Rajiv Iyer

Enhanced second-harmonic generation in AlGaAs microring resonators

Highly efficient second-harmonic generation can be achieved by harnessing resonance effects in microring resonator structures. We propose an angular quasi-phase-matching scheme based on the position dependence of polarization inside the ring resonator.

Exact dynamic localization in curved AlGaAs optical waveguide arrays.

We present experimental observations of exact dynamic localization of an optical beam in a periodically curved AlGaAs waveguide array. The dynamic localization of the beam is “exact” in that it is observed even when the photonic band of the array is not well described in the nearest-neighbor tight-binding approximation. We present the spatial evolution of the beam around the two-period plane in the structure, explicitly demonstrating the delocalization and subsequent relocalization of the beam. We also demonstrate the strong wavelength dependence of the beam relocalization for a four period structure.

Telecom-Band Directional Coupler Written With Femtosecond Fiber Laser

A femtosecond fiber laser with 1-MHz repetition rate was optimized to write low-loss waveguides and directional couplers inside bulk borosilicate glass. For the first time, this three-dimensional writing method has produced low insertion loss and near-unity maximum coupling ratio. Results are presented at telecommunication wavelengths of 1310 and 1550 nm

Raman gain from waveguides inscribed in KGd(WO4)2 by high repetition rate femtosecond laser

We report the formation of waveguides in Raman-active KGd(WO4)2 with a focused, high repetition rate femtosecond laser. Parallel guiding regions, formed to either side of the laser-induced damage track, supported TE and TM modes that coupled efficiently to optical fiber at telecom wavelengths. Micro-Raman spectroscopy of the guiding regions revealed the preservation of the characteristic 768 and 901cm−1 Raman mode intensities. Raman gain with 6% efficiency was demonstrated for the 768cm−1 Raman line by pumping the waveguide with an infrared 80ps source, the first time Raman gain has been reported in laser formed waveguides.

Switchable AlxGa1−xAs all-optical delay line at 1.55μm

The authors demonstrate an on-chip optical delay in AlxGa1−xAs that operates at room temperature and 1.55μm. A nonlinear directional coupler for optical switching and a 188ps long racetrack structure provide bit delays of >100 for picosecond pulses. In the linear regime the transmission ratio of the slow channel is 74%, which reduces to 40% with increasing peak intensity. (Meanwhile, the fast channel output increases from 26% to 60%.) Switching occurs due to a nonlinear detuning of the directional coupler, limited by three-photon absorption and time-averaging effects. This proof-of-principle device can operate at up to 5GHz and is promising for optical buffering applications.

Exact dynamic localization in curved AlGaAs optical waveguide arrays

We present the first experimental observations of exact dynamic localization of an optical beam in periodically-curved strongly-coupled waveguide arrays. Spatial and spectral measurements of two and four period devices agree well with theory.

Switchable All-Optical 188-ps Delay Line in AlGaAs

An integrated AlGaAs all-optical 188-ps delay line is characterized over the C- and L- bands. Self-switching by input intensity is achieved using a nonlinear directional coupler and a racetrack delay line.

Integrated high order filters in AlGaAs waveguides with up to eight side-coupled racetrack microresonators

Side-coupled-integrated-spaced-sequence-of-resonators (SCISSORs) with many rings are important for controlling the behavior of light propagation. We show the linear performance of SCISSORs in high index-contrast AlGaAs in 1, 2, 4, and 8 ring configurations.

Broadband control of exact dynamic localization bandwidth in curved, strongly coupled optical waveguide arrays

We present the first experimental observation of exact dynamic localization in waveguide arrays with non-square-wave curvatures. The deviated square-wave profile offers broadband control over the bandwidth of the dynamic localization.

Dynamic localization in curved coupled optical waveguide arrays

We present the experimental observation of three different optical localization schemes in curved coupled optical waveguide arrays. Exact and approximate dynamic localization are compared and a new type of localization, quasi-Bloch oscillations, is demonstrated.