A highly efficient, diode-pumped, Nd:YAG laser is described. The oscillator utilizes an unstable resonator design with a Gaussian reflectivity output coupler and a side-pumped zigzag slab gain medium. The laser produces 18-mJ, 10-ns pulses at a repetition rate of 242 Hz in a near-TEM00 mode with an optical efficiency of up to 14%. An extended performance test was recently concluded in which the...

We present a novel approach based on machine learning for designing photonic structures. In particular, we focus on strong light confinement that allows the design of an efficient free-space-to-waveguide coupler which is made of Sislab overlying on the top of silica substrate. The learning algorithm is implemented using bitwise square Sicells and the whole optimized device has a footprint of 2μ...

Laser-based metrology has been identified as an enabling technology in the deployment of large, space-borne observatories, where nanometer-level knowledge of fiducial displacement drives overall system performance. In particular, Nd:YAG NPRO (non-planar ring oscillator) based lasers have received considerable attention in this application because of their inherent high coherence at wavelengths ...

We analyze an optical three-port reflection grating by means of a scattering matrix formalism. Amplitude and phase relations among the three ports, i.e., the three orders of diffraction, are derived. Such a grating can be used as an all-reflective, low-loss coupler to Fabry-Perot cavities. We derive the input-output relations of a three-port grating coupled cavity and find distinct properties t...

We demonstrate, for what we believe to be the first time, the use of a 3 x 3 fiber-optic coupler to realize a homodyne optical coherence tomography (OCT) system for en face imaging of highly scattering tissues and turbid media. The homodyne OCT setup exploits the inherent phase shifts between different output ports of a 3 x 3 fiber-optic coupler to extract amplitude information of a sample. Our...

In this paper sensitivity analysis of a wideband backward-wave directional coupler due to fabrication imperfections is done using Monte Carlo method. For using this method, a random stochastic process with Gaussian distribution by 0 average and 0.1 standard deviation is added to the different geometrical parameters of the coupler and the frequency response of the coupler is estimated. The appli...

In this Letter, we propose general optimization methods to design broadband high-efficiency grating couplers for planar waveguides. We attribute the coupling bandwidth to the mismatch of effective indices between the diffracted beam and the actual grating structure around the operation wavelength for fiber to waveguide excitation. The coupling bandwidth formula is deduced. A simple parameter-se...

The performance of a fully optimized optical add/drop multiplexer (OADM), based on null couplers and tilted Bragg gratings, is studied in detail. It is shown that maximization of the device performance involves three main optimization steps. First, the waveguide asymmetry ( 2 1 ratio) should be optimized in order to minimize the extinction ratio of the unwanted mode at the null coupler waist. S...

The manipulation of light propagation is a basic subject in optics and has many important applications. With the development of nano-optics, this area has been downscaled to wavelength or even subwavelength scales. One of the most efficient ways to control light propagation is to exploit interference effects. Here, by manipulating the interference between two nanogrooves on a metal surface, we ...

We have designed a high-efficiency broadband grating coupler for coupling between silicon-on-insulator (SOI) waveguides and optical fibers. The grating is only 13 microm long and 12 microm wide, and the size of the grooves is optimized numerically. For TE polarization the coupling loss to single-mode fiber is below 1 dB over a 35-nm wavelength range when using SOI with a two-pair bottom reflect...