Tunable Optical Add–Drop Multiplexer Based on Silicon Photonic Wire Waveguides

A wavelength tunable optical add–drop multiplexer based on silicon photonic wire waveguides with Bragg-grating-reflectors was demonstrated by tuning the dropping wavelength through thermooptic effect. A 6.6-nm dropping wavelength shift was obtained at a 0.82-W heating power. For the device that is presently polarization-dependent, the 3-dB channel-dropping bandwidth was 0.4 nm and the extinction ratio at the dropping wavelength for port THROUGH was better than 17 dB for assuming 1.6-nm wavelength spacing dense wavelength-division multiplexing. The average tuning speed was about 200$muhboxs$.     

Colorless tunable optical dispersion compensator based on a silica arrayed-waveguide grating and a polymer thermooptic lens

We present a colorless tunable optical dispersion compensator (TODC) comprised of a silica arrayed-waveguide grating (AWG) directly coupled to a polymer thermooptic lens. Using silica for the AWG allows it to be low loss and manufactured by a standard process, and using polymer for the thermooptic lens allows it to have a large tuning range and low electrical power consumption. This hybrid TODC is fully solid-state and scales to a large figure-of-merit (dispersion range times bandwidth squared). We demonstrate a version with 100-GHz free-spectral range and 1300-ps/nm tuning range with a 3-dB bandwidth >39 GHz and a lens power consumption <74 mW.     

Monothically Integrated Long-Wavelength Tunable Photodetector

This paper demonstrated a tunable long-wavelength photodetector by using the heteroepitaxy growth of InP-In_0.53Ga_0.47As-InP p-i-n structure on a GaAs-based GaAs/AlAs Fabry-Perot filter structure. High-quality heteroepitaxy was realized by employing a thin low-temperature buffer layer. A wavelength tuning range of 10.0 nm, an external quantum efficiency of about 23%, a spectral linewidth of 0.8 nm, and a 3-dB bandwidth of 6.2 GHz were simultaneously obtained in the device.     

A Hybrid Electrooptic Microring Resonator-Based $1 times 4times 1$ ROADM for Wafer Scale Optical Interconnects

Pairing high-quality factor $(Q)$ silicon-on-insulator microring resonators with rapidly tunable organic electrooptic claddings has allowed the first demonstration of a silicon-organic hybrid electrooptic reconfigurable optical add/drop multiplexer (ROADM). A coplanar electrode geometry provides up to 0.36 GHz/V of electrooptic voltage tuning for each channel, corresponding to an electrooptic coefficient of $r_{33}=64 hbox{pm/V}$ at wavelengths around 1550 nm. Individual ring resonator devices have 40- $mu{hbox {m}}$ ring radii, 2.7-nm free spectral range, and tuning ranges of 180 GHz. The $1times 4times 1$ ROADM has a footprint of less than 1 ${hbox {mm}}^{2}$ and has been shown to reconfigure in less than a microsecond.      

Single frequency electrooptical tuning of an extended cavity diodelaser at 1500 nm wavelength

A wavelength-tunable, single-frequency GaInAsP-InP laser diode using an intracavity electrooptic LiNbO₃ crystal as the wavelength selective component is discussed. Wavelength tuning is achieved by applying a driving voltage on the crystal electrodes. First results indicate a tuning rate of 1 GHz/V over a tuning range of about 4 nm. This performance was obtained using a nonoptimized X-cut, Z-propagating LiNbO₃ crystal. A potential tuning rate of 6.5 GHz/V is possible with reasonable improvements     

First demonstration of thermally poled electrooptically tunablefiber Bragg gratings

We demonstrate electrooptic tuning of a fiber Bragg grating (FBG) fabricated in a thermally poled fiber. 40 pm of tuning was demonstrated, corresponding to an electrooptic coefficient of 0.25 pm/V. Such electrooptic tunable FBG's have strong potential for numerous devices, including all-fiber amplitude modulators and high-speed tunable filters     

High bit rate and programmable multiwavelength generator based onRaman soliton effect in DSF

A wavelength tunable multiwavelength pulse source with clock rate tunability is described. A tuning range of 32 nm and multiwavelength generation were achieved at a 10 GHz clock rate and a quasi-320 GHz OTDM signal. The device consists of a programmable PLC multiplexer and employs amplitude-to-wavelength conversion based on the Raman soliton effect     

Bragg grating fast tunable filter for wavelength divisionmultiplexing

A Bragg grating fast tunable filter prototype working over a linear tuning range of 45 nm with a maximum tuning speed of 21 nm/ms has been realized. The tunable filter system is based on two piezoelectric stack actuators moving a mechanical device thus compressing an apodized fiber Bragg grating. The filter allows both traction and compression and can work in transmission and in reflection. It is designed to work with a channel spacing of 100 GHz according to the ITU specifications for wavelength division multiplexing systems     

A Tunable Photonic Microwave Filter With a Complex Coefficient Using an Optical RF Phase Shifter

A novel tunable photonic microwave filter with complex coefficients is proposed and experimentally demonstrated. The complex coefficient is generated using a wideband tunable optical RF phase shifter that consists of two electrooptic intensity modulators. The phase of the RF signal is shifted by simply adjusting the bias voltages applied to the two electrooptic intensity modulators, and the phase shift remains constant over the microwave spectral region of interest. A two-tap photonic microwave filter with one tunable complex coefficient, with a wide and continuous tuning range, is experimentally demonstrated.     

Compact Thermally Tunable Silicon Wavelength Switch: Modeling and Characterization

A wavelength-selective photonic switch is developed based on a Si microring resonator using thermooptic effect. The 10-mum-diameter microring resonator uses single-mode strip Si waveguides of dimension 0.25 mum times 0.45 mum operating at 1.5 mum. Full-width at half-maximum are in the range 0.1-0.2 nm. The ultrawide tunable range (>6.4 nm) and wide free spectral range (~18 nm) of the switch element enables wavelength reconflgurable multichannel matrix switch by wavelength multiplexing/demultiplexing. Average rise delay time of 14 mus with low switching power of 3.15 mW has been achieved with 0.2-nm wavelength tuning and 78 mus, 104 mW for 6.4-nm tuning. Fall delay times are usually less than 10 mus. Thermal simulations show 10%-20% agreement with the measurements up to 3.2-nm tuning. The compact size of the switch shows its potential as an active element in photonic integrated circuits.     

Tunable Photodetector Based on GaAs/InP Wafer Bonding

We demonstrate a tunable long wavelength vertical-cavity photodetector which is fabricated by bonding a GaAs-based tunable filter with an InP-based absorption structure. The wavelength tuning range of 10.5 nm was achieved via thermal-optic effect. The external quantum efficiency of about 22%, the spectral linewidth as narrow as 0.6 nm, and the 3-dB bandwidth of 12 GHz were obtained in the device.     

Broadly wavelength-tunable external cavity, mid-infrared quantumcascade lasers

Wavelength tuning over 120 nm for a grating-coupled 5.1-μm quantum-cascade type-I laser was studied for temperature from 80 to 243 K (-30°C). Both the Littman-Metcalf and first-order grating direct feedback cavity configurations were used with similar tuning results. The goal is to achieve broad tunability, and the result is a combined grating and temperature tuning of 245 nm, from 5.040 to 5.285 μm. The laser was designed for predominantly single-mode or at most, two-longitudinal mode operation. The instrument-limited laser linewidth was less than the cavity longitudinal mode spacing. Stepping-motor control of the grating allowed 0.4-GHz wavelength increments (35 pm) to be realized with high reproducibility. A current-induced wavelength shift of ~2-3 GHz was observed, corresponding to an effective refractive index change of ~10^-3. Analysis indicates that single-mode, continuously tunable operation is feasible with a more optimal device and cavity     

Tunable Mach-Zehnder polarization splitter using height-tapered Y-branches

A tunable TE/TM polarization splitter, based on a Mach-Zehnder interferometer with an electrooptic switch, is demonstrated in GaAs-AlGaAs. Symmetric and asymmetric Y-branches employing height-tapered waveguides are used to achieve power splitting and mode sorting, respectively, in the interferometer. The device has an extinction ratio of /spl sim/20 dB and an excess loss less than 1.5 dB for both TE and TM polarized light. The device can be reconfigured by tuning the switching voltage for operation at both 1.3- and 1.55-pm wavelengths.     

Sampled grating tunable twin-guide laser diodes with over 40-nm electronic tuning range

Device and tuning characteristics of sampled grating tunable twin-guide laser diodes are presented. The vertically integrated, monolithic widely tunable laser requires only two tuning currents to fully cover a wavelength range of more than 40 nm by electrooptic tuning. Its tuning behavior is quasi-continuous with up to 8.2-nm broad continuous tuning regions. High sidemode suppression (SMSR /spl ges/ 35 dB) as well as large output power (P /spl ges/ 10 mW) are obtained over the wavelength range from 1520.5 to 1561.5 nm.     

Low-voltage tunable TE/TM converter on ion-sliced lithium niobate thin film

Lift-off of a prefabricated thin-film lithium niobate device using ion slicing has been demonstrated. The device is a low-voltage electro-optically tunable TE/TM mode converter, which is fabricated on a sliced 10 /spl mu/m-thick film. A new electrode configuration allows this thin-film device low-voltage tuning of the mode conversion wavelength at 0.26 nm/V. The high tuning per volt is attributed to an improved overlap integral in the thin-film form of the device.     

Tunable dual-mode operation in a chirped gratingdistributed-feedback laser

We report on the tunable dual-mode operation of a chirped grating distributed-feedback (DFB) laser device with two integrated modulators which act as tuning sections. A transfer-matrix model is used to simulate the amplified spontaneous emission spectrum for a chirped grating DFB laser. Several types of dual-mode operation are observed for wavelength spacings of 0.5 nm and 1.4 nm corresponding to frequency detunings of 63 GHz and 175 GHz     

Widely tunable chaotic fiber laser for WDM-PON detection

A widely tunable high precision chaotic fiber laser is proposed and experimentally demonstrated. A tunable fiber Bragg grating （TFBG） filter is used as a tuning element to determine the turning range from 1533 nm to 1558 nm with a linewidth of 0.5 nm at any wavelength. The wide tuning range is capable of supporting 32 wavelength-division mul- tiplexing （WDM） channels with 100 GHz channel spacing. All single wavelengths are found to be chaotic with 10 GHz bandwidth. The full width at half maximum （FWHM） of the chaotic correlation curve of the different wave- lengths is on a picosecond time scale, thereby offering millimeter spatial resolution in WDM detection.     

Versatile integrated PMD emulation and compensation elements

Highly versatile building blocks for polarization-mode dispersion (PMD) emulation and compensation are demonstrated using tunable all-pass filters fabricated in 4%-index-contrast planar waveguides. While the all-pass filters can approximate any phase response, the complexity in setting the individual filter parameters is minimized by restricting the all-pass filter responses to realize a range of differential delays, dispersion, and dispersion slope. A single section can approximate first-order or a higher-order PMD term or emulate chromatic or higher-order dispersion. A differential group delay (DGD) tuning range over 100 ps is demonstrated for 10 Gb/s and 25 ps for 40 Gb/s data. Second-order PMD with a tuning range of 255 ps/sup 2/ and third-order PMD with a range of 2430 ps/sup 3/ are also demonstrated. The larger index contrast required for the ring-resonator-based all-pass filters is advantageous in reducing the thermooptic response time to achieve polarization rotation speeds on the order of 0.1 /spl mu/s/degree. The device is interferometrically stable and compact in size. It can be fully integrated, scaled to many sections, and can implement a variety of PMD synthesis and statistical-emulation approaches.     

Widely tunable Ce- and Er-codoped fluorozirconate fiber laser with 975-nm laser diode pumping

A spectrally narrowed widely tunable Ce/sup 3+/: Er/sup 3+/-codoped fluorozirconate (ZBLAN) fiber laser with a continuous-wave laser diode pumping at 975-nm pumping is demonstrated. Wide tunable range over 120 nm (1490-1610 nm) is attained by using a diffraction grating combined with a tuning mirror in the Ce/sup 3+/: Er/sup 3+/-ZBLAN fiber laser cavity. Rate-equation model analysis shows that the tunable range can expand further by using a wavelength-dependent reflectivity cavity mirror.     

基于低温缓冲层的单片集成长波长可调谐光探测器

实现了一种单片集成的长波长可调谐光探测器.通过外延实验,摸索出低温缓冲层的最佳生长条件,成功地在GaAs衬底上生长出晶格失配度约4%的高质量的InP基材料.基于此低温缓冲层,在GaAs衬底上首先生长GaAs/AlAs材料的F-P腔滤波器,然后异质外延InP-In0.53 Ga0.47 As-InP材料的PIN结构.制作出的器件通过热调谐,峰值波长从1533.1nm红移到1543.1nm,实现了10.0nm的调谐范围,同时响应线宽维持在0.8nm以下,量子效率保持在23%以上,响应速率达到6.2GHz.