We report on the experimental observation of reduced light energy transport and disorderinduced localization close to a boundary of a truncated one-dimensional (1D) disordered photonic lattice. Our observations uncover that near the boundary a higher level of disorder is required to obtain similar localization than in the bulk.OCIS codes: 130.2790, 240.6690 Light and particle dynamics in disordered media is a topic of continuously renewed interest. In solid-state physics, particles scattered by lattice defects generate a random walk, resulting in a transition from ballistic transport to complete suppression of transport when disorder exceeds certain level [1]. Due to this transition, the infinitely extended eigenmodes of the system are transformed into localized modes [2]. This is a universal concept applicable to a variety of physical settings [3,4]. Optical setups proved to be promising candidates to observe localization in random media [5][6][7][8][9][10] due to analogy of a solid and photonic lattice, where longitudinally invariant disorder can be realized [11,12]. Since the localization relies on fluctuations imposed on otherwise periodic structure, a truncation of a disordered lattice yields distortions of the underlying periodicity, which may have a strong impact on wave localization.In this Letter we observe wave-packet localization at the edge of disordered truncated 1D lattices for sufficiently large levels of disorder. A higher degree of disorder (as compared to disorder required for localization in the lattice center) is required to achieve the same degree of localization at the surface of the lattice, which we attribute to a repulsive potential arising in the vicinity of the boundary [13].

Applications in life sciences and information technology require all-optical solutions. In the inevitable race towards miniaturized optical circuits, all-integrated solutions will prevail against bulk setups. Because of its outstanding nonlinear properties, lithium niobate (LiNbO3) emerged as the key platform for integrated optics. In this paper, we discuss the direct femtosecond (fs) laser inscription technique whose flexibility enables the realization of two- and three-dimensional embedded optical waveguides in various optical materials. Linear and nonlinear components for monolithic and hybrid waveguide devices are characterized and their perspectives are reviewed, e.g. couplers, Bragg reflectors, frequency converters, amplitude modulators and gain modules. Finally, we demonstrate a monolithic LiNbO3 waveguide chip that combines a frequency doubling and a modulating unit. Thumbnail image of Schematic of a hybrid fs laser written chip that comprises a rare-earth-doped laser section (a), a frequency doubling unit (b), Bragg reflectors (c), waveguide splitters (d) and an amplitude modulator (e)

A continuous-wave singly-resonant optical parametric oscillator (SRO) with an optimum extraction efficiency, that can be adjusted independent of the pump power, is demonstrated. The scheme employs a variable-reflectivity volume Bragg grating (VBG) as the output coupler of a ring cavity, omitting any additional intra-cavity elements. In this configuration, we obtained a 75%-efficient SRO with a combined signal (19 W @ 1.55 µm) and idler (11 W @ 3.4 µm) output power of 30 W.

Femto-second laser writing was used to fabricate waveguides in a z-cut KTP sample with losses below 0.8 dB/cm. They were used for efficient, broad bandwidth, Type II birefringent second harmonic generation to the green. The temperature and wavelength bandwidth were, 28 C ∙ cm and 0.85 nm ∙ cm, respectively.

A numerical model for amplification of ultrashort pulses with high repetition rates in fiber amplifiers is presented. The pulse propagation is modeled by jointly solving the steady-state rate equations and the generalized nonlinear Schrödinger equation, which allows accurate treatment of nonlinear and dispersive effects whilst considering arbitrary spatial and spectral gain dependencies. Comparison of data acquired by using the developed model and experimental results prove to be in good agreement.