstie slow-wave transmission lines (DCT-SLWs) which we previously proposed. Firstly, the relationship between the DCT-SLW's characteristics and their parameters, i. e. triplate stripline widths and inductor resistances, are numerically and experimentally investigated. Excellent slow-wave lines with both high slow-wave factors (1240) and a wide characteristic impedance range (35100Ω) are achieved in good agreement with calculated results. A 50-Ω DCT-SLW that reduces circuit area more than 80%, and has an insertion loss less than that of 22-µm-wide TFMS lines is achieved by adapting a low-loss inductor in the frequencies below 14.5 GHz. Secondly, the application of DCT-SLW to non-dispersive, dispersive delay lines and branch-line hybrids is discussed. Specifically, very small 4-GHz-band branch-line hybrids are fabricated in a chip area of 0.7 mm2. Fundamental microwave circuits utilizing slow-wave lines in MMICs are demonstrated for the first time.

This paper presents a 15-GHz MMIC direct optical injection-locked oscillator (MMIC OILO) with very-wide locking range that uses photosensitive HBTs. The MMIC OILO consists of an HBT and a positive feedback circuit including a Q-damping variable resistor. By utilizing the high-fT/fmax photosensitive HBT, we realize both high-frequency oscillation of 15 GHz and increased equivalent electrical injection power. In addition to increasing the RF injection power, the Q-damping variable resistor effectively reduces the quality-factor of the oscillator, thus realizing the very wide locking range (f) of 567 MHz (f/fosc3.8%). The locking bandwidth of 3.8% is over 10 times wider than that of any yet reported microwave direct OILO. Furthermore, it is shown that the MMIC OILO can also work as a high-gain Q-variable filter photoreceiver by increasing a Q-damping variable resistance over the self-oscillation suppression range.

As a future passive optical network (PON) system, the 10 Gigabit Ethernet PON (10G-EPON) has been standardized in IEEE 802.3av. As conventional Gigabit Ethernet PON (GE-PON) systems have already been widely deployed, 1G/10G co-existence technologies are strongly required for the next system. A gated voltage-controlled-oscillator (G-VCO)-based 10-Gb/s burst-mode clock and data recovery (CDR) circuit is presented for a 1G/10G co-existence PON system. It employs two new circuits to improve jitter transfer and provide tolerance to 1G/10G operation. An injection-controlled jitter-reduction circuit reduces output-clock jitter by 7 dB from 200-MHz input data jitter while keeping a short lock time of 20 ns. A frequency-variation compensation circuit reduces frequency mismatch among the three VCOs on the chip and offers large tolerance to consecutive identical digits. With the compensation, the proposed CDR circuit can employ multi VCOs, which provide tolerance to the 1G/10G co-existence situation. It achieves error-free (bit-error rate < 10-12) operation for 10-G bursts following bursts of other rates, obviously including 1G bursts. It also provides tolerance to a 256-bit sequence without a transition in the data, which is more than enough tolerance for 65-bit CIDs in the 64B/66B code of 10 Gigabit Ethernet.

This paper discusses direct optical injection locking of a millimeter-wave oscillator using an InP/InGaAs heterojunction phototransistor (HPT) and its applications. Previously reported optically injection-locked oscillators (OILOs) are reviewed first. In particular, the features of a direct OILO (DOILO), where synchronization can be achieved by illuminating the active oscillator device itself, are discussed in comparison with the indirect OILO. DOILOs with excellent characteristics require high-performance transistors having both a high maximum oscillation frequency and fast photoresponse. We have developed high-performance opto-microwave-compatible InP/InGaAs HPTs whose layer and fabrication process are fully compatible with ultrahigh-speed heterojunction bipolar transistors. The paper discusses the photocoupling structure, and it is shown that the back-illuminated structure with the aid of InP subcollector enables one to achieve a 100-GHz-class DOILO. The configuration and performance of the 100-GHz-class DOILO are then presented; in particular, injection locking from optical signals with a modulation or beat frequency of around the fundamental (96 GHz) or second harmonic (192 GHz) is successfully demonstrated. To our knowledge, 96 GHz is the highest optically injection-locked frequency and 192 GHz is the highest inputmodulation frequency reported for OILOs. The HPT oscillator IC promises compact, low-power-consumption remote local oscillators for 100-GHz-class wireless systems and 100-Gbit/s-class optoelectronic clock recovery circuits. In addition, when the HPT oscillator is used as a modulator, we can attain cost-effective millimeter-wave systems compatible with conventional optical fiber networks transmitting digitally modulated baseband signals.

This paper proposes three configurations of slow-wave transmission lines for MMICs, i.e., double crosstie slow-wave transmission line (DCT-SLW), meander-like DCT-SLW and lumped DCT-SLW. The DCT-SLW is based on periodic structures and triplate structures. The meander-like DCT-SLW realizes a drastic size reduction in the DCT-SLW using a meander configuration of inductive and capacitive transmission lines. The multilayer spiral inductors are introduced to obtain high impedance characteristics of the meander section. The lumped DCT-SLW achieves a large slow-wave factor of 30. These proposed structures are analytically and experimentally investigated, and excellent performance is obtained. It is also shown that the proposed DCT-SLWs are superior to thin film microstrip (TFMS) lines with the same insertion phase, as regards size.

This paper proposes the laser diode receiving mixer which utilizes the laser diode nonlinearity. The laser diode receiving mixer can make the bidirectional fiber optic link simple and cost-effective. These laser diodes are applied to configure the LD-LD MIX link which consists of two laser diodes, two local oscillators, two microwave switches and one fiber cable. The LD-LD MIX link configuration is extended to introduce novel two fiber optic links, i.e. the local suppression link and the image cancellation link. These links utilize the combination of microwave circuits and optical devices. These configurations are experimentally investigated at microwave frequencies and the QPSK signal transmission is successfully demonstrated.