Building a more versatile laser

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. ( — One of the drawbacks associated with using semiconductor lasers is that many of them can only produce a beam of a single wavelength, and can only send that beam in one direction at a time. There have been efforts to tune lasers so that different wavelengths can be achieved, but these lasers still emit light only in one direction, and one wavelength at a given time. All that could change, though. Harvard University scientists Federico Capasso and Nanfang Yu , in Cambridge, Massachusetts, have been working with an international team to develop a laser that offers multibeam emission. Citation: Building a more versatile laser (2009, November 16) retrieved 18 August 2019 from Scientists demonstrate highly directional semiconductor lasers The special grating directs laser beams. Illustration by Nanfang Yu, simulation results from the computer modeling and 3D illustration software. Explore further “Usually semiconductor lasers can only emit a single wavelength. Our design, though, allows us to emit beams in different directions, as well as beams of different wavelengths,” Capasso tells Capasso believes that this work with fellow scientists at Harvard, and from the Institute of Quantum Electronics in Zurich, Switzerland, as well as Hamamatsu Photonics K.K. in Hamamatsu, Japan, will lead to a number of uses in a variety of applications in the future. He refers to the group’s efforts as “beam engineering.” The results of the latest simulations and experiments the group has done with multibeam lasers can be seen in Applied Physics Letters: “Multi-beam multi-wavelength semiconductor lasers.”The secret to the success of these lasers, Capasso explains, is the specially designed collimator used to direct the beams. “We realized that by designing a special collimator with two different gratings, we could create a beam that comes out to you at a certain angle, and another beam that comes out at a different angle. This essential allows us to use diffraction and interference to design beams to our specifications.”Previously, Capasso and his peers had shown how a plasmonic structure with aperture grating on a laser facet could collimate the beam that emerged. Taking this principle, the international team decided to split the beam of a quantum cascade laser into two different beams by using successive plasmonic gratings to define different lengths and periods on the laser’s facet. The result was that it was possible to create two different beams – of different wavelengths and heading in different directions – with the same laser.“We have created a multi-functional laser,” Capasso insists, “that has a lot of potential. Not only can this add to the functionality of lasers as we have them already, but there is also the possibility of new applications in the future. This beam engineering will make lasers more efficient, since it requires more focus on designing the facet, rather than having to build an entire laser for each application.” Some of the possible applications include fiber optic communications, interferometry, spectroscopy, holography, and LiDAR (light detection and ranging).Capasso hopes that this work can be continued in the future. “We want to be able to steer the beam in real time, rather than having to set it ahead of time. Real time beam steering has been done by using multiple lasers in complicated maneuvers, but we hope to be able to use beam engineering to do it with a single laser.”More information: Nanfang Yu, et. al., “Multi-beam multi-wavelength semiconductor lasers,” Applied Physics Letters (2009). Available online: Copyright 2009 All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of read more

The other side of Ghalib

first_img‘Mirza Ghalib portrayed on the stage a number of times but never in a negative avatar. And that is the basic premise of my play, said Aziz Qurashi. Generally, people tend to go gaga at the mere mention of the Urdu poet. But few are aware that he had a negative side to him as well.  Qurashi, in his play Aitraaf-e-ghalib (which means confessions of Ghalib),  explores facets of him which are either unknown to many or simply kept under wraps for fear of disgrace. Also Read – ‘Playing Jojo was emotionally exhausting’‘The plot of the play revolves around Ghalib in the last stages of his life and as he lay on his death bed, how the poet ruminated about his past deeds and mistakes which he now knows can never be reversed’ said Qurashi.Ghalib is portrayed as a split personality on the stage whereby there are three Ghalibs. One portrays the role a nawab, the second a poet and the third old Ghalib.The highlight of the play is a dialogue between the two Ghalibs (Nawab and poet) and how each one questions the other’s existence and tries to explore who is more imperative for survival and fame. Also Read – Leslie doing new comedy special with Netflix‘Like the Nawab Ghalib points out that if he was not born in a aristocratic family, then the poet Ghalib would have never been honed. Similarly, the poet Ghalib says that if he never tried his hand at poetry, then no one would have cared for Nawab’s aristocracy,’ added Qurashi.Aitraaf-e-Ghalib is a musical based on flashbacks. ‘Ghalib indulged in all sorts of vices. He used to go to prostitutes, was an alcoholic but at the same time was a genius,’ said Qurashi. One of the most striking facts about Ghalib’s life was that he never mentioned his wife or children. Nor was there any narration about his family life. But he used to visit a brothel where his mistress used to sing his couplets as songs and entertain people during those days.With a cast and crew of over 35 people, the play has been recreated using 80 per cent of Ghalib’s original letters. ‘With a view to get as real as possible, the same atmosphere in terms of costumes, props and lighting has been recreated on the stage,’ said Qurashi.DETAILAt: Stein Auditorium, India Habitat Centre, Lodi Road When: 30 December Timings: 7 pm onwardslast_img read more

BJP spending money to publish fake news Mamata

first_imgKolkata: Coming down heavily on the opposition, Chief Minister Mamata Banerjee on Wednesday said that an unholy nexus has been formed that is misinforming people in connivance with a vernacular daily.Elaborating on the ongoing trouble and violence before the forthcoming Panchayat polls, she said problems have arisen in namely seven districts. In Mohammadbazar, the BJP had brought in people from Jharkhand. In Bankura, veteran CPI(M) leader Basudeb Acharya was injured. In Sandeshkhali, a Trinamool Congress worker was killed while in Sashan in North 24-Parganas, a party leader was murdered on Wednesday evening. In Murshidabad, there were incidents of violence and in Birbhum’s Nalhati, a vernacular daily had created a hype, trying to influence people. In South Dinajpur, veteran party leader Asim Ghosh’s house was ransacked by unidentified miscreants. Also Read – Heavy rain hits traffic, flights”I generally do not take the name of the newspaper but it is Anandabazar that is circulating false stories. If we recall, before 2016 Assembly polls, the newspaper had written against the TMC and projected an alliance. Now, it is writing stories in such a manner as if there is violence throughout the state and such stories are being circulated to mislead the masses.”The Chief Minister said no incidents of violence were reported from East and West Burdwan, North Dinajpur, Cooch Behar, Malda and Nadia. She alleged that the BJP was trying to mislead people and are “spending money to publish false news just to create hype. I do not know whether it is BJP’s paid news or not.” Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedShe further added: “If any incident takes place, one vernacular television channel circulates the news throughout the day just to influence the commoners.”She also wondered that if violence had erupted in the whole of Bengal, then how could the opposition file nearly 70,000 candidates and “if you take the number of Independent candidates, it amounts to somewhere around 90,000.”Banerjee stated: “How could we forget those days when our supporters were killed by the CPI(M) cadres in Netai, Singur and Nandigram. They chopped off the hands of our supporters in Howrah. Our candidates were prevented from filing nominations in the Panchayat elections. In 2003, we had filed 30,000 candidates followed by 35,000 candidates in 2008.” Banerjee maintained that the opposition does not have the strength to file candidates in all the seats. “They fail to get candidates. It is not our fault. I cannot go to their houses to cook food,” she said.She alleged that the BJP, CPI(M) and Congress are working hand-in-glove in the Panchayat elections. She also said many CPI(M) backed goons have become candidates for the BJP. “It’s a real shame. The party has failed to strengthen its organisation and now the goons are working for a communal party like the BJP.” She said in Delhi, the Congress is against the saffron party and here in Bengal, they are working with it. We don’t believe in such a principle. We are against the communal BJP in Bengal and in Delhi as well.”Banerjee added that there will not be any bandh called by the Left Front on April 13. “It’s another gimmick. It is a six-hour bandh from 6 am to 12 noon. Most of the shops are opened after 10 am. People come to the office around 11 am.” She said the buses and vehicles will ply as usual and the offices will remain open too.Speaking on the assault of a journalist, she said no police complaint was made. “It is a tragedy that before going to the administration to register a complaint, they have lodged one with a local vernacular daily and made a huge noise to attract the attention of the people.”last_img read more

IAS cadre sees reshuffle

first_imgKolkata: In a reshuffle in the IAS cadre in Bengal, Dr Preeti Goyal has become the Additional District Magistrate (ADM) of North 24-Parganas.An IAS of 2013 batch, Dr Goyal, who is a medical practitioner, was earlier posted as Sub-Divisional Officer (SDO) Arambagh. She had fought against illegal sand mining as SDO Arambagh and brought an end to the menace in the area. Dr Goyal had also united a 65-year-old woman with her near and dear ones after five decades, after finding out her native place in Nagaland. Also Read – Heavy rain hits traffic, flightsNitin Singhania of the same batch has become the Joint Secretary in Chief Minister’s Office (CMO). He was earlier posted as SDO Kalna. Abhishek Kumar Tiwary, who was Joint Secretary in CMO, has been made ADM Howrah. Dr Rajat Nanda, who was SDO Serampore, has become ADM Hooghly and Nidhi, who is also of the 2013 batch, has become ADM Nadia. Anshul Gupta has become ADM Murshidabad. He was earlier posted as SDO Uluberia.Tshering Y Bhutia, who was SDO Islampur, has become ADM Jalpaiguri. Manish Mihra is the new SDO Islampur. Raju Mishra, who was Officer on Special Duty (OSD) in Higher Education department, has become SDO Khatra. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedDr Akanksha Bhaskar, OSD of Health and Family Welfare, has become ADO Raghunathpur. Tushar Singhla, OSD of Power department, has become SDO Uluberia.Smrutiranjan Mohanty of 2015 batch has become SDO Rampurhat. He was earlier posted as OSD School Education. Lakshmi B Tanneeru, OSD of the Women and Child Development and Social Welfare department, has become SDO Arambagh.Shevale Abhijit Tukaram has become SDO Kalimpong. Kuhuk Bhushan, who was OSD Finance, has become SDO Haldia. Dhivya L, who was an OSD in Personnel and Administrative Reforms and e-governance department, has become SDO Domkal. Srikanth Palli has been posted as SDO Durgapur.last_img read more

Blend your summer clothes with winter

first_imgFalling short of winter wear and have an office party to attend? A great mix of summer and winter wear can ease your dressing woes in the winter season.Here are five ways to glamourise your summer outfit for the winter season:Floral summer dress: A cute floral summer dress can go great lengths when paired with the right accessories. Heels can glamorise any outfit, so team your favourite pair of black pumps with your summer dress. Another way of turning a summer dress into a party outfit is by slapping on a black blazer and head to your office party in style. Also Read – Add new books to your shelfPlain sheath dress: Do you have any plain dress in your wardrobe? It could be a plain black shirt dress or a plain dress in any colour. You can add glamour to this by either sporting a sequined clutch and high gladiator heels or mules. This look is sporty, chic yet glamorous.A logo shirt: Who would’ve thought wearing a simple logo shirt can make a fun party outfit? Pair the logo t-shirt with a high waist leather skirt. This look is grungey and can make a perfect festive outfit when completed with a pair of black pumps. A pair of studded earrings adds that extra bit of oomph.Playsuits: Playsuits are another great option to turn into party wear. Pull out any solid colored playsuit as they’re flirty and fun, just about perfect for any night out. They’re comfortable yet glamorous and look great the way they are. Pair heels along chunky bracelets and earrings to go with them.last_img read more

A convoluted heist drama

first_img“Den of Thieves” is a convolutedly narrated heist film that involves concepts from other superior crime thrillers of the past. With a handful of stylish shootouts, chase sequences and other confrontations bridged together by a lacklustre screenplay, this over-the-top crime saga is a predictable derivative saga of cops and robbers.The film begins with some onscreen graphics informing us about some true-life statistics about bank robberies in the US. Apparently, a bank robbery occurs every 48 minutes there. Given this information, one expects that the opening sequence in Los Angeles would give us an adrenaline-packed thrilling insight into one such robbery. But instead, we witness a run-of-the-mill heist of an armoured truck by a very well armed gang of thieves. Also Read – Add new books to your shelfThis dacoity is led by Ray Merriman (Pablo Schreiber) a one-time special forces soldier and criminal mastermind and cohorts including Enson (Curtis “50 Cents Jackson) and Bosco (Evan Jones).Despite the robbers’ military precision, there are fatalities on both sides. And to the amusement of his colleagues, Ray mentions, “We are cop killers now.”The case catches the attention of the Major Crimes unit of the local Sheriff’s department, led by Nick Flanagan (Gerard Butler) who is also known as “Big Nick” among his co-workers. While surveying the scene of the crime, we learn that he is at loggerheads with the head of FBI. At the same time, he is wary and anxious as he gravely says, “We’re dealing with a different animal here, boys.” Also Read – Over 2 hours screen time daily will make your kids impulsiveTo top it all, Nick has a troubled personal life. He tells us that he and his unit are bad guys and there’s no reason to doubt that claim.The battle of wills between Ray and Nick aspires an epic level, but the characters exhibit far less real respect for one another. The bad blood incorporates a personal element where both Ray and Nick casually indulge in sex with the same person.Personal foibles apart, Ray and his team eye the Los Angeles branch of the Federal Reserve. In order to succeed in their endeavour, they rope in a genial bartender Donnie (O’Shea Jackson Jr) who is skilled in speed racing. But Nick who tries to stay a step ahead of Ray, roughs up Donnie who knows the consequences of turning into an informer.The plot takes a convoluted route. It oscillates back and forth between the two sides, offering would-be poignant exchanges. It teases the audience unnecessarily with personal issues and wastes precious time that could have been spent on the tense heist and its explosive aftermath, which is where the viewer wants to be. The execution in these moments is thrilling, although muddied by a final plot twist. There is not much time spent on motives or on explaining the ridiculous twist at the end. Also, parts of the film remind you of scenes in “The Usual Suspects” and the 1995 released film “Heat”.As for the performances, despite packed with testosterone-fuelled swagger and tough guy posturing by its ace-cast, the poorly developed characters are its undoing. Without much meaningful character development, the lines between heroes and villains blur. While the film majorly focuses on Butler and Pablo Schreiber who deliver compelling performances, the others too have their moments of onscreen glory.Though the story lacks in originality, it displays more brawn than brains and excels in its production values. The production designs, cinematography, editing and background-score are all of ace quality.last_img read more

Abhishek trains gun on saffron party for dividing people

first_imgKolkata: Trinamool Youth Congress president Abhishek Banerjee lashed out at BJP once again on Wednesday, for destroying the social fabric of the country by dividing people on religious lines.While taking part in a road show in Bankura, Banerjee on Wednesday gave a clarion call to oust the saffron party from the Centre. He also urged the people to help Trinamool Congress win in all the 42 Lok Sabha constituencies in the state. Banerjee participated in the road show in favour of Trinamool Congress candidates Subrata Mukherjee and Shyamal Santra. Mukherjee is contesting the elections from the Bankura Lok Sabha seat, while Santra is fighting his electoral battle from Bishnupur. Both the candidates submitted their nominations on Wednesday. Also Read – Rs 13,000 crore investment to provide 2 lakh jobs: Mamata”GST had horrendous consequences for a section of businessmen in the country. Various small and medium scale businessmen are the ones hit worst by the hasty implementation of GST. They were forced to shut down their businesses. Our party had urged the Centre not to implement the GST in haste, as there is no proper infrastructure ready to cope with the situation,” Banerjee said. He also said that BJP is trying to divide people on the basis of their religion, in order to gain political advantage before the polls. “They are also differentiating between the Also Read – Lightning kills 8, injures 16 in staterich and the poor. People are being divided on the basis of their caste as well,” Banerjee added. “Do not cast a single vote in favour of BJP, which is doing politics over religion. People must throw them out in a democratic way. Those who seek votes in the name of our jawans have no moral right to come to power,” he said. Braving hot and humid condition, a huge number of people gathered at Bishnupur, where the Trinamool Youth Congress chief took out the road show. Banerjee, an outgoing Trinamool Congress MP from Diamond Harbour, is contesting the ongoing Lok Sabha elections from the same seat.last_img read more

Bengal celebrates Saraswati Puja

first_imgSaraswati Puja was celebrated in West Bengal on February 10 with traditional fervour. Saraswati, the Hindu goddess of music, culture and learning, was worshiped across the state and people were seen carrying clay idols of the deity with a crescent moon on the brow, riding a swan or seated on a lotus. Tiny tots and children decked up in traditional bright-yellow attires signifying ‘Basant Panchami’ – heralding the arrival of spring. Women dressed pretty in saris and boys in kurtas and performing the ‘Anjali’ (offering of flowers with prayers). Also Read – Add new books to your shelfThis time the rituals started a day before as per the almanac. But the main pomp and celebration were stored for Sunday morning which continued till midday in schools, colleges, community clubs and households, with priests chanting mantras and devotees placing seasonal palash flowers at the deity’s feet to the ringing sounds of cymbals and conch shells. Flowers, fruits and sweets placed as ‘prasad’ (offerings). Families throughout cities, towns and villages shared it among themselves. To receive the goddess’s blessings, students also placed their books, pens and musical instruments beside the idol for the entire day. Also Read – Over 2 hours screen time daily will make your kids impulsiveIt was a day of mirth for children, for whom Saraswati puja is a “no study” day. Too happy to give their textbooks a miss, they participated in cultural functions organised in localities, educational institutes and households. Small marquees came up in almost all localities where neighbours gathered to pay obeisance to the goddess, followed by sumptuous lunch comprising “khichuri” accompanied by eggplant fries, mixed vegetables and dollops of chutney and sweets. Such feasts were held in educational institutions also. “Heartiest greetings to all my brothers and sisters on the occasion of Saraswati Puja,” Chief Minister Mamata Banerjee tweeted on the occasion.last_img read more